A new large-scale review is raising questions about the effectiveness of marijuana for treating mental health conditions, with researchers concluding its use is “rarely justified.”
About half of Americans who use cannabis for medical purposes say they rely on it to manage symptoms such as anxiety, depression and PTSD. However, the latest analysis, the largest review of medicinal cannabis to date, found little evidence that it effectively treats most mental health or substance use disorders.
Researchers also warned cannabis use could worsen some conditions, increasing the risk of psychosis and addiction while potentially delaying access to proven treatments.
The findings are based on an analysis of 54 clinical trials involving nearly 2,500 participants worldwide over a 45-year period from 1980 to 2025.
The review found no meaningful benefit of cannabinoids for a wide range of conditions, including opioid, tobacco and cocaine use disorders, as well as bipolar disorder, anxiety, ADHD, psychotic disorders, PTSD, OCD and anorexia nervosa.
Some limited benefits were identified. Researchers found cannabinoids were associated with reduced withdrawal symptoms and decreased use among people with cannabis use disorder. There was also some evidence of reduced insomnia symptoms and modest improvements in sleep.
In addition, a reduction in tic severity was observed, but only in cases where cannabidiol (CBD) and THC were used together. Researchers also noted a possible reduction in autistic traits, though they emphasized the evidence was of very low certainty and based on studies with a high risk of bias.
Overall, participants who received cannabinoids were more likely to experience adverse effects compared to those given a placebo. Researchers found that for every seven people treated with cannabinoids, one experienced an adverse event that would not have occurred with a placebo.
Researchers say more study is needed, but current evidence does not support widespread use of cannabis for mental health treatment.
The findings add to a growing body of research raising concerns about marijuana use. Previous studies have linked frequent use to lasting effects on working memory, a significantly increased risk of schizophrenia in young men, and a higher risk of premature death among those hospitalized for cannabis use disorder.
In a previous episode of Grieving Out Loud, Laura Stack shared why she believes cannabis-induced psychosis contributed to her son’s death.
“He said, ‘You probably don’t remember, but you told me many years ago that marijuana would hurt my brain, and it’s ruined my mind and my life. I am so sorry, Mom. I love you,’” Stack said.
Stack now works to raise awareness about the risks of marijuana on the developing brain through her nonprofit, Johnny’s Ambassadors.
