Australians increasingly turn to medicinal cannabis for health issues, with around 700,000 people using it in the past year. Sales have quadrupled since 2022. However, most products lack registration with the Therapeutic Goods Administration, meaning they undergo limited testing for safety and efficacy.
Major Review Examines Effectiveness
The largest review of medicinal cannabis for mental health and substance use disorders analyzes 54 randomized controlled trials from 1980 to 2025. These trials, the gold standard for drug evaluation, target top prescription reasons: anxiety, sleep disorders, PTSD, insomnia, depression, and ADHD.
Results show minimal evidence that medicinal cannabis outperforms placebos for these conditions. Cannabidiol (CBD), the most studied cannabinoid, proves non-intoxicating and generally safe. Tetrahydrocannabinol (THC), which causes psychoactive effects, carries risks like short-term paranoia and long-term cannabis use disorder. Combinations of THC and CBD follow in study frequency.
Promising but Limited Results
Medicinal cannabis shows no advantage over placebos for psychotic disorders like schizophrenia, anxiety, PTSD, anorexia, or opioid use disorder. Yet, it reduces cannabis consumption in those with cannabis use disorder. Oral CBD-THC oils curb cravings, potentially lowering risks from high-THC smoking, such as lung problems.
Some studies hint at benefits for tics in Tourette’s syndrome, insomnia, and autism spectrum disorder. However, these involve few, low-quality trials. Intoxicating effects often unblind participants, introducing bias. Conflicts of interest further cloud results.
Safety Concerns Persist
Trials report mild side effects like nausea, dry mouth, and fatigue. Serious events, such as psychotic episodes, occur at rates similar to placebos. Studies average just five weeks, missing long-term harms from regular use.
One 2024 analysis indicates one-quarter of medicinal cannabis users develop use disorders, matching recreational rates. Australian products often feature high THC, unlike low-THC trial versions. Chronic high-THC intake worsens mental health, especially in youth.
Research Gaps and Real-World Mismatch
Prior reviews confirm these findings, often limited to fewer conditions or non-mental health uses like pain. Current evidence stems from short-term, CBD-focused trials, contrasting long-term, high-THC real-world patterns.
More long-term studies are essential, particularly for underserved conditions. As regulators assess prescribing practices, evidence should guide policy to prevent harm and promote proven treatments.
Key Advice for Users
Personal benefits do not contradict the evidence. Patients should consult doctors regularly and explore validated alternatives.
