A major review published in The Lancet Psychiatry concludes that medicinal cannabis does not effectively treat anxiety, depression or post-traumatic stress disorder. The analysis of 54 randomized controlled trials over 45 years found limited evidence for other conditions like insomnia and autism. Researchers warn of potential harms including psychosis risk and delayed effective treatments.
The largest review to date on cannabinoids for mental health conditions, published in The Lancet Psychiatry, reports no effective treatment for anxiety, depression or PTSD. Led by Dr. Jack Wilson from the University of Sydney's Matilda Centre, the study examined safety and effectiveness across various disorders using data from 54 randomized controlled trials spanning 1980 to 2025. About 27 percent of people aged 16-65 in the United States and Canada report medical cannabis use, with half citing mental health symptoms as the reason. Dr. Wilson stated, 'Though our paper didn't specifically look at this, the routine use of medicinal cannabis could be doing more harm than good by worsening mental health outcomes, for example a greater risk of psychotic symptoms and developing cannabis use disorder, and delaying the use of more effective treatments.' Limited indications of benefit appeared for cannabis use disorder, autism, insomnia and tics or Tourette's syndrome, though evidence quality remains low. Dr. Wilson noted, 'In the absence of robust medical or counseling support, the use of medicinal cannabis in these cases are rarely justified.' For substance use disorders, cannabis-based treatments showed potential for cannabis dependence when combined with psychological therapy, but increased cravings in cocaine-use disorder cases. The review confirms benefits for epilepsy-related seizures, multiple sclerosis spasticity and certain pain types, but not mental health. Funded by the NHMRC, the findings support evidence-based clinical decisions amid rising medicinal cannabis use and calls for stricter regulation from groups like the American Medical Association.
