Psychosis is an increasing risk of today’s strong marijuana.


  • Young adults and teens can develop an addiction to weed and become psychotic.
  • Many people don’t know that regular marijuana use may carry serious health risks, especially for the young.
  • No medication is FDA-approved for treating cannabis use disorder.
  • One cannabis-induced psychotic episode ups the risk of developing bipolar disorder or schizophrenia by 50%.

Most people don’t realize cannabis (marijuana, or “weed”) can be addictive and regular use may carry health risks such as stroke, heart attack, and mental illness, among others. Medical marijuana users may use the drug often or daily for chronic pain, and health problems are more common among frequent users. Yet most Americans see little problem with marijuana use.

In the United States, 22% of Americans 12 years of age or older, or 19 million people, used cannabis in 2022, with highest usage among those 18-25 years old (38%). In 2022, 30.7% of twelfth graders reported using cannabis in the past year, and 6.3% used cannabis daily in the past 30 days.

Cannabis use disorder (CUD) is also increasing; in 2022, 5.7 million people met diagnostic criteria for this disorder. The risk was highest (16.5%) among young adults ages 18-25. The core feature of the disorder is that users can’t stop using even though cannabis causes adverse consequences. Some people with CUD smoke marijuana multiple times every day, and many users are young men.

Marijuana is increasingly available in the United States because 38 states allow “medical marijuana” use by adults, and 24 states permit adult recreational use of cannabis. However, marijuana is categorized as a Schedule I illegal drug (with heroin and LSD) by the Drug Enforcement Administration (DEA). With widespread support for decriminalizing cannabis, the federal government generally looks the other way if they identify marijuana use in states that legalized marijuana.

It’s also important to know that the potency of today’s cannabis is very different from the product your grandparents may have used in the 1960s or ’70s. For example, modern marijuana products register an average of 15-20% tetrahydrocannabinol (THC, the psychoactive component of cannabis), with some products advertising 90% THC. In contrast, the average THC content of marijuana smoked at Woodstock back in 1969 had less than 1% THC.

The Yale School of Medicine recently announced that the Yale Center for the Science of Cannabis and Cannabinoids will investigate acute and chronic effects of cannabis and cannabinoids on human neurodevelopment and mental health. International expert Deepak Cyril D’Souza leads this organization. He noted, “Beyond the plant [are] a staggering array of other cannabis products with an even higher THC content, like dabs, oils, and edibles—some as high as 90%.”

Synthetic cannabinoids (SCs) are even more fraught with consequences. They target the endocannabinoid system in many body organs and can damage the normal functioning of brain and body systems. SC-related side effects are mediated by cannabinoid receptor 1 (CB1R) and cannabinoid receptor 2 (CB2R) activation, producing deleterious changes in the brain and body.

Cannabis Use Disorder

Numerous people use cannabis without adverse effects. However, for some, health risks associated with cannabis are real. About two-thirds of people diagnosed with CUD have at least one other substance use disorder, most commonly involving tobacco or alcohol. About half have a psychiatric disorder—most frequently post-traumatic stress disorder (PTSD), major depression, or generalized anxiety disorder. Having a psychiatric disorder is associated with more severe CUD.

Adolescents, Young People, and Cannabis Psychosis

The association between cannabis use and psychosis has been known for more than 100 years. Teens have report hallucinations or paranoia more often if they smoke marijuana at least once a month, versus those who smoke once or twice a year. Epidemiological studies and, more recently, genetic studies, suggest cannabis use is a risk for later development of psychosis. The association is complex and factors such as adolescent use, THC dose, past trauma, and other environmental risks, as well as psychiatric symptoms like anxiety and depression, may accelerate the process.

More potent cannabis and more frequent use contribute to higher rates of psychosis, especially in young people. Experiencing one cannabis-induced psychotic episode increases a person’s chance of bipolar disorder or schizophrenia by nearly 50%, significantly higher than a psychotic episode induced by amphetamines, hallucinogens, opioids. or alcohol.

Considering Other Health Risks of Cannabis

Since cannabis has been used widely without FDA approval for years, many consider it safe. Unfortunately, recent studies show that cannabis use can lead to cardiovascular diseases, pulmonary (lung) diseases, cancer, asthma, anhedonia, and psychiatric disorders.

Cardiovascular and Stroke Risks

Cannabis use often leads to increased heart rate in healthy individuals. Frequent cannabis smoking may also significantly increase the risk of heart attack and stroke. A study reported in the Journal of the American Heart Association examined nearly 435,000 American adults to explore the relationship between cannabis and cardiovascular events.

The study found daily use of cannabis—predominantly through smoking—increased the likelihood of heart attack by 25% and stroke 42% compared to non-use of the drug. Less frequent use was still associated with increased risks. Weekly users showed a 3% increased likelihood of heart attack and 5% increased likelihood of stroke.

Cardiologists warn that use of the drug has sobering consequences for the cardiovascular system, especially in those with unrecognized cardiovascular problems. “There are now higher rates of young people with no obvious cardiac histories going to the emergency room with heart attacks,” says Yale’s D’Souza. Many ER visits occur within an hour of the individual consuming cannabis.

Cannabinoid Hyperemesis Syndrome

Cannabinoid hyperemesis syndrome (CHS) is a form of cyclic vomiting often accompanied by abdominal pain. It may occur during or within 48 hours of frequent and heavy cannabis use. CHS is a major reason for cannabis-related visits to the ER.

The condition may also be present in those who mistakenly assume that edible marijuana (as in gummies or baked goods) has the same rapid effect as smoked marijuana. For example, an individual may consume cannabis orally to no effect for several hours, then eat extra edibles, causing toxicity to the digestive system.

Surgical Risks

Individuals should tell a surgeon and anesthesiologist if they use marijuana. The American College of Surgeons points out that marijuana may affect the level of pain medication needed after surgery. It may also be difficult for surgeons to place a breathing tube needed for anesthesia in regular marijuana users. Frequent use of the drug can also cause breathing difficulties, such as bronchitis. Surgeons recommend ending the use of all marijuana at least 72 hours before surgery.


For more than two decades, Dr. D’Souza has studied the relationship between cannabis use and psychosis. Cannabis may induce short-term psychotic disorder (cannabis-induced psychotic disorder, CIPD) lasting days to weeks. This condition often requires clinical intervention. In Denmark, increasing potency of cannabis has been associated with increased incidence of CIPD. Interestingly, up to 50% of patients diagnosed with CIPD were rediagnosed years later with schizophrenia or bipolar disorder, suggesting CIPD may predict a chronic psychotic disorder. Researchers also note that with more frequent and heavier use of the drug and higher potency cannabis, the risk of CIPD is greater.

Treatment of Cannabis Use Disorder

No medication is approved by the FDA for the treatment of CUD. However, GLP-1 drugs, currently used to treat type-2 diabetes and obesity, may help. A recent study suggests that semaglutide (Ozempic, Rybelsus, Wegovy) may reduce the risk of cannabis use disorder. The rate of CUD recurrence was only 13.0% in patients receiving semaglutide compared to 20.4% in those who did not, a 38% lower risk with semaglutide treatment.


As cannabis becomes increasingly available, individuals need to realize the possible risks associated with cannabis smoking, teen-young adult use, regular use of the drug, and high-THC products. Note that cocaine is considered safe and effective for ENT surgery, and fentanyl for pain relief and as an anesthetic. Similarly, marijuana and cannabinoids may have benefits. Having a specific FDA-approved use in medicine, prescribed and supervised by expert physicians, is one thing; we have learned the opposite from the cocaine epidemic of the 1980s and the current fentanyl overdose death crisis. Still, users need to be aware of health risks and remember that self-medication has additional risks. It was physician Sir William Osler, a founder of Johns Hopkins Hospital, who first observed, “A physician who treats himself has a fool for a patient.” A patient who treats himself should be aware, as well.


Gorelick DA. Cannabis-Related Disorders and Toxic Effects. N Engl J Med. 2023 Dec 14;389(24):2267-2275. doi: 10.1056/NEJMra2212152. PMID: 38091532.

Jeffers AM, Glantz S, Byers AL, Keyhani S. Association of Cannabis Use With Cardiovascular Outcomes Among US Adults. J Am Heart Assoc. 2024 Mar 5;13(5):e030178. doi: 10.1161/JAHA.123.030178. Epub 2024 Feb 28. PMID: 38415581; PMCID: PMC10944074.

Burnett GM, Ganesh S, D’Souza DC. Cannabis and Psychosis: Recent Epidemiological Findings Continuing the “Causality Debate”. Am J Psychiatry. 2022 Jan;179(1):8-10. doi: 10.1176/appi.ajp.2021.21111126. PMID: 34974754.

Hill KP, et. al. Risks and Benefits of Cannabis and Cannabinoids in Psychiatry. Am J Psychiatry. 2022 Feb;179(2):98-109. doi: 10.1176/appi.ajp.2021.21030320. Epub 2021 Dec 8. PMID: 34875873.