New research from the University of Sydney indicates that there’s minimal strong evidence supporting the use of medicinal cannabinoids for mental health issues or substance use disorders. The study involved a review of 54 randomized controlled trials from 1980 to 2025, focusing on the use of cannabinoids, the active compounds in cannabis, as a primary treatment. A total of 2,477 participants were included, predominantly male, with a mean age of around 33 years. The findings were published in The Lancet Psychiatry.
Interestingly, while many cannabis products are prescribed in countries like the U.S., UK, and Australia for conditions such as depression, anxiety, and PTSD, the researchers found no substantial evidence that these products effectively treat such conditions. Cannabis treatments appeared “hardly justified” for regular use and posed a roughly 75% higher risk of adverse side effects.
Some aspects of the study did show potential for treating disorders like cannabis use disorder, insomnia, Tourette syndrome, and traits associated with autism, although the quality of this evidence was deemed low. In terms of anxiety disorders, psychotic disorders, PTSD, opioid use disorder, or anorexia nervosa, cannabinoids showed no significant impact.
There’s a noted lack of sufficient data regarding cannabis’s effects on ADHD, bipolar disorder, OCD, or smoking addiction, and notably, no randomized trials examining depression met the criteria for the review. Dr. Jack Wilson, the lead author, emphasized that these results urge a reconsideration of medical cannabis approval for mental health issues such as depression, anxiety, and PTSD, remarking that excessive reliance on medical cannabis could even worsen mental health outcomes.
He elaborated that daily use of medical cannabis might increase the risk of developing psychotic symptoms or cannabis use disorder, possibly delaying access to more effective treatments. However, researchers did recognize the benefits of medicinal cannabis for certain conditions like epileptic seizures, symptoms related to multiple sclerosis, and specific pain types.
Dr. Thea Gallagher, a clinical associate professor at New York University’s Grossman School of Medicine, discussed the importance of this study compared to previous smaller studies, noting that earlier research often relied on self-reported symptoms and struggled to establish causality. She pointed out that the current review is a comprehensive effort to evaluate cannabis concerning anxiety, depression, and PTSD.
While Gallagher acknowledged that cannabis has legal medical applications, she cautioned that mental health conditions might not necessarily fit these uses. She warned that relying on cannabis for mental distress could hinder timely access to proven treatments. Users should monitor changes in their mood, motivation, sleep, and social interactions over time, she advised.
Dr. Jessica Watros, another expert not involved in the study, highlighted the reasons people might turn to cannabis for symptom management, particularly given the financial and accessibility barriers in mental health care. She echoed the need to utilize evidence-backed interventions rather than relying solely on less supported methods, which may ultimately delay effective help.
Watros stressed the importance of prioritizing mental health, encouraging proactive engagement with tools like therapy, meditation, and daily self-care practices.
Finally, the review noted several limitations, such as a high risk of bias in around 44% of the studies and variability in product types, doses, and patient demographics. This added complexity to the interpretation of results, as real-world cannabis use often involves different dosages and sometimes combinations with other substances.
