To assess the true impact of cannabinoids on mental health, researchers conducted the largest analysis to date, examining both the safety and effectiveness across a wide range of conditions. The study reviewed 54 randomized controlled trials spanning 45 years, involving thousands of participants worldwide. The scale and rigor of this research make its conclusions hard to ignore.
No evidence that medicinal cannabis helps anxiety, depression, or PTSD
The key result from the study is very clear. Medicinal cannabis does not effectively treat anxiety, depression, or PTSD. In some cases, it may even worsen mental health outcomes.
Lead author Dr. Jack Wilson from the University of Sydney’s Matilda Centre warns, “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 evidence for some conditions
The study did find some indications that medicinal cannabis might help with cannabis use disorder, autism, insomnia, and tics or Tourette’s syndrome. However, Dr. Wilson emphasized that the supporting evidence for these uses is not strong.
“The overall quality of evidence for these other conditions, such as autism and insomnia, was low. In the absence of robust medical or counselling support, the use of medicinal cannabis in these cases is rarely justified.”
He added, “There is, however, evidence that medicinal cannabis may be beneficial in certain health conditions, such as reducing seizures associated with some forms of epilepsy, spasticity among those with multiple sclerosis, and managing certain types of pain, but our study shows the evidence for mental health disorders falls short.”
Mixed results for substance use disorders
The review also examined how medicinal cannabis affects different substance use disorders. Results varied depending on the condition.
Cannabis-based treatments showed some potential for helping people with cannabis dependence. However, the study found a concerning effect in people with cocaine-use disorder, where cannabis use increased cravings.
“Similar to how methadone is used to treat opioid-use disorder, cannabis medicines may form part of an effective treatment for those with a cannabis-use disorder,” Dr. Wilson said. “When administered alongside psychological therapy, an oral formulation of cannabis was shown to reduce cannabis smoking.”
“However, when medicinal cannabis was used to treat people with cocaine-use disorder, it increased their cravings. This means it should not be considered for this purpose and may, in fact, worsen cocaine dependence.”
Calls for stronger regulation
The rapid rise in medicinal cannabis use and prescribing has raised concerns among major medical organizations, including the American Medical Association. Experts point to limited regulation and ongoing uncertainty about how effective and safe these products really are.
“Our study provides a comprehensive and independent assessment of the benefits and risks of cannabis medicines, which may support clinicians to make evidence-based decisions, helping to ensure patients receive effective treatments while minimizing harm from ineffective or unsafe cannabis products,” Dr. Wilson said.
As the debate continues, one thing is clear: the promise of medicinal cannabis for mental health may not yet match the reality.
