For years, cannabis has been prescribed and promoted as a natural remedy for some of the most common mental health struggles people face. But a sweeping new analysis is raising serious doubts about that practice and experts say the findings deserve close attention.
What the study examined
Researchers at the University of Sydney in Australia reviewed 54 randomized controlled trials conducted between 1980 and 2025, all of which looked at cannabinoids the active compounds found in cannabis as a primary treatment for mental health and substance-use disorders. The study included data from 2,477 participants, 69% of whom were male, with an average age of 33. The findings were published in The Lancet Psychiatry.
The analysis concluded that cannabis-based treatments are rarely justified for routine use in mental health care. More concerning, participants who used cannabinoids faced roughly 75% higher odds of experiencing adverse side effects compared to those who did not.
The conditions where cannabis came up short
Depression, anxiety and PTSD are among the leading reasons cannabis products are prescribed in the United States, the United Kingdom and Australia. Yet the researchers found no evidence to suggest cannabinoids are effective in treating any of these three conditions.
The analysis also found no significant benefit for psychotic disorders, opioid use disorder or anorexia nervosa. Researchers did not find enough data to draw conclusions about ADHD, bipolar disorder, OCD or tobacco use disorder, and no randomized trials focused on depression met the criteria for inclusion in the review.
A small number of results showed some potential for treating cannabis use disorder itself, insomnia, Tourette’s symptoms and certain autistic traits though the researchers characterized the quality of that evidence as low.
It is worth noting that the study did confirm cannabis has demonstrated benefits in other medical contexts, including reducing epileptic seizures, easing multiple sclerosis symptoms and managing certain types of pain.
What experts say about the findings
Thea Gallagher, a clinical associate professor in the department of psychiatry at NYU Grossman School of Medicine who was not involved in the study, described the review as the most comprehensive effort to date to evaluate cannabis specifically for anxiety, depression and PTSD. She noted that earlier research often relied on self-reported symptoms or observational data that cannot establish cause and effect, and that many prior studies used synthetic cannabinoids or low-THC formulations that do not reflect the products widely available today.
Gallagher emphasized that while cannabis does have legitimate medical uses, mental health conditions are not reliably among them at this time. She cautioned that using cannabis to manage emotional distress may push people away from treatments that are actually proven to work and that individuals with a personal or family history of psychosis should be particularly careful.
Signs that cannabis may be doing more harm than good
Mental health professionals advise anyone using cannabis to pay close attention to shifts in mood, motivation, sleep quality, anxiety levels, concentration and social engagement. Red flags worth watching for include needing increasingly higher doses to feel the same effect, relying on cannabis as a way to cope with stress, experiencing greater paranoia or persistent mental fogginess. Checking in with a trusted friend or family member and taking occasional breaks from use can help clarify whether cannabis is genuinely helping or simply masking deeper issues.
Why people still turn to cannabis for mental health
Jessica Watrous, a clinical psychologist and chief clinical officer at Modern Health in California, who also had no involvement in the study, pointed to a broader problem: mental health care in the U.S. can be expensive, difficult to navigate and hard to access. It is understandable, she noted, that people look for faster, more available ways to manage how they are feeling.
The concern, however, is that reaching for a less evidence-backed option may delay getting the kind of support that does have strong clinical backing whether that is therapy, coaching, meditation or consistent daily self-care practices.
Anyone whose mood or day-to-day functioning begins to decline is encouraged to seek professional support rather than adjusting their cannabis use on their own.
