negative effects of medical marijuanas essay

March 1, 2024

Is Marijuana Bad for Health? Here’s What We Know So Far

Marijuana’s health impacts—good and bad—are coming into focus

By Jesse Greenspan

Cappi Thompson/Getty Images

With decades of legal and social opprobrium fading fast, marijuana has become an extremely popular commercial product with more than 48 million users across the U.S. Health concerns, once exaggerated, now often seem to be downplayed or overlooked. For example, pregnant patients “often tell me they had no idea there's any risk,” says University of Utah obstetrician Torri Metz, lead author of a recent paper in the Journal of the American Medical Association on cannabis and adverse pregnancy outcomes.

Fortunately, legal reforms are also gradually making it easier to study marijuana's health effects by giving U.S. scientists more access to the drug and a wider population of users to study. Although much research remains in “early stages,” the number of studies has finally been increasing, says Tiffany Sanchez, an environmental health scientist at Columbia University. As new results accumulate, they offer a long-overdue update on what science really knows about the drug.

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In addition to minor side effects that many users joke about—such as short-term memory loss—recent studies have linked marijuana to adverse health outcomes involving the lungs, heart, brain and gonads. For example, heavy marijuana consumption seems to increase the risk of clogged arteries and heart failure , and it may impact male fertility . Smoking weed likewise can lead to chronic bronchitis and other respiratory ailments (although, unlike tobacco, it hasn't been definitively tied to lung cancer). And cannabis plants hyperaccumulate metal pollutants, such as lead, which Sanchez found can enter users' bloodstreams .

Developing adolescent brains, particularly those predisposed to mental illness, may be most at risk from overconsumption. Although psychiatric effects are hotly debated , studies suggest that heavy weed use exacerbates—or may trigger— schizophrenia , psychosis and depression in youths and that it affects behavior and academic performance. “From a safety viewpoint, young people should definitely stay away from it,” says University of Ottawa psychiatrist Marco Solmi, lead author of a recent review of cannabis and health in the British Medical Journal .

24 states have legalized recreational marijuana, with 38 allowing medical use

Moreover, the drug can cross over to fetuses during pregnancy. Several studies have linked it to low birth weights , and researchers suspect it raises the likelihood of neonatal intensive care unit admissions and stillbirths . Some cannabis dispensaries have advertised their products as a cure for morning sickness, but Metz emphasizes that safer alternatives exist.

Of course, many adults use marijuana responsibly for pleasure and relaxation. Unlike with, say, opioids, there's effectively zero risk of life-threatening overdose. Plus, “people get addicted with tobacco way faster,” says Columbia University epidemiologist Silvia Martins, who studies substance use and related laws.

Cannabis, and its derivatives, also may help alleviate pain—although some researchers contend that it performs little better than a placebo . It may also decrease chemotherapy-induced nausea, calm epileptic seizures , ease the symptoms of multiple sclerosis and serve as a sleep aid .

Recent studies have hinted that the drug might slightly reduce opioid dependency rates, although this, too, is disputed . There's some evidence that weed users tend to be more empathetic , and researchers found that elderly mice get a mental boost from the drug. Still, experts caution against self-medicating: “You should ask your doctor,” Solmi says.

Some of the recent research into marijuana is more lighthearted. One study, for instance, found that, just like people, nematode worms dosed with cannabis get the munchies .

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The Evidence—and Lack Thereof—About Cannabis

Research is still needed on cannabis’s risks and benefits. 

Lindsay Smith Rogers

Although the use and possession of cannabis is illegal under federal law, medicinal and recreational cannabis use has become increasingly widespread.

Thirty-eight states and Washington, D.C., have legalized medical cannabis, while 23 states and D.C. have legalized recreational use. Cannabis legalization has benefits, such as removing the product from the illegal market so it can be taxed and regulated, but science is still trying to catch up as social norms evolve and different products become available. 

In this Q&A, adapted from the August 25 episode of Public Health On Call , Lindsay Smith Rogers talks with Johannes Thrul, PhD, MS , associate professor of Mental Health , about cannabis as medicine, potential risks involved with its use, and what research is showing about its safety and efficacy. 

Do you think medicinal cannabis paved the way for legalization of recreational use?

The momentum has been clear for a few years now. California was the first to legalize it for medical reasons [in 1996]. Washington and Colorado were the first states to legalize recreational use back in 2012. You see one state after another changing their laws, and over time, you see a change in social norms. It's clear from the national surveys that people are becoming more and more in favor of cannabis legalization. That started with medical use, and has now continued into recreational use.

But there is a murky differentiation between medical and recreational cannabis. I think a lot of people are using cannabis to self-medicate. It's not like a medication you get prescribed for a very narrow symptom or a specific disease. Anyone with a medical cannabis prescription, or who meets the age limit for recreational cannabis, can purchase it. Then what they use it for is really all over the place—maybe because it makes them feel good, or because it helps them deal with certain symptoms, diseases, and disorders.

Does cannabis have viable medicinal uses?

The evidence is mixed at this point. There hasn’t been a lot of funding going into testing cannabis in a rigorous way. There is more evidence for certain indications than for others, like CBD for seizures—one of the first indications that cannabis was approved for. And THC has been used effectively for things like nausea and appetite for people with cancer.

There are other indications where the evidence is a lot more mixed. For example, pain—one of the main reasons that people report for using cannabis. When we talk to patients, they say cannabis improved their quality of life. In the big studies that have been done so far, there are some indications from animal models that cannabis might help [with pain]. When we look at human studies, it's very much a mixed bag. 

And, when we say cannabis, in a way it's a misnomer because cannabis is so many things. We have different cannabinoids and different concentrations of different cannabinoids. The main cannabinoids that are being studied are THC and CBD, but there are dozens of other minor cannabinoids and terpenes in cannabis products, all of varying concentrations. And then you also have a lot of different routes of administration available. You can smoke, vape, take edibles, use tinctures and topicals. When you think about the explosion of all of the different combinations of different products and different routes of administration, it tells you how complicated it gets to study this in a rigorous way. You almost need a randomized trial for every single one of those and then for every single indication.

What do we know about the risks of marijuana use?  

Cannabis use disorder is a legitimate disorder in the DSM. There are, unfortunately, a lot of people who develop a problematic use of cannabis. We know there are risks for mental health consequences. The evidence is probably the strongest that if you have a family history of psychosis or schizophrenia, using cannabis early in adolescence is not the best idea. We know cannabis can trigger psychotic symptoms and potentially longer lasting problems with psychosis and schizophrenia. 

It is hard to study, because you also don't know if people are medicating early negative symptoms of schizophrenia. They wouldn't necessarily have a diagnosis yet, but maybe cannabis helps them to deal with negative symptoms, and then they develop psychosis. There is also some evidence that there could be something going on with the impact of cannabis on the developing brain that could prime you to be at greater risk of using other substances later down the road, or finding the use of other substances more reinforcing. 

What benefits do you see to legalization?

When we look at the public health landscape and the effect of legislation, in this case legalization, one of the big benefits is taking cannabis out of the underground illegal market. Taking cannabis out of that particular space is a great idea. You're taking it out of the illegal market and giving it to legitimate businesses where there is going to be oversight and testing of products, so you know what you're getting. And these products undergo quality control and are labeled. Those labels so far are a bit variable, but at least we're getting there. If you're picking up cannabis at the street corner, you have no idea what's in it. 

And we know that drug laws in general have been used to criminalize communities of color and minorities. Legalizing cannabis [can help] reduce the overpolicing of these populations.

What big questions about cannabis would you most like to see answered?

We know there are certain, most-often-mentioned conditions that people are already using medical cannabis for: pain, insomnia, anxiety, and PTSD. We really need to improve the evidence base for those. I think clinical trials for different cannabis products for those conditions are warranted.

Another question is, now that the states are getting more tax revenue from cannabis sales, what are they doing with that money? If you look at tobacco legislation, for example, certain states have required that those funds get used for research on those particular issues. To me, that would be a very good use of the tax revenue that is now coming in. We know, for example, that there’s a lot more tax revenue now that Maryland has legalized recreational use. Maryland could really step up here and help provide some of that evidence.

Are there studies looking into the risks you mentioned?

Large national studies are done every year or every other year to collect data, so we already have a pretty good sense of the prevalence of cannabis use disorder. Obviously, we'll keep tracking that to see if those numbers increase, for example, in states that are legalizing. But, you wouldn't necessarily expect to see an uptick in cannabis use disorder a month after legalization. The evidence from states that have legalized it has not demonstrated that we might all of a sudden see an increase in psychosis or in cannabis use disorder. This happens slowly over time with a change in social norms and availability, and potentially also with a change in marketing. And, with increasing use of an addictive substance, you will see over time a potential increase in problematic use and then also an increase in use disorder.

If you're interested in seeing if cannabis is right for you, is this something you can talk to your doctor about?

I think your mileage may vary there with how much your doctor is comfortable and knows about it. It's still relatively fringe. That will very much depend on who you talk to. But I think as providers and professionals, everybody needs to learn more about this, because patients are going to ask no matter what.

Lindsay Smith Rogers, MA, is the producer of the Public Health On Call podcast , an editor for Expert Insights , and the director of content strategy for the Johns Hopkins Bloomberg School of Public Health.

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THREE ESSAYS ON THE EFFECT OF LEGALIZING MARIJUANA ON HEALTH, EDUCATION, AND SOCIAL SECURITY

The legalization of marijuana has emerged as a critical public policy issue, with far-reaching implications for health, education, and government programs at both the state and federal levels. The three essays of this dissertation show that medical marijuana legalization (MML) has a negative effect in each of these areas. The first essay shows, that the enactment of MMLs can exacerbate the crisis of overdose deaths in the United States. The study analyzes three key areas: the rate of overdose deaths caused by both legal and illegal drugs, the impact of MML on social norms regarding the perceived harm of marijuana, and an investigation into the gateway theory by examining the use of other addictive drugs. I find that MMLs increase deaths attributed to overdose by 21.5% population. MMLs s also indicate increase the number of deaths due to prescribed opioids by 44.6%, and deaths from all opioids (heroin and cocaine in addition to prescribed opioids) by 37.2 % Results suggest an overall increase in the use of marijuana, primarily due to lower perceived risk among adolescents. Additionally, results show an increase in hospital admissions due to substance abuse. The analysis suggests that legalizing medical marijuana may exaggerate the current problem of drug overdose in the United States. The second essay examines the impact of improved access to medical marijuana, measured by the proximity of schools to the nearest dispensary, on the academic performance of high school students in California. Students in schools farther from a marijuana dispensary have higher academic performance as measured through AP, ACT, SAT scores, and average GPA, and lower number of suspensions due to violence and illicit drug use. To show this, I construct the first geocoded dataset on marijuana dispensary and high school locations, use newly developed difference-in-differences estimators that rule out any bias due to heterogeneous treatment effects over time, and explore dynamic responses. This essay reveals the importance of ensuring a largest possible distance between schools and dispensaries to protect adolescents from the potential harm caused by medical marijuana. Finally, the third essay shows that in the long term, MMLs increase the number of disabled workers who receive Social Security Disability Income (SSDI) because of mental health issues. SSDI is a major social insurance program that provides benefits to workers who become disabled, and understanding how policy changes in other areas may impact this program is important. In this study, there were important differences between the results of a two-way fixed effects model and a new model by Callaway and Santa’Anna. MMLs, in theory, could either increase or decrease the number of SSDI recipients, and traditional fixed effects models suggest both could be at play; however, only the negative effect is robust to correction for heterogeneous effects. This highlights the need for future research to understand the true impact of medical marijuana legalization

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News Release

Wednesday, June 4, 2014

NIDA review summarizes research on marijuana’s negative health effects

Comprehensive review published in NEJM also discusses why risks are greatest for teen users.

The current state of science on the adverse health effects of marijuana use links the drug to several significant adverse effects including addiction, a review reports. The article, published today in the New England Journal of Medicine, is authored by scientists from the National Institute on Drug Abuse (NIDA), part of the National Institutes of Health.

“It is important to alert the public that using marijuana in the teen years brings health, social, and academic risk.”

— Dr. Nora D. Volkow Director, National Institute on Drug Abuse (NIDA)

The review describes the science establishing that marijuana can be addictive and that this risk for addiction increases for daily or young users. It also offers insights into research on the gateway theory indicating that marijuana use, similar to nicotine and alcohol use, may be associated with an increased vulnerability to other drugs.

The authors review literature showing that marijuana impairs driving, increasing the risk of being involved in a car accident and that these risks are further enhanced when combining marijuana with alcohol. The authors also discuss the implications of rising marijuana potencies and note that, because older studies are based on the effects of lower-potency (less THC) marijuana, stronger adverse health effects may occur with today’s more potent marijuana. (THC is the psychoactive or mind-altering chemical delta-9-tetrahydrocannabinol found in marijuana.)

The reviewers consider areas in which little research has been conducted. This includes possible health consequences of secondhand marijuana smoke; the long-term impact of prenatal marijuana exposure; the therapeutic potential of the individual chemicals found in the marijuana plant; and effects of marijuana legalization policies on public health.

The scientists focus on marijuana’s harmful effects on teens, an age group in which the brain rapidly develops, which is one factor that could help explain increased risks from marijuana use in this population. Research suggests that marijuana impairs critical thinking and memory functions during use and that these deficits persist for days after using. In addition, a long-term study showed that regular marijuana use in the early teen years lowers IQ into adulthood, even if users stopped smoking marijuana as adults.

The NIDA-supported 2013 Monitoring the Future Survey says that 6.5 percent of 12th graders report daily or near-daily marijuana use, with 60 percent not perceiving that regular marijuana use can be harmful. “It is important to alert the public that using marijuana in the teen years brings health, social, and academic risk,” said lead author and NIDA Director Dr. Nora D. Volkow. “Physicians in particular can play a role in conveying to families that early marijuana use can interfere with crucial social and developmental milestones and can impair cognitive development.”

This review emphasizes that marijuana use is likely to increase as state and local policies move toward legalizing marijuana for medical or recreational purposes. As use increases, so might the number of people likely to suffer negative health consequences, the review says.

For more information on marijuana and its health consequences, go to: http://www.drugabuse.gov/publications/drugfacts/marijuana .

The National Institute on Drug Abuse is a component of the National Institutes of Health, U.S. Department of Health and Human Services. NIDA supports most of the world’s research on the health aspects of drug abuse and addiction. The Institute carries out a large variety of programs to inform policy and improve practice. Fact sheets on the health effects of drugs of abuse and information on NIDA research and other activities can be found on the NIDA home page at http://www.drugabuse.gov , which is now compatible with your smartphone, iPad or tablet. To order publications in English or Spanish, call NIDA’s Drug Pubs research dissemination center at 1-877-NIDA-NIH or 240-645-0228 (TDD) or fax or email requests to 240-645-0227 or [email protected] . Online ordering is available at http://drugpubs.drugabuse.gov . NIDA’s media guide can be found at http://drugabuse.gov/mediaguide , and its new easy-to-read website can be found at http://www.easyread.drugabuse.gov .

About the National Institutes of Health (NIH): NIH, the nation's medical research agency, includes 27 Institutes and Centers and is a component of the U.S. Department of Health and Human Services. NIH is the primary federal agency conducting and supporting basic, clinical, and translational medical research, and is investigating the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, visit www.nih.gov .

NIH…Turning Discovery Into Health ®

Adverse Health Effects of Marijuana Use, by Nora D. Volkow, M.D., Ruben D. Baler, Ph.D., Wilson M. Compton, M.D., and Susan R.B. Weiss, Ph.D., published online June 4, 2014 in The New England Journal of Medicine.

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The benefits and harms of marijuana, explained by the most thorough research review yet

A new report looks at more than 10,000 studies on marijuana. It has good and bad news for pot users.

by German Lopez

Marijuana has been with humans in some way or another for thousands of years. But after all this time, there is still a lot of public debate about what, exactly, pot’s risks and benefits are.

A recent review of the research from the National Academies of Sciences, Engineering, and Medicine attempts to fill the gap in our knowledge. By combing through more than 10,000 studies published since 1999, the review, conducted by more than a dozen experts, provides the clearest look at the scientific evidence on marijuana yet.

The research finds both some strong benefits and major downsides to cannabis. It seems to be promising for chronic pain, multiple sclerosis, and cancer patients. But it also seems to pose a significant risk for respiratory problems if smoked, schizophrenia and psychosis, car crashes, lagging social achievement in life, and perhaps pregnancy-related problems.

• How Obama quietly reshaped America’s war on drugs

The findings aren’t just for marijuana; they’re for marijuana or cannabinoids, chemical compounds commonly found in pot. It’s possible that, down the line, some of the benefits in particular will be split from the marijuana leaf itself — although many drug experts believe that there’s an “entourage effect” with marijuana in which all of its cannabinoids and chemicals, which number in the hundreds , work together to make its effects as potent as possible.

One major caveat to this: The report is, by its own admission, only a best guess for a lot of its findings, because much of the research out there just isn’t very good. The report pins the lack of good research largely on government policies — particularly regulatory barriers linked to marijuana’s federal classification as a highly restricted Schedule 1 substance — that make it hard to conduct good studies on the drug. The National Academies ultimately calls for these barriers to be cut down and more research to be funded so we can get a better idea of what pot is capable of, especially as more states legalize it for both medical and recreational uses.

Still, the report is the best look at marijuana yet. It is nearly 400 pages; if you want a really deep dive into the benefits and harms of marijuana, you should read it in full . But here I’ve provided a summary of what the researchers found.

What are marijuana’s benefits?

Since the mid-1990s, 28 states have legalized marijuana for medical uses. But in all that time, the benefits of pot have remained hazy. Despite some research showing that it can be good for pain and muscle stiffness, many of the claims about what pot can do for other ailments — such as epilepsy and irritable bowel syndrome — are based on anecdotal evidence and have yet to be scientifically proven.

The report can’t fully validate or invalidate all of the claims about marijuana’s medical benefits, given that there are still no studies on some of these questions, and many of the studies that are out there are bad or lacking. But it does have some solid findings.

For one, the review confirms what previous studies have found: There is “substantial evidence” that marijuana is good for treating chronic pain. This is one of the most common reasons cited for marijuana’s medical use — particularly in light of the opioid painkiller epidemic , which has spawned in part as patients turn to opioids to try to treat debilitating pain. The report concludes that marijuana can treat chronic pain. And that may allow it to substitute more dangerous, deadlier opioid painkillers.

The report also found “conclusive evidence” that marijuana is effective for treating chemotherapy-induced nausea and vomiting. Coupled with the findings on pain, this suggests that marijuana really is a potent treatment for cancer patients in particular, who can suffer from debilitating pain and severe nausea as a result of their illness.

• One way to fight the opioid epidemic? Medical marijuana.

And the report found “substantial evidence” that marijuana can improve patient-reported multiple sclerosis spasticity symptoms. But it only found “limited evidence” for marijuana improving doctor-reported symptoms of this kind.

Beyond the strongest findings, the report found “moderate evidence” that marijuana is effective for “improving short-term sleep outcomes in individuals with sleep disturbance associated with obstructive sleep apnea syndrome, fibromyalgia, chronic pain, and multiple sclerosis.” It also found “limited evidence” for marijuana’s ability to treat appetite and weight loss associated with HIV/AIDS, improving Tourette syndrome symptoms, improving anxiety symptoms in individuals with social anxiety disorders, and improving PTSD. And there’s “limited evidence” of a correlation between marijuana and better outcomes after a traumatic brain injury.

The report also disproved — or at least cast a lot of doubt — on some of the claimed benefits of pot. It found “limited evidence” that marijuana is ineffective for treating symptoms associated with dementia and glaucoma, as well as depressive symptoms in individuals with chronic pain or multiple sclerosis.

And it found “no or insufficient evidence” for marijuana as a treatment for cancers, cancer-associated anorexia, irritable bowel syndrome, epilepsy, spasticity in patients with paralysis due to spinal cord injury, amyotrophic lateral sclerosis, Huntington’s disease, Parkinson’s disease, dystonia, drug addiction, and schizophrenia. This doesn’t mean that marijuana can’t treat any of these — some patients, who are prescribed pot for these ailments today, will swear that marijuana helped treat their epilepsy, for example — but that there’s just not enough evidence so far to evaluate the claims.

Overall, the report suggests that, as far as therapeutic benefits go, marijuana is a solid treatment for multiple symptoms associated to chronic pain, chemotherapy-induced nausea and vomiting, and multiple sclerosis. Everything else, from epilepsy to HIV/AIDS, needs more research before pot is more definitively shown to be effective or ineffective.

What are marijuana’s harms?

Marijuana is often described as one of the safest drugs out there, in part because it’s never been definitively linked to an overdose death and it’s broadly safer than other drugs like alcohol, tobacco, cocaine, and heroin. And while the National Academies’ report doesn’t find evidence of a marijuana overdose death, it does add a few wrinkles to the narrative of marijuana as a safe drug.

For one, the report finds “substantial evidence” of marijuana’s negative effects for a few conditions. For long-term marijuana smokers, there’s a risk of worse respiratory symptoms and more frequent chronic bronchitis episodes. For pregnant women who smoke pot, there’s a risk of lower birth weight for the baby. For marijuana users in general, there’s a greater risk of developing schizophrenia and other psychoses. And there’s a link between marijuana use and increased risk of car crashes.

The report also found “limited evidence” of links between marijuana use and several other negative outcomes, including an increased risk of testicular cancer, triggering a heart attack, chronic obstructive pulmonary disease, and pregnancy complications. And it found “moderate” to “limited” evidence that marijuana use might worsen symptoms or risk for some mental health issues, including depressive disorders, bipolar disorder, suicidal ideation and suicide attempts among heavier users, and anxiety disorders, particularly social anxiety disorder among regular users.

Besides medical conditions, the report found evidence for some psychosocial problems. There’s “moderate evidence” that acute marijuana use impairs learning, memory, and attention. There’s “limited evidence” of marijuana use and worse outcomes in education, employment, income, and social functioning.

• America can end its war on drugs. Here's how.

There was some good news: The report found “moderate evidence” of no link between marijuana smoking and lung cancer or marijuana use and head and neck cancers, which are commonly linked to tobacco. There was also “moderate evidence” of better cognitive performance among individuals with psychotic disorders and a history of marijuana use.

The report, however, couldn’t find sufficient evidence for pot’s links to a lot of problems: other types of cancer, an increased chronic risk of heart attack, asthma, later outcomes for infants born of mothers that used marijuana during pregnancy, deadly pot overdoses, and PTSD.

With the problems specifically linked to smoking marijuana, it’s worth noting that other forms of consumption — vaping and edibles in particular — may not carry the same risk. More research will be needed to evaluate that, particularly for vaping.

The report also found some “substantial evidence” that more pot use can lead to problematic marijuana use — what one typically thinks of as excessive use or even dependence. It also outlined, with “limited” to “substantial” evidence, some of the risk factors for problematic marijuana use, including being male, smoking cigarettes, a major depressive order, exposure to combined use of other drugs, and use at an earlier age. But it also cited “limited” to “moderate” evidence to rule out a few risk factors, including anxiety, personality, and bipolar disorders, adolescent ADHD, and alcohol or nicotine dependence.

It also found a “limited” to “moderate” evidence of a correlation between marijuana use and use of other illicit drugs. This is the typical evidence cited for the so-called “gateway” effect: that marijuana use may lead to the use of harder drugs.

One caveat to much of the research: correlation is not always causation. For example, in the case of the “gateway” effect, other researchers argue that the correlation between pot and harder drug use may just indicate that people prone to all sorts of drug use only start with marijuana because it’s the cheapest and most accessible of the illicit drugs. If cocaine or heroin were cheaper and more accessible, there’s a good chance people would start with those drugs first.

Still, the bottom line is that marijuana does pose some harms — particularly for people at risk of developing mental health disorders, pregnant women, those vulnerable to respiratory problems, and anyone getting into a car. And while some of these harms may be overcome by marijuana’s benefits or curtailed by consuming pot without smoking it, the evidence shows that weed’s reputation as a safe drug is undeserved.

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Essays on the Effects of Medical Marijuana Laws

• Smart, Rosanna
• Advisor(s): Lleras-Muney, Adriana

Over half of the US states have adopted "medical marijuana" laws (MMLs), and 58% of Americans now favor marijuana legalization. Despite public support, federal law continues to prohibit the use and sale of marijuana due to public health concerns of increased dependence and abuse, youth access, and drugged driving. These essays contribute toward understanding the likely health consequences of marijuana liberalization using evidence from MMLs.

Chapter 1 -- Growing Like Weed: Explaining Variation in Medical Marijuana Market Size provides a comprehensive analysis of the determinants of growth in legal medical marijuana markets. Newly collected data on medical marijuana patient registration rates shows that there is substantial heterogeneity in medical marijuana participation over time and across states. This variation is primarily driven by the combined effects of federal enforcement policy and state supply restrictions on legal production costs. Chapter 2 -- The Kids Aren't Alright: Effects of Medical Marijuana Market Growth on Marijuana Use then studies the effect of growth in legal medical marijuana markets on recreational use. Findings show that expansion of legal medical marijuana market size significantly increases the prevalence of recreational cannabis use by both adults and adolescents. Reaching the median state's legal market size would increase the prevalence of marijuana use in the past month by 6% for adolescents aged 12-17, by 9% for 18-25 year-olds, and by 18% for adults over age 25.

The welfare implications of these changes largely depend on the externalities and internalities associated with marijuana use. To study this, Chapter 3 -- On the Health Consequences of Increased Medical Marijuana Access examines the effects of increased marijuana availability on traffic fatalities and mortality related to opioid and alcohol poisonings. In the aggregate, greater medical marijuana access decreases mortality from these causes. However, the aggregate effect masks an important welfare trade-off generated by age differences in the elasticity of substitution between marijuana and alcohol. For adults aged 45-64, greater marijuana availability reduces mortality related to alcohol and opioid poisonings by 7-11% and 12-16% respectively. In contrast, for youths aged 15-20, marijuana access generates negative externalities in the form of a 6% increase in traffic fatalities, with large and significant effects on alcohol- and cannabis-related accidents.

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Cannabis Health Effects

• Cannabis use may have a wide range of health effects on the body and brain.
• There are several risk factors and negative health outcomes associated with cannabis use.

How cannabis can affect your health

Cannabis is the most commonly used federally illegal drug in the United States, with an estimated 61.9 million people using it in 2022. 1 Cannabis use may have a wide range of health effects on the body and brain. 2 Click on the sections below to learn more about how cannabis use can affect your health.

Cannabis health effects

There are health risks associated with using cannabis regardless of how it is used. These include:

Cannabis Use Disorder

People who use cannabis can struggle with physical dependency and controlling their use. This is concerning as there is evidence suggesting the use of highly concentrated THC products is associated with more severe cannabis use disorder symptoms. 3 While approximately 3 in 10 persons who report cannabis have a cannabis use disorder, this figure is rising. 1 4 Some signs and symptoms of cannabis use disorder include trying but failing to quit using cannabis or giving up important activities with friends and family in favor of using cannabis. 5 The risk of developing cannabis use disorder is stronger in people who start using cannabis during youth or adolescence and who use cannabis more frequently. 6

Brain Health

Cannabis use directly affects brain function—specifically the parts of the brain responsible for memory, learning, attention, decision making, coordination, emotions, and reaction time. 7 8

Heart Health

Cannabis can make the heart beat faster and raise blood pressure immediately after use. 9 10 It could also lead to increased risk of stroke, heart disease, and other vascular diseases. 11 12 13 14 15

Cannabis, like alcohol, negatively affects several skills required for safe driving. You can choose not to drive—and remind your friends and family to do the same—after using cannabis.

• It can slow reaction time and ability to make decisions. 7 16
• Cannabis can impair coordination and distort perception. 7 16
• The use of multiple substances (such as cannabis and alcohol) at the same time can increase impairment. 17
• Some studies have shown an association between cannabis use and car crashes; however, more research is needed. 7 17

Lung Health

Smoked cannabis, regardless of how it is smoked, can harm lung tissues and cause scarring and damage to small blood vessels. 18 19

Mental Health

Cannabis use has been linked to social anxiety, depression, and schizophrenia (a type of mental illness where people might see or hear things that aren't really there), but scientists don't yet fully understand the relationships between these mental health disorders and cannabis use. 20 21

Unintentional Poisoning

Edibles, or food and drink products infused with cannabis, have some different risks than smoked cannabis, including a greater risk of poisoning. 7 Some cannabis edibles have packaging designed to mimic the appearance of well-known branded snacks and candy that appeal to children, which increases the risk for unintentional ingestion. Children who consume THC-containing products can become very sick. 22

If You Use Cannabis Products‎

If you use cannabis products, keep them in a locked childproof container and out of the sight and reach of children. For additional questions, you can contact your healthcare provider, your health department, your local or regional poison control center at 1-800-222-1222 , or 911 if it's an emergency.

FDA Warns About Children Accidentally Ingesting Food Products Containing THC

• Substance Abuse and Mental Health Services Administration. Key substance use and mental health indicators in the United States: Results from the 2022 National Survey on Drug Use and Health (HHS Publication No. PEP23-07-01-006, NSDUH Series H-58). Center for Behavioral Health Statistics and Quality, Substance Abuse and Mental Health Services Administration. 2023. https://www.samhsa.gov/data/sites/default/files/reports/rpt42731/2022-nsduh-nnr.pdf . Accessed on February 9, 2024.
• Rosenberg EC, Tsien RW, Whalley BJ, et al. Cannabinoids and Epilepsy. Neurotherapeutics . 2015;12(4):747-768. doi: 10.1007/s13311-015-0375-5.
• Freeman TP, Winstock AR. Examining the profile of high-potency cannabis and its association with severity of cannabis dependence. Psychol Med. 2015;45(15):3181-3189. doi: 10.1017/S0033291715001178
• Substance Abuse and Mental Health Services Administration. Key substance use and mental health indicators in the United States: Results from the 2021 National Survey on Drug Use and Health (HHS Publication No. PEP22-07-01-005, NSDUH Series H-57). Center for Behavioral Health Statistics and Quality, Substance Abuse and Mental Health Services Administration. https://www.samhsa.gov/data/report/2021-nsduh-annual-national-report . Accessed on February 9, 2024.
• American Psychiatric Association, Diagnostic and Statistical Manual of Mental Disorders. 5th ed. Arlington, VA, 2013.
• Winters KC, Lee C-YS. Likelihood of developing an alcohol and cannabis use disorder during youth: Association with recent use and age. Drug Alcohol Depend . 2008;92(1-3):239-247. doi: 10.1016/j.drugalcdep.2007.08.005.
• National Academies of Sciences, Engineering, and Medicine. The health effects of cannabis and cannabinoids: the current state of evidence and recommendations for research. Washington, DC: The National Academies Press; 2017. https://nap.nationalacademies.org/catalog/24625/the-health-effects-of-cannabis-and-cannabinoids-the-current-state . Accessed February 8, 2024.
• Batalla A, Bhattacharyya S, Yücel M, et al. Structural and functional imaging studies in chronic cannabis users: A systematic review of adolescent and adult findings. PLoS One . 2013;8(2):e55821. doi: 10.1371/journal.pone.0055821.
• Sidney S. Cardiovascular consequences of marijuana use. J Clin Pharmacol . 2002;42(S1):64S-70S. https://doi.org/10.1002/j.1552-4604.2002.tb06005.x
• Subramaniam VN, Menezes AR, DeSchutter A, et al. The cardiovascular effects of marijuana: Are the potential adverse effects worth the high? Mo Med . 2019;116(2):146-153.
• Wolff V, Armspach JP, Lauer V, et al. Cannabis-related stroke: Myth or reality? Stroke . 2013;44(2):558-563. doi: 10.1161/STROKEAHA.112.671347.
• Wolff V, Zinchenko I, Quenardelle V, et al. Characteristics and prognosis of ischemic stroke in young cannabis users compared with non-cannabis users. J Am Coll Cardiol . 2015;66(18):2052-2053. doi: 10.1016/j.jacc.2015.08.867.
• Franz CA, Frishman WH. Marijuana use and cardiovascular disease. Cardiol Rev . 2016;24(4):158-162. doi: 10.1097/CRD.0000000000000103.
• Rumalla K, Reddy AY, Mittal MK. Association of recreational marijuana use with aneurysmal subarachnoid hemorrhage. J Stroke Cerebrovasc Dis . 2016;25(2):452-460. doi: 10.1016/j.jstrokecerebrovasdis.2015.10.019.
• Rumalla K, Reddy AY, Mittal MK. Recreational marijuana use and acute ischemic stroke: A population-based analysis of hospitalized patients in the United States. J Neurol Sci . 2016;364:191-196. doi: 10.1016/j.jns.2016.01.066.
• Compton R. Marijuana-impaired driving. A report to Congress. Washington, DC: National Highway Traffics Safety Administration, 2017. https://www.nhtsa.gov/sites/nhtsa.dot.gov/files/documents/812440-marijuana-impaired-driving-report-tocongress.pdf . Accessed February 9, 2024.
• Lacey JH, Kelley-Baker T, Berning A, et al. Drug and alcohol crash risk: A case-control study (Report No. DOT HS 812 355). Washington, DC: National Highway Traffic Safety Administration; 2016.
• Tashkin DP, Simmons MS, Tseng CH. Impact of changes in regular use of marijuana and/or tobacco on chronic bronchitis. COPD . 2012;9(4):367-374. doi: 10.3109/15412555.2012.671868.
• Wang X, Derakhshandeh R, Liu J, et al. One minute of marijuana secondhand smoke exposure substantially impairs vascular endothelial function. J Am Heart Assoc . 2016;5(8):e003858. doi: 10.1161/JAHA.116.003858.
• Fattore L, Fratta W. How important are sex differences in cannabinoid action? Br J Pharmacol . 2010;160(3):544-548. doi: 10.1111/j.1476-5381.2010.00776.x.
• Volkow ND, Swanson JM, Evins AE, et al. Effects of cannabis use on human behavior, including cognition, motivation, and psychosis: A review. JAMA Psychiatry . 2016;73(3):292-297. doi: 10.1001/jamapsychiatry.2015.3278.
• Richards JR, Smith NE, Moulin AK. Unintentional cannabis ingestion in children: A systematic review. J Pediatr . 2017;190:142-152. doi: 10.1016/j.jpeds.2017.07.005.

Cannabis and Public Health

Cannabis—which can also be called marijuana —is the most commonly used federally illegal drug in the United States.

How does marijuana affect the brain? Psychological researchers examine impact on different age groups over time

New legislation is helping scientists and manufacturers study the effects of cannabis and develop guidelines for use

Vol. 54 No. 4 Print version: page 20

• Cognition and the Brain
• Substance Use, Abuse, and Addiction
• Neuropsychology

In 2021, more than 36 million people 12 and older reported using cannabis in the past month—double the number compared with a decade earlier, according to data from the Substance Abuse and Mental Health Services Administration’s National Survey of Drug Use and Health . Cannabis users have access to an unprecedented variety of purported antidotes for everything from anxiety to insomnia to posttraumatic stress disorder (PTSD)—claims that have yet to be validated by research. Among the popular offerings are cannabis concentrates with extremely high levels of tetrahydrocannabinol (THC), the main psychoactive compound in cannabis that produces the euphoric “high” sensation.

“Science is having a hard time keeping up with the enormous increase in products available, especially because researchers have been hamstrung by regulatory hurdles,” said Columbia University’s Margaret Haney, PhD, a professor of neurobiology and director of the school’s Cannabis Research Laboratory. Those hurdles include marijuana’s classification as a Schedule I substance, which requires researchers to earn approval from multiple federal agencies for studies.

APA has been advocating for reforms in cannabis research regulations to ensure that science is available to inform product policies, clinical decisions for therapeutic use, and public understanding about the health effects across the life span. In December 2022, President Joe Biden signed into law the Medical Marijuana and Cannabidiol Research Expansion Act—legislation that will make it easier for scientists and manufacturers to study the effects of marijuana and develop guidelines for use. For decades, the University of Mississippi was the only federally approved cultivator of cannabis for scientists, but the new law will allow other entities to manufacture and distribute the drug for research.

Although the legislation does not allow scientists to buy and study products available in dispensaries, psychologists hope that the new policy is a harbinger of increasing federal support for gathering more science-based data to educate the public and health care providers. The latest findings are shedding light on how biological brain differences may influence cognitive effects in adolescent users, how cannabis can interfere with pharmaceutical medications for depression and other mental health issues, and the potential mental benefits for older adults. “For many years, cannabis was demonized, but now we’ve swung to the other extreme because it’s advertised as the cure for everything,” said Haney. “We need data to inform honest discussions about the risk of drug abuse, the therapeutic potential, and the impact on different age groups over time.”

The adolescent user

One of the top priorities among cannabis researchers is clarifying how the drug—which has been legalized for recreational use in 21 states and for medical use in 37 states—affects the developing brain. “I’m concerned by the increase in the number of people who are using cannabis at higher doses on a daily basis,” said Nora Volkow, MD, director of the National Institute on Drug Abuse (NIDA). “Adolescents are more vulnerable to addiction, and once they are using compulsively, cannabis can interfere with memory and learning.” In one study, 15% of people of all ages who used cannabis in the past 30 days met the Diagnostic and Statistical Manual of Mental Disorders (Fifth Edition) criteria for cannabis use disorder, and rates specifically among youth ages 12 to 20 were significantly higher at 23% ( Richter, L., et al., The American Journal of Drug and Alcohol Abuse , Vol. 43, No. 3, 2017 ).

To investigate the effects of cannabis use on adolescents, Joanna Jacobus, PhD, an associate professor of psychiatry at the University of California San Diego (UCSD), launched longitudinal studies that followed teenagers who had started using and compared them with nonusing controls. Adolescents who continued using for 3 years at least 2 times per week had thicker cerebral cortices, particularly in the frontal and parietal regions than controls ( Developmental Cognitive Neuroscience , Vol. 16, 2015 ). The cannabis users performed more poorly on cognitive tests, especially in attention and memory tasks, and teenagers who started using earlier in life performed more poorly than those who started using later or nonusers ( Neuropsychology , Vol. 29, No. 6, 2015 ).

More recently, Jacobus began collecting data on youth before they started using cannabis to understand if the drug caused the poorer neural health outcomes, or if there were preexisting biological brain differences that were also influencing cognitive outcomes. A 6-year study showed preexisting differences in gray matter and functional brain activation that could be contributing to poorer cognitive performance in adolescent cannabis users. “We found that there are biological brain differences that can increase the chances that an adolescent will start using cannabis, and these differences may also increase their vulnerability to negative developmental outcomes,” said Jacobus.

Jacobus is optimistic that there will be more data soon about which youth are at higher risk of initiating cannabis use as researchers follow more than 11,000 youth enrolled in the NIH’s ABCD Study, the largest long-term study of brain development and child health in the United States. The study began in 2015 when children were 9 or 10, and Jacobus and her colleagues are collecting data on 700 participants from San Diego County with tools such as MRI imaging, cognitive and genetic marker testing, and questionnaires about family environment, school activities, and more.

Like Jacobus, Jonathan Schaefer, PhD, a researcher in the psychology department at the University of Minnesota, was eager to explore the cause of emotional and cognitive problems among adolescents who used cannabis. He tapped into data collected from more than 3,000 twins who had been followed from adolescence into their early 30s. By comparing identical twins who shared genetics and a home environment, he could better separate the effects of cannabis use on negative outcomes from the effects of these background factors.

He did not find evidence that cannabis caused more mental health problems or decreased cognitive ability, but the drug was linked to lower educational attainment, occupational status, and income ( PNAS , Vol. 118, No. 14, 2021 ). In a subsequent exploratory analysis, the data revealed that in identical twins, the twins who used more cannabis than their cotwins also had lower GPAs and academic motivation. “Our findings provide evidence against the idea that cannabis has dramatic, long-lasting effects on the brain,” Schaefer said. “Instead, they raise the possibility that we should be more concerned about acute, shorter-term drug effects that have lingering consequences.” For example, students who are using cannabis regularly may have trouble focusing and feeling motivated during school, which might ultimately affect their educational and career trajectory. Schaefer cautions that even if cannabis does not cause permanent, deleterious changes in the brain, it is still risky for adolescents to use because it may negatively impact other important longer-term life outcomes, such as educational attainment, risk of developing a cannabis use disorder, and lung health. These findings were also based on twins who were using in the 1990s and early 2000s, so the results do not account for the effects of newer, high-potency products, Schaefer said.

Data collected from more than 1,000 New Zealanders over 4 decades has also given researchers a glimpse into how frequent, long-term cannabis use—often starting in the teen years—affects the aging process. The study participants were followed from birth to age 45, and the long-term users were less financially prepared for aging, with lower credit scores and less money in savings and investments. They also reported more social problems, such as loneliness, lower life satisfaction, and less social support ( The Lancet: Healthy Longevity , Vol. 3, No. 10, 2022 ).

“Social support and financial preparedness in midlife are related to better aging and longer lives,” said Madeline Meier, PhD, an associate professor of psychology at Arizona State University and author of the study. “People may not realize that if they become dependent on cannabis, there could be consequences for healthy aging and well-being.” The researchers investigated whether factors in childhood—like IQ, low self-control, or socioeconomic status—could explain the outcomes, but they did not find evidence for this in the study. Long-term cannabis users frequently developed dependence on other substances, such as alcohol and tobacco, and the polysubstance use could also be contributing to at least some of the financial and social problems in midlife, Meier said.

Mixing marijuana with mental health issues

Psychologists also share a sense of urgency to clarify how cannabis affects people who suffer from preexisting mental health conditions. Many veterans who suffer from PTSD view cannabis as a safe alternative to other drugs to alleviate their symptoms ( Wilkinson, S. T., et al., Psychiatric Quarterly , Vol. 87. No. 1, 2016 ). To investigate whether marijuana does in fact provide relief for PTSD symptoms, Jane Metrik, PhD, a professor of behavioral and social sciences at the Brown University School of Public Health and a core faculty member at the university’s Center for Alcohol and Addiction Studies, and colleagues followed more than 350 veterans for a year. They found that more frequent cannabis use worsened trauma-related intrusion symptoms—such as upsetting memories and nightmares—over time ( Psychological Medicine , Vol. 52, No. 3, 2022 ). A PTSD diagnosis was also strongly linked with cannabis use disorder a year later. “Cannabis may give temporary relief from PTSD because there is a numbing feeling, but this fades and then people want to use again,” Metrik said. “Cannabis seems to worsen PTSD and lead to greater dependence on the drug.”

Metrik, who also works as a psychologist at the Providence VA Medical Center, has also been studying the effects of using cannabis and alcohol at the same time. “We need to understand whether cannabis can act as a substitute for alcohol or if it leads to heavier drinking,” she said. “What should we tell patients who are in treatment for problem drinking but are unwilling to stop using cannabis? Is some mild cannabis use OK? What types of cannabis formulations are helpful or harmful for people who have alcohol use disorder?”

Though there are still many unanswered questions, Metrik has seen cases that suggest adding cannabis to heavy drinking behavior is risky. Sometimes people can successfully quit drinking but are unable to stop using cannabis, which can also intensify depression and lead to cannabis hyperemesis syndrome—repeated and severe bouts of vomiting that can occur in heavy cannabis users, she said. Cannabis withdrawal symptoms such as irritability, anxiety, increased cravings, aggression, and restlessness usually subside after 1 to 2 weeks of abstinence, but insomnia tends to persist longer than the other symptoms, she said.

Cannabis may also interfere with pharmaceutical medications patients are taking to treat mental health issues. Cannabidiol (CBD) can inhibit the liver enzymes that metabolize medications such as antidepressants and antipsychotics, said Ryan Vandrey, PhD, a professor of psychiatry and behavioral sciences at Johns Hopkins University and president of APA’s Division 28 (Society for Psychopharmacology and Substance Use). “This could lead to side effects because the medication is in the body longer and at higher concentrations,” he said. In a recent study, he found that a high dose of oral CBD also inhibited the metabolism of THC, so the impairment and the subjective “high” was significantly stronger and lasted for a longer time ( JAMA Network Open , Vol. 6, No. 2, 2023 ). This contradicts the common conception that high levels of CBD reduce the effects of THC, he said. “This interaction could lead to more adverse events, such as people feeling sedated, dizzy, [or] nervous, or experiencing low blood pressure for longer periods of time,” Vandrey said.

The interactions between CBD, THC, and pharmaceutical medications also depend on the dosing and the route of administration (oral, topical, or inhalation). Vandrey is advocating for more accurate labeling to inform the public about the health risks and benefits of different products. “Cannabis is the only drug approved for therapeutic use through legislative measures rather than clinical trials,” he said. “It’s really challenging for patients and medical providers to know what dose and frequency will be effective for a specific condition.”

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Health impacts of cannabis – benefits, harms and many unknowns.

A new report by Royal Society Te Apārangi summarises what is known about the potential risks and benefits to health from the use of recreational and medicinal cannabis.

It finds evidence that cannabis-based medicines have some therapeutic effect in specific clinical situations and that recreational cannabis use can have some negative health outcomes. The report finds large knowledge gaps in understanding the health effects of both recreational cannabis and cannabis-based medicines, particularly in specific groups of the population, and this lack of knowledge poses a public health risk.

Royal Society Te Apārangi President Professor Wendy Larner says the report draws heavily on the 2017 publication by the US National Academies of Sciences, Engineering and Medicine: The Health Effects of Cannabis and Cannabinoids: The Current State of Evidence and Recommendations as well as additional literature of relevance to Aotearoa.

“With changes to New Zealand’s legislation on prescribing cannabis and the upcoming referendum on whether New Zealand should legalise recreational cannabis, Royal Society Te Apārangi has prepared this report to assist people considering the opportunities and risks to health associated with cannabis use.”

Associate Professor Joe Boden, Department of Psychological Medicine, University of Otago, who was one of the report’s reviewers, says that for medicinal cannabis, there is evidence of effectiveness to treat a small number of specific conditions but the evidence is not well established as it hasn’t been widely tested in clinical trials.  “Cannabis-based medicines have been shown to have some therapeutic effects in treating chronic pain, nausea from chemotherapy, muscle spasms due to multiple sclerosis and in rare forms of epilepsy, but we don’t have good evidence that they work better than the existing medicines available to treat these conditions.”

Dr Irene Braithwaite, Medical Research Institute of New Zealand, who also was a reviewer of the report, says that cannabis-based medicines, many of which are derived from plant material, have not been through the same vigorous efficacy or safety testing as existing medicines. “The levels and types of cannabinoids in these plant-based preparations can vary greatly due to different growing, harvest and storage conditions. This makes it difficult to draw conclusions by comparing or pooling the results from the limited number of studies that do exist,” says Dr Braithwaite. 

For recreational use, some harms are also seen. “Recreational cannabis is associated with negative outcomes including mental illness, particularly in youth, drug use disorders, respiratory illness, impaired cognition, increased road accidents and lower birthweight in babies born to women exposed to cannabis,” says Professor Michelle Glass, Head of the Department of Pharmacology and Toxicology at University of Otago. “People may assume cannabis is largely safe as it has been used by people for so long, but this is not necessarily the case.”

The report finds many gaps in the research literature, particularly in population groups thought to be at most risk from cannabis use: those under 18 years, pregnant and breastfeeding women, people over 50 years and heavy cannabis users. 

An area where the risks are clear is synthetic cannabis, says Professor Glass, who studies cannabinoids in her research. 

“Calling it synthetic cannabis is misleading as it’s not cannabis. It’s non-cannabis plant material sprayed with lab-made chemicals that mimic the effect of cannabis in the body but tend to be much more powerful. In 2017 there were approximately 45 deaths linked to synthetic cannabinoids in New Zealand and every day, ambulance services in New Zealand report multiple life-threatening cases related to synthetic cannabinoid use. 

“Being so different to cannabis, it can be difficult to identify with standard drug screening techniques.”

Professor Glass says it is worth noting that synthetic cannabis would remain illegal, regardless of the outcome of the public referendum, such is its great potential to cause harm. 

View report Cannabis: How it affects our health 

Key facts about cannabis and cannabinoids

(see full report for more detail and references)

Q: What is cannabis?

A: Cannabis grows as separate male and female plants and produces a large number of bioactive compounds. The best known are THC (Tetrahydrocannabinol) that produces a ‘high’ when taken and CBD (cannabidiol) that doesn’t but has other effects on the body.

Q. Why does cannabis affect us?

A. Some compounds in cannabis, like THC, affect us because they interact with our own cannabinoid system. We have cannabinoid receptors in our brain and gut, in particular, and we produce cannabinoids to regulate appetite, form memories, calm fear, affect our movement and posture and regulate our immune system.

Q: How long have humans used cannabis as a medicine?

A: Written records show cannabis was used for medicinal purposes in China as far back as 6,000 years ago.

Q. What medical conditions can cannabis treat?

A. The evidence for cannabis-based medicine is not well established as it hasn’t been widely tested in clinical trials. There is evidence that cannabis-based medicines may have some effect as an additional treatment option for controlling chronic pain in adults, reducing nausea and vomiting from chemotherapy, easing pain from muscle spasms in people with multiple sclerosis and treating two rare forms of severe epilepsy in children.

Q. How do people take medicinal cannabis?

A. Medicinal cannabis is usually taken as a spray, oil, capsule or as pharmaceutical grade plant material.

Q. What cannabis-based medicines are available in New Zealand?

A. Medical cannabis preparations with low levels of the psychoactive compound, THC, can be prescribed for palliative care and the oral spray Sativex® can be prescribed for those with multiple sclerosis. Changes are underway, however, to allow doctors to prescribe medicinal cannabis more widely.

Q. What risks are associated with the way people take cannabis?

A. The safest form is pharmaceutical products such as sprays, oils or capsules. Smoking cannabis exposes users to toxic compounds created at high temperatures and it can lead to a chronic cough and phlegm production. Vaporising at lower temperatures (such as vaping) also exposes a user to toxic compounds from additives, solvents and flavouring. Edible forms can lead to excessively high doses and accidental ingestion. Synthetic cannabis poses the greatest risk because the active chemicals are much stronger than natural cannabis and can have longer lasting and more dangerous effects on the body.

Q. What is synthetic cannabis?

A. Synthetic cannabis is non-cannabis plant material sprayed with chemicals that mimic the effect of cannabis but often has a stronger effect on the body so is more risky to take. Approximately 45 deaths in New Zealand were linked to synthetic cannabis use in 2017 and ambulance services report multiple life-threatening cases related to synthetic cannabis use every day. Its use would remain illegal regardless of the outcome of the recreational cannabis referendum.

Q. How does recreational cannabis affect physical health?

A. Smoking cannabis regularly can cause a chronic cough and phlegm production. It can affect brain development and short term memory, particularly in young people, making learning more difficult. It can also lead to drug use disorders. Maternal cannabis exposure can lead to lower birthweights and negatively affect a baby’s brain and nerve development. Cannabis use can also lead to increased road accidents.

Q. How does recreational cannabis affect mental health?

A. Cannabis may have an adverse effect on mental health but more research is needed to confirm this. It may increase the risks of schizophrenia and psychosis, bipolar disorder, depression and anxiety. Also, people can develop problem cannabis use and may become addicted.

Q. Is it safe to drive after using cannabis?

A. Driving under the influence of cannabis increases the risk of having a crash. The amount of cannabis at which driving becomes unsafe is unknown and impairment from cannabis is difficult to measure.

Q. What more do we need to know about the effects of cannabis?

A. The lack of quality information on the effects of both medicinal and recreational cannabis poses a public health risk because we don’t know enough about how safe or effective it is. Urgent research is needed on population groups thought to be at most risk: those under 18, pregnant and breastfeeding women, people over 50 years and heavy cannabis users.

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Cannabis (Marijuana) DrugFacts

What is marijuana.

Marijuana refers to the dried leaves, flowers, stems, and seeds from the Cannabis sativa or Cannabis indica plant. The plant contains the mind-altering chemical THC and other similar compounds. Extracts can also be made from the cannabis plant (see " Marijuana Extracts ").

According to the National Survey on Drug Use and Health , cannabis (marijuana) is one of the most used drugs in the United States, and its use is widespread among young people. In 2021, 35.4% of young adults aged 18 to 25 (11.8 million people) reported using marijuana in the past year. 1 According to the Monitoring the Future survey , rates of past year marijuana use among middle and high school students have remained relatively steady since the late 1990s. In 2022, 30.7% of 12th graders reported using marijuana in the past year and 6.3% reported using marijuana daily. In addition, many young people also use vaping devices to consume cannabis products. In 2022, nearly 20.6% of 12th graders reported that they vaped marijuana in the past year and 2.1% reported that they did so daily. 2

Legalization of marijuana for medical use or adult recreational use in a growing number of states may affect these views. Read more about marijuana as medicine in our DrugFacts: Marijuana as Medicine .

How do people use marijuana?

People smoke marijuana in hand-rolled cigarettes (joints) or in pipes or water pipes (bongs). They also smoke it in blunts—emptied cigars that have been partly or completely refilled with marijuana. To avoid inhaling smoke, some people are using vaporizers. These devices pull the active ingredients (including THC) from the marijuana and collect their vapor in a storage unit. A person then inhales the vapor, not the smoke. Some vaporizers use a liquid marijuana extract.

People can mix marijuana in food ( edibles ), such as brownies, cookies, or candy, or brew it as a tea. A newly popular method of use is smoking or eating different forms of THC-rich resins (see " Marijuana Extracts ").

Marijuana Extracts

Smoking THC-rich resins extracted from the marijuana plant is on the rise. People call this practice dabbing . These extracts come in various forms, such as:

• hash oil or honey oil —a gooey liquid
• wax or budder —a soft solid with a texture like lip balm
• shatter —a hard, amber-colored solid

These extracts can deliver extremely large amounts of THC to the body, and their use has sent some people to the emergency room. Another danger is in preparing these extracts, which usually involves butane (lighter fluid). A number of people have caused fires and explosions and have been seriously burned from using butane to make extracts at home. 3,4

How does marijuana affect the brain?

Marijuana has both short-and long-term effects on the brain.

Short-Term Effects

When a person smokes marijuana, THC quickly passes from the lungs into the bloodstream. The blood carries the chemical to the brain and other organs throughout the body. The body absorbs THC more slowly when the person eats or drinks it. In that case, they generally feel the effects after 30 minutes to 1 hour.

THC acts on specific brain cell receptors that ordinarily react to natural THC-like chemicals. These natural chemicals play a role in normal brain development and function.

Marijuana over activates parts of the brain that contain the highest number of these receptors. This causes the "high" that people feel. Other effects include:

• altered senses (for example, seeing brighter colors)
• altered sense of time
• changes in mood
• impaired body movement
• difficulty with thinking and problem-solving
• impaired memory
• hallucinations (when taken in high doses)
• delusions (when taken in high doses)
• psychosis (risk is highest with regular use of high potency marijuana)

Long-Term Effects

Marijuana also affects brain development. When people begin using marijuana as teenagers, the drug may impair thinking, memory, and learning functions and affect how the brain builds connections between the areas necessary for these functions. Researchers are still studying how long marijuana's effects last and whether some changes may be permanent.

For example, a study from New Zealand conducted in part by researchers at Duke University showed that people who started smoking marijuana heavily in their teens and had an ongoing marijuana use disorder lost an average of 8 IQ points between ages 13 and 38. The lost mental abilities didn't fully return in those who quit marijuana as adults. Those who started smoking marijuana as adults didn't show notable IQ declines. 5

In another recent study on twins, those who used marijuana showed a significant decline in general knowledge and in verbal ability (equivalent to 4 IQ points) between the preteen years and early adulthood, but no predictable difference was found between twins when one used marijuana and the other didn't. This suggests that the IQ decline in marijuana users may be caused by something other than marijuana, such as shared familial factors (e.g., genetics, family environment). 6 NIDA’s Adolescent Brain Cognitive Development (ABCD) study, a major longitudinal study, is tracking a large sample of young Americans from late childhood to early adulthood to help clarify how and to what extent marijuana and other substances, alone and in combination, affect adolescent brain development. Read more about the ABCD study on our Longitudinal Study of Adolescent Brain and Cognitive Development (ABCD Study) webpage.

A Rise in Marijuana’s THC Levels

The amount of THC in marijuana has been increasing steadily over the past few decades. 7 For a person who's new to marijuana use, this may mean exposure to higher THC levels with a greater chance of a harmful reaction. Higher THC levels may explain the rise in emergency room visits involving marijuana use.

The popularity of edibles also increases the chance of harmful reactions. Edibles take longer to digest and produce a high. Therefore, people may consume more to feel the effects faster, leading to dangerous results.

Higher THC levels may also mean a greater risk for addiction if people are regularly exposing themselves to high doses.

What are the other health effects of marijuana?

Marijuana use may have a wide range of effects, both physical and mental.

Physical Effects

• Breathing problems. Marijuana smoke irritates the lungs, and people who smoke marijuana frequently can have the same breathing problems as those who smoke tobacco. These problems include daily cough and phlegm, more frequent lung illness, and a higher risk of lung infections. Researchers so far haven't found a higher risk for lung cancer in people who smoke marijuana. 8
• Increased heart rate. Marijuana raises heart rate for up to 3 hours after smoking. This effect may increase the chance of heart attack. Older people and those with heart problems may be at higher risk.
• Problems with child development during and after pregnancy. One study found that about 20% of pregnant women 24-years-old and younger screened positive for marijuana. However, this study also found that women were about twice as likely to screen positive for marijuana use via a drug test than they state in self-reported measures. 9 This suggests that self-reported rates of marijuana use in pregnant females is not an accurate measure of marijuana use and may be underreporting their use. Additionally, in one study of dispensaries, nonmedical personnel at marijuana dispensaries were recommending marijuana to pregnant women for nausea, but medical experts warn against it. This concerns medical experts because marijuana use during pregnancy is linked to lower birth weight 10 and increased risk of both brain and behavioral problems in babies. If a pregnant woman uses marijuana, the drug may affect certain developing parts of the fetus's brain. Children exposed to marijuana in the womb have an increased risk of problems with attention, 11 memory, and problem-solving compared to unexposed children. 12 Some research also suggests that moderate amounts of THC are excreted into the breast milk of nursing mothers. 13 With regular use, THC can reach amounts in breast milk that could affect the baby's developing brain. Other recent research suggests an increased risk of preterm births. 27 More research is needed. Read our Marijuana Research Report for more information about marijuana and pregnancy.
• Intense nausea and vomiting. Regular, long-term marijuana use can lead to some people to develop Cannabinoid Hyperemesis Syndrome. This causes users to experience regular cycles of severe nausea, vomiting, and dehydration, sometimes requiring emergency medical attention. 14

Reports of Deaths Related to Vaping

The Food and Drug Administration has alerted the public to hundreds of reports of serious lung illnesses associated with vaping, including several deaths. They are working with the Centers for Disease Control and Prevention (CDC) to investigate the cause of these illnesses. Many of the suspect products tested by the states or federal health officials have been identified as vaping products containing THC, the main psychotropic ingredient in marijuana. Some of the patients reported a mixture of THC and nicotine; and some reported vaping nicotine alone. No one substance has been identified in all of the samples tested, and it is unclear if the illnesses are related to one single compound. Until more details are known, FDA officials have warned people not to use any vaping products bought on the street, and they warn against modifying any products purchased in stores. They are also asking people and health professionals to report any adverse effects. The CDC has posted an information page for consumers.

Mental Effects

Long-term marijuana use has been linked to mental illness in some people, such as:

• temporary hallucinations
• temporary paranoia
• worsening symptoms in patients with schizophrenia —a severe mental disorder with symptoms such as hallucinations, paranoia, and disorganized thinking

Marijuana use has also been linked to other mental health problems, such as depression, anxiety, and suicidal thoughts among teens. However, study findings have been mixed.

Are there effects of inhaling secondhand marijuana smoke?

Failing a drug test.

While it's possible to fail a drug test after inhaling secondhand marijuana smoke, it's unlikely. Studies show that very little THC is released in the air when a person exhales. Research findings suggest that, unless people are in an enclosed room, breathing in lots of smoke for hours at close range, they aren't likely to fail a drug test. 15,16 Even if some THC was found in the blood, it wouldn't be enough to fail a test.

Getting High from Passive Exposure?

Similarly, it's unlikely that secondhand marijuana smoke would give nonsmoking people in a confined space a high from passive exposure. Studies have shown that people who don't use marijuana report only mild effects of the drug from a nearby smoker, under extreme conditions (breathing in lots of marijuana smoke for hours in an enclosed room). 17

Other Health Effects?

More research is needed to know if secondhand marijuana smoke has similar health risks as secondhand tobacco smoke. A recent study on rats suggests that secondhand marijuana smoke can do as much damage to the heart and blood vessels as secondhand tobacco smoke. 20 But researchers haven't fully explored the effect of secondhand marijuana smoke on humans. What they do know is that the toxins and tar found in marijuana smoke could affect vulnerable people, such as children or people with asthma.

How Does Marijuana Affect a Person's Life?

Compared to those who don't use marijuana, those who frequently use large amounts report the following:

• lower life satisfaction
• poorer mental health
• poorer physical health
• more relationship problems

People also report less academic and career success. For example, marijuana use is linked to a higher likelihood of dropping out of school. 18 It's also linked to more job absences, accidents, and injuries. 19

Is marijuana a gateway drug?

Use of alcohol, tobacco, and marijuana are likely to come before use of other drugs. 21,22 Animal studies have shown that early exposure to addictive substances, including THC, may change how the brain responds to other drugs. For example, when rodents are repeatedly exposed to THC when they're young, they later show an enhanced response to other addictive substances—such as morphine or nicotine—in the areas of the brain that control reward, and they're more likely to show addiction-like behaviors. 23,24

Although these findings support the idea of marijuana as a "gateway drug," the majority of people who use marijuana don't go on to use other "harder" drugs. It's also important to note that other factors besides biological mechanisms, such as a person’s social environment, are also critical in a person’s risk for drug use and addiction. Read more about marijuana as a gateway drug in our Marijuana Research Report .

Can a person overdose on marijuana?

An overdose occurs when a person uses enough of the drug to produce life-threatening symptoms or death. There are no reports of teens or adults dying from marijuana alone. However, some people who use marijuana can feel some very uncomfortable side effects, especially when using marijuana products with high THC levels. People have reported symptoms such as anxiety and paranoia, and in rare cases, an extreme psychotic reaction (which can include delusions and hallucinations) that can lead them to seek treatment in an emergency room.

While a psychotic reaction can occur following any method of use, emergency room responders have seen an increasing number of cases involving marijuana edibles. Some people (especially preteens and teens) who know very little about edibles don't realize that it takes longer for the body to feel marijuana’s effects when eaten rather than smoked. So they consume more of the edible, trying to get high faster or thinking they haven't taken enough. In addition, some babies and toddlers have been seriously ill after ingesting marijuana or marijuana edibles left around the house.

Is marijuana addictive?

Marijuana use can lead to the development of a substance use disorder, a medical illness in which the person is unable to stop using even though it's causing health and social problems in their life. Severe substance use disorders are also known as addiction. Research suggests that between 9 and 30 percent of those who use marijuana may develop some degree of marijuana use disorder. 25 People who begin using marijuana before age 18 are four to seven times more likely than adults to develop a marijuana use disorder. 26

Many people who use marijuana long term and are trying to quit report mild withdrawal symptoms that make quitting difficult. These include:

• grouchiness
• sleeplessness
• decreased appetite

What treatments are available for marijuana use disorder?

No medications are currently available to treat marijuana use disorder, but behavioral support has been shown to be effective. Examples include therapy and motivational incentives (providing rewards to patients who remain drug-free). Continuing research may lead to new medications that help ease withdrawal symptoms, block the effects of marijuana, and prevent relapse.

Points to Remember

• Marijuana refers to the dried leaves, flowers, stems, and seeds from the Cannabis sativa or Cannabis indica plant .
• The plant contains the mind-altering chemical THC and other related compounds.
• People use marijuana by smoking, eating, drinking, or inhaling it.
• Smoking and vaping THC-rich extracts from the marijuana plant (a practice called dabbing ) is on the rise.
• altered senses
• impaired memory and learning
• hallucinations and paranoia
• breathing problems
• possible harm to a fetus's brain in pregnant women
• The amount of THC in marijuana has been increasing steadily in recent decades, creating more harmful effects in some people.
• It's unlikely that a person will fail a drug test or get high from passive exposure by inhaling secondhand marijuana smoke.
• There aren’t any reports of teens and adults dying from using marijuana alone, but marijuana use can cause some very uncomfortable side effects, such as anxiety and paranoia and, in rare cases, extreme psychotic reactions.
• Marijuana use can lead to a substance use disorder, which can develop into an addiction in severe cases.
• No medications are currently available to treat marijuana use disorder, but behavioral support can be effective.

For more information about marijuana and marijuana use, visit our:

• Marijuana webpage
• Drugged Driving DrugFacts
• Substance Abuse Center for Behavioral Health Statistics and Quality. Results from the 2018 National Survey on Drug Use and Health: Detailed Tables. SAMHSA. https://www.samhsa.gov/data/report/2018-nsduh-detailed-tables . Accessed December 2019.
• Miech, R. A., Johnston, L. D., Patrick, M. E., O’Malley, P. M., Bachman, J. G., & Schulenberg J. E. (2023). Monitoring the Future National Survey Results on Drug Use, 1975-2022 . Monitoring the Future Monograph Series. Ann Arbor: Institute for Social Research, The University of Michigan.
• Bell C, Slim J, Flaten HK, Lindberg G, Arek W, Monte AA. Butane Hash Oil Burns Associated with Marijuana Liberalization in Colorado. J Med Toxicol Off J Am Coll Med Toxicol. 2015;11(4):422-425. doi:10.1007/s13181-015-0501-0.
• Romanowski KS, Barsun A, Kwan P, et al. Butane Hash Oil Burns: A 7-Year Perspective on a Growing Problem. J Burn Care Res Off Publ Am Burn Assoc. 2017;38(1):e165-e171. doi:10.1097/BCR.0000000000000334.
• Meier MH, Caspi A, Ambler A, et al. Persistent cannabis users show neuropsychological decline from childhood to midlife. Proc Natl Acad Sci U S A. 2012;109(40):E2657-E2664. doi:10.1073/pnas.1206820109.
• Jackson NJ, Isen JD, Khoddam R, et al. Impact of adolescent marijuana use on intelligence: Results from two longitudinal twin studies. Proc Natl Acad Sci U S A. 2016;113(5):E500-E508. doi:10.1073/pnas.1516648113.
• Mehmedic Z, Chandra S, Slade D, et al. Potency trends of Δ9-THC and other cannabinoids in confiscated cannabis preparations from 1993 to 2008. J Forensic Sci. 2010;55(5):1209-1217. doi:10.1111/j.1556-4029.2010.01441.x.
• National Academies of Sciences, Engineering, and Medicine. The Health Effects of Cannabis and Cannabinoids: Current State of Evidence and Recommendations for Research. Washington, DC: The National Academies Press; 2017.
• Young-Wolff KC, Tucker L-Y, Alexeeff S, et al. Trends in Self-reported and Biochemically Tested Marijuana Use Among Pregnant Females in California From 2009-2016. JAMA. 2017;318(24):2490. doi:10.1001/jama.2017.17225
• The National Academies of Sciences, Engineering, and Medicine, Health and Medicine Division, Board on Population Health and Public Health Practice, Committee on the Health Effects of Marijuana: An Evidence Review and Research Agenda. The Health Effects of Cannabis and Cannabinoids: The Current State of Evidence and Recommendations for Research. http://nationalacademies.org/hmd/Reports/2017/health-effects-of-cannabis-and-cannabinoids.aspx . Accessed January 19, 2017.
• Goldschmidt L, Day NL, Richardson GA. Effects of prenatal marijuana exposure on child behavior problems at age 10. Neurotoxicol Teratol. 2000;22(3):325-336.
• Richardson GA, Ryan C, Willford J, Day NL, Goldschmidt L. Prenatal alcohol and marijuana exposure: effects on neuropsychological outcomes at 10 years. Neurotoxicol Teratol. 2002;24(3):309-320.
• Perez-Reyes M, Wall ME. Presence of delta9-tetrahydrocannabinol in human milk. N Engl J Med. 1982;307(13):819-820. doi:10.1056/NEJM198209233071311.
• Galli JA, Sawaya RA, Friedenberg FK. Cannabinoid Hyperemesis Syndrome. Curr Drug Abuse Rev . 2011;4(4):241-249.
• Röhrich J, Schimmel I, Zörntlein S, et al. Concentrations of delta9-tetrahydrocannabinol and 11-nor-9-carboxytetrahydrocannabinol in blood and urine after passive exposure to Cannabis smoke in a coffee shop. J Anal Toxicol. 2010;34(4):196-203.
• Cone EJ, Bigelow GE, Herrmann ES, et al. Non-smoker exposure to secondhand cannabis smoke. I. Urine screening and confirmation results. J Anal Toxicol. 2015;39(1):1-12. doi:10.1093/jat/bku116.
• Herrmann ES, Cone EJ, Mitchell JM, et al. Non-smoker exposure to secondhand cannabis smoke II: Effect of room ventilation on the physiological, subjective, and behavioral/cognitive effects. Drug Alcohol Depend. 2015;151:194-202. doi:10.1016/j.drugalcdep.2015.03.019.
• McCaffrey DF, Pacula RL, Han B, Ellickson P. Marijuana Use and High School Dropout: The Influence of Unobservables. Health Econ. 2010;19(11):1281-1299. doi:10.1002/hec.1561.
• Zwerling C, Ryan J, Orav EJ. The efficacy of preemployment drug screening for marijuana and cocaine in predicting employment outcome. JAMA. 1990;264(20):2639-2643.
• Wang X, Derakhshandeh R, Liu J, et al. One Minute of Marijuana Secondhand Smoke Exposure Substantially Impairs Vascular Endothelial Function. J Am Heart Assoc. 2016;5(8). doi:10.1161/JAHA.116.003858.
• Secades-Villa R, Garcia-Rodríguez O, Jin CJ, Wang S, Blanco C. Probability and predictors of the cannabis gateway effect: a national study. Int J Drug Policy. 2015;26(2):135-142. doi:10.1016/j.drugpo.2014.07.011.
• Levine A, Huang Y, Drisaldi B, et al. Molecular mechanism for a gateway drug: epigenetic changes initiated by nicotine prime gene expression by cocaine. Sci Transl Med. 2011;3(107):107ra109. doi:10.1126/scitranslmed.3003062.
• Panlilio LV, Zanettini C, Barnes C, Solinas M, Goldberg SR. Prior exposure to THC increases the addictive effects of nicotine in rats. Neuropsychopharmacol Off Publ Am Coll Neuropsychopharmacol. 2013;38(7):1198-1208. doi:10.1038/npp.2013.16.
• Cadoni C, Pisanu A, Solinas M, Acquas E, Di Chiara G. Behavioural sensitization after repeated exposure to Delta 9-tetrahydrocannabinol and cross-sensitization with morphine. Psychopharmacology (Berl). 2001;158(3):259-266. doi:10.1007/s002130100875.
• Hasin DS, Saha TD, Kerridge BT, et al. Prevalence of Marijuana Use Disorders in the United States Between 2001-2002 and 2012-2013. JAMA Psychiatry. 2015;72(12):1235-1242. doi:10.1001/jamapsychiatry.2015.1858.
• Winters KC, Lee C-YS. Likelihood of developing an alcohol and cannabis use disorder during youth: association with recent use and age. Drug Alcohol Depend. 2008;92(1-3):239-247. doi:10.1016/j.drugalcdep.2007.08.005.
• Corsi DJ, Walsh L, Weiss D, et al. Association Between Self-reported Prenatal Cannabis Use and Maternal, Perinatal, and Neonatal Outcomes. JAMA . Published online June 18, 2019322(2):145–152. doi:10.1001/jama.2019.8734

This publication is available for your use and may be reproduced in its entirety without permission from NIDA. Citation of the source is appreciated, using the following language: Source: National Institute on Drug Abuse; National Institutes of Health; U.S. Department of Health and Human Services.

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Know the Risks of Using Drugs

Drug use—including marijuana, cocaine, methamphetamine, as well as prescription drug misuse and illicit opioids—among adults is on the rise.

The COVID-19 pandemic has increased drug use.

Different drugs pose different dangers. Drug use can lead to dependence and addiction, injury and accidents, health problems, sleep issues, and more. Drug use affects you and those close to you. Know there is help.

Do you or someone you know hide their drugs?

Hiding Places

Download the audio and video files for "Hiding Places."

The Risks are Real

The pressures on adults are real. Building careers, buying homes, getting married, having kids, and trying to do it all well comes with a lot of pressure. COVID-19 has magnified the stress. Some turn to drugs to cope. Just because some drugs are legal, doesn’t mean they are less dangerous.

Over time, the regular or habitual use of drugs becomes a crutch and only adds to the stress. Drugs can also cause other harms, including:

• Cocaine: Highly addictive, cocaine is involved in nearly one in five overdose deaths; its health effects include asthma, bowel decay, and increased risk of HIV.
• Methamphetamine (Meth): Meth causes devastating health effects , and sometimes death, even on the first try. Meth speeds up the body’s systems to dangerous levels. Chronic users experience anxiety, confusion, insomnia, paranoia, aggression, and more.
• Prescription and illicit opioids: Highly addictive, the substances are the top cause of overdose deaths; health effects include confusion, nausea, constipation, coma, and brain damage.
• Marijuana: Even though it is legal in many states, studies link marijuana use to various negative outcomes .

Before the risks become real and before drugs turn your life—and your family—upside down, know there is help. You can quit.

The Rise of Drug Use for Adults Ages 26-49

While young adults ages 18-25 have the highest rates of drug use across the board, drug use among adults ages 26-49 is on the rise:

• The percentage of adults age 26 and older using marijuana daily or almost daily has nearly doubled since 2015.
• Cocaine use and death rates have risen; cocaine-involved overdose rates in the U.S. have risen annually since 2012.
• Meth use is on the rise and overdose death rates climbed more than five-fold for those ages 25 to 54 between 2011 and 2018.
• The nation remains in a prescription and illicit opioids crisis, as 81,230 drug overdose deaths occurred in the U.S.—the highest single year ever reported—in the 12 months ending in May 2020; most of the overdose deaths involved a prescription or illicit opioid.

If you, or someone you know, needs help with drug use or prescription drug misuse, call SAMHSA’s National Helpline at 1-800-662-HELP (4357) or TTY: 1-800-487-4889, or text your zip code to  435748 (HELP4U), or use SAMHSA’s Behavioral Health Treatment Services Locator to get help.

References and Relevant Resources:

• Early Serious Mental Illness Treatment Locator
• National Survey on Drug Use and Health | SAMHSA
• Step by Step Guides to Finding Treatment for Drug Use Disorders If Your Adult Friend or Loved One Has a Problem with Drugs | National Institute on Drug Abuse (NIDA)
• Drug Use and Addiction | Medline Plus
• Understanding Drug Use and Addiction DrugFacts | NIDA
• Prescription Opioids DrugFacts | NIDA
• Learn About Methamphetamine | SAMHSA
• Learn About Marijuana Risks | SAMHSA
• Resources for Families Coping with Mental and Substance Use Disorders | SAMHSA

Last Updated: 01/30/2024

What is Project 2025?

It’s a blueprint for what a second Trump administration could look like, dreamed up by his allies and former aides.

An update: Project 2025 just announced that it was going to stop creating policies, and that its director, a former Trump administration official, was leaving, The Washington Post’s Isaac Arnsdorf and Josh Dawsey report . Trump campaign, they report, is “furious” at the way Project 2025 has linked itself to Trump and how it has been received in the media. It’s not clear what that means for the initial 900-page plan, nor what it would mean for a second Trump presidency, since many of the ideas in Project 2025 are ideas Trump has endorsed and were put forward by close advisers or people who worked in his administration.

If Donald Trump struggled somewhat in his first administration to move the country dramatically to the right, he’ll be ready to go in a second term.

That’s the aim behind Project 2025, a comprehensive plan by former and likely future leaders of a Trump administration to remake America in a conservative mold while dramatically expanding presidential power and allowing Trump to use it to go after his critics.

The plan is gaining attention just as Trump is trying to moderate his stated positions to win the election, so he’s criticized some of what’s in it as “absolutely ridiculous and abysmal” and insisted that neither he nor his campaign had anything to do with Project 2025.

Still, what’s in this document is a pretty good indicator of what a second Trump presidency could look like. Here’s what Project 2025 is and how it could reshape America.

It’s a blueprint for a second Trump administration

The centerpiece is a 900-page plan that calls for extreme policies on nearly every aspect of Americans’ lives, from mass deportations, to politicizing the federal government in a way that would give Trump control over the Justice Department, to cutting entire federal agencies, to infusing Christian nationalism into every facet of government policy by calling for a ban on pornography and promoting policies that encourage “marriage, work, motherhood, fatherhood, and nuclear families.”

This isn’t coming directly from the Trump campaign. But it should be taken seriously because of the people who wrote it, analysts say. The main organization behind the plan, the Heritage Foundation, is a revolving door for Trump officials (and Heritage is a sponsor of the Republican National Convention, which will hand him the nomination next week).

“This is meant as an organized statement of the Trumpist, conservative movement, both on policy and personnel, and politics,” said William Galston, head of governance studies at the Brookings Institution.

2024 presidential election

Project 2025 calls for abortion limits, slashing climate change and LGBTQ health care funding, and much more

A few of the highlights:

Remake the federal workforce to be political : Instead of nonpartisan civil servants implementing policies on everything from health to education and climate, the executive branch would be filled with Trump loyalists. “It is necessary to ensure that departments and agencies have robust cadres of political staff,” the plan says. That means nearly every decision federal agencies make could advance a political agenda — as in whether to spend money on constituencies that lean Democratic. The project calls for cutting LGBTQ health programs, for example.

Cut the Education Department: Project 2025 would make extensive changes to public schooling, cutting longtime low-income and early education federal programs like Head Start, for example, and even the entire Education Department. “Federal education policy should be limited and, ultimately, the federal Department of Education should be eliminated,” the plan reads.

Give Trump power to investigate his opponents : Project 2025 would move the Justice Department, and all of its law enforcement arms like the FBI, directly under presidential control. It calls for a “top-to-bottom overhaul” of the FBI and for the administration to go over its investigations with a fine-toothed comb to nix any the president doesn’t like. This would dramatically weaken the independence of federal law enforcement agencies. “There’s going to be an all-out assault on the Department of Justice and the FBI,” said Galston, of Brookings. “It will mean tight White House control of the DOJ and FBI.”

Make reproductive care, particularly abortion pills, harder to get : It doesn’t specifically call for a national abortion ban, but abortion is one of the most-discussed topics in the plan, with proposals throughout encouraging the next president “to lead the nation in restoring a culture of life in America again.” It would do this by prosecuting anyone mailing abortion pills (“Abortion pills pose the single greatest threat to unborn children in a post-Roe world,” the plan says). It would raise the threat of criminalizing those who provide abortion care by using the government to track miscarriage, stillbirths and abortions, and make it harder to get emergency contraceptive care covered by insurance. It would also end federal government protections for members of the military and their families to get abortion care.

Crack down on even legal immigration : It would create a new “border patrol and immigration agency” to resurrect Trump’s border wall, build camps to detain children and families at the border, and send out the military to deport millions of people who are already in the country illegally ( including dreamers ) — a deportation effort so big that it could put a major dent in the U.S. economy. “Illegal immigration should be ended, not mitigated; the border sealed, not reprioritized,” the plan says.

Slash climate change protections : Project 2025 calls for getting rid of the National Oceanic and Atmospheric Administration, which forecasts weather and tracks climate change, describing it as “one of the main drivers of the climate change alarm industry.” It would increase Arctic drilling and shutter the Environmental Protection Agency’s climate change departments, all while making it easier to up fossil fuel production.

Ban transgender people from the military and consider reinstating the draft : “Gender dysphoria is incompatible with the demands of military service,” it reads. The author of this part of the plan led the Defense Department at the end of Trump’s presidency, and he told The Washington Post that the government should seriously consider mandatory military service.

How all of this would be implemented

A huge part of this project is to recruit and train people on how to pull the levers of government or read the law in novel ways to carry out these dramatic changes to federal policy. There’s even a place on the plan’s website where you can submit your résumé.

But there are some major hurdles to getting the big stuff done, even if Trump and Republicans win control of Washington next year. For one, Trump doesn’t appear to agree with everything in it. His campaign platform barely mentions abortion, while Project 2025 zeroes in on it repeatedly.

Also, some of these ideas are impractical or possibly illegal. Analysts are divided about whether Trump can politicize the civil workforce to fire them at will, for example. And the plan calls for using the military to carry out mass deportations on a historic scale , which could be constitutionally iffy.

Ominously, one of the project’s leaders opened the door to political violence to will all of this into being: “We are in the process of the second American revolution,” Heritage Foundation President Kevin Roberts warned recently, “which will remain bloodless, if the left allows it to be.”

Why Project 2025 is getting so much attention right now

It’s not unusual for wannabe administration officials to plan for how they’d govern once they get back in power. But what is unusual is how dramatic and unapologetically extreme many of these proposals are.

And the Biden campaign — which is obviously struggling right now with existential questions about its nominee — sees this as an easy target to campaign on.

Democrats are circulating a survey from a liberal organization that suggests talking about Project 2025 as a “takeover” of American government by Trumpists resonates with voters.

“It’s like reading a horror novel,” said Democratic strategist Jesse Ferguson. “Each page makes you want to read the next one, but when you finish reading it, you’re scared and disgusted.”

That’s much to the frustration of the Trump campaign, which doesn’t want such specific (and politically unpopular) ideas out there pegged to his campaign, as he’s trying to moderate some of his positions to win the election.

“It makes no sense to put all the crazy things you’ll be attacked for down on paper while you’re running,” a Trump adviser told The Washington Post recently .

But it’s fair to think of Project 2025 as a pretty good indicator of what a second Trump presidency would look like, analysts say.

“It’s not like Trump is going to hand out this booklet to his Cabinet on Day One and say, ‘Here you go,’” said Michael Strain, the director of economic policy studies at the conservative-leaning American Enterprise Institute. “But it reflects real goals of important people in Trump’s community.”

A previous version of this article misspelled the name of the American Enterprise Institute's Michael Strain as Michel. The article has been corrected.

Election 2024

Follow live updates on the 2024 election from our reporters on the campaign trail and in Washington.

Kamala Harris: A majority of Democratic delegates have pledged to support Harris , signaling she is likely to secure the presidential nomination next month. We broke down seven options for her vice-presidential pick .

Biden drops out: President Biden addressed the nation , seeking to define his legacy and explain his decision to exit the presidential race. Here’s what happened in the hours before Biden posted a letter announcing his decision to end his campaign .

Trump VP pick: Donald Trump has chosen Sen. JD Vance (Ohio) as his running mate , selecting a rising star in the Republican Party. But Vance has had a challenging start as the GOP’s vice-presidential nominee , leaving the Trump campaign to try to clean up his controversial past comments.

Presidential election polls: Here’s what voters think about Harris replacing Biden and how Harris performs against Trump in recent polls .

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Americans May Not Agree on Much, but They Agree Biden Made the Right Choice

The president’s decision to exit the race received overwhelming support. Only a few other things have drawn as much consensus in polling.

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By Francesca Paris and Ethan Singer

For once, American voters are in near total agreement about politics: They (almost) all agree that President Biden was right to exit the presidential race.

In the latest New York Times/Siena College poll , released on Thursday, 87 percent of registered voters approved of his decision to drop out. Only 9 percent disapproved.

Democrats and Republicans probably don’t agree for the same reasons: Republicans have generally always had negative views of the president, whereas many Democrats approved of his job performance but may have seen his exit as the most strategic path forward, or came to accept his decision once he made it.

Still, Mr. Biden’s move has reached a stratum of consensus that little in American public life can touch. We reviewed dozens of polls from the past few years, and it was hard to find anything that more people agreed on.

Note: Biden drop out and July 4 polls surveyed registered voters, while all other polls surveyed American adults. Sources: NYT/Siena poll (approval of Biden’s decision); Pew (restaurants, marijuana, small businesses, YouTube, age limits, haircuts, intelligent life); Gallup (George W. Bush, affairs, Russia, cloning, smartphones, God, divorce, same-sex marriage); Monmouth University (home decoration); CBS News (July 4); Fox News (best country); and Global Affairs (Kim Jong-un).

His exit is roughly as popular as small businesses , background checks for gun buyers and medical marijuana .

About 79 percent of American adults say there should be age limits for elected officials, making Mr. Biden’s decision, which revolved around age, more popular than age limits themselves.

What are some other things Americans have in common? A majority, but fewer than 87 percent, keep a smartphone near them during waking hours; watch fireworks on July 4; tip when getting a haircut ; support same-sex marriage ; care about climate change ; and decorate their home over the winter holidays.

What’s more popular than Mr. Biden’s choice, per the polls? Not a lot, but tipping at a sit-down restaurant ( 92 percent of Americans say they do this) is. And the vast majority of employed adults ( 91 percent ) said they were at least “somewhat” satisfied by their jobs.

In Times/Siena polling specifically, 87 percent is among the highest levels of agreement on any question in recent years. But we did find one comparable point of consensus: In a March 2024 survey, 88 percent of voters said prices for food and consumer goods were “only fair” or “poor.”

It’s not a surprising finding. Unhappiness with inflation seems to be one of the other broadly held views right now. (Pew Research Center found in May that 91 percent of Americans thought inflation was a moderately or very big problem .)

Polling suggests many Democrats didn’t want Mr. Biden to leave the race before he made his choice but came around to honoring his decision. In a Times/Siena poll of Pennsylvania voters two weeks ago, for example, just 46 percent of Democrats said Mr. Biden should drop out, while 48 percent said he should remain the candidate. But in this week’s poll , 91 percent of Democrats nationwide approved of his exit (as did 86 percent of Republicans and 85 percent of independents).

Mr. Biden said three weeks ago that he would quit the race only if “the Lord Almighty” told him to. In the end, a higher share of voters wound up supporting his exit than Americans who say they believe in God .

Ruth Igielnik and Christine Zhang contributed reporting.

Francesca Paris is a Times reporter working with data and graphics for The Upshot. More about Francesca Paris

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National Research Council (US) Committee on Substance Abuse and Habitual Behavior. An Analysis of Marijuana Policy. Washington (DC): National Academies Press (US); 1982.

An Analysis of Marijuana Policy.

• Hardcopy Version at National Academies Press

CONCLUSIONS

For the last decade, concern with health hazards attributable to marijuana has been rising. The hearts, lungs, reproductive functions, and mental abilities of children have been reported to be threatened by marijuana, and such threats are not to be taken lightly. Heavy use by anyone or any use by growing children should be discouraged. Although conclusive evidence is lacking of major, long-term public health problems caused by marijuana, they are worrisome possibilities, and both the reports and the a priori likelihood of developmental damage to some young users makes marijuana use a cause for extreme concern.

At the same time, the effectiveness of the present federal policy of complete prohibition falls far short of its goal--preventing use. An estimated 55 million Americans have tried marijuana, federal enforcement of prohibition of use is virtually nonexistent, and 11 states have repealed criminal penalties for private possession of small amounts and for private use. It can no longer be argued that use would be much more widespread and the problematic effects greater today if the policy of complete prohibition did not exist: The existing evidence on policies of partial prohibition indicates that partial prohibition has been as effective in controlling consumption as complete prohibition and has entailed considerably smaller social, legal, and economic costs. On balance, therefore, we believe that a policy of partial prohibition is clearly preferable to a policy of complete prohibition of supply and use.

We believe, further, that current policies directed at controlling the supply of marijuana should be seriously reconsidered. The demonstrated ineffectiveness of control of use through prohibition of supply and the high costs of implementing such a policy make it very unlikely that any kind of partial prohibition policy will be effective in reducing marijuana use significantly below present levels. Moreover, it seems likely to us that removal of criminal sanctions will be given serious consideration by the federal government and by the states in the foreseeable future. Hence, a variety of alternative policies should be considered.

At this time, the form of specific alternatives to current policies and their probable effect on patterns of use cannot be determined with confidence. It is possible that, after careful study, all alternatives will turn out to have so many disadvantages that none could command public consensus. To maximize the likelihood of sound policy for the long run, however, further research should be conducted on the biological, behavioral, developmental, and social consequences of marijuana use, on the structure and operation of drug markets, and on the relations of various conditions of availability to patterns of use.

• Cite this Page National Research Council (US) Committee on Substance Abuse and Habitual Behavior. An Analysis of Marijuana Policy. Washington (DC): National Academies Press (US); 1982. CONCLUSIONS.

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