A Monash University review finds doctors are prescribing high-THC cannabis products that lack clinical evidence, raising concerns about patient safety and profit-driven practices.
Key facts
- •Category 5 medicinal cannabis products in Australia can contain up to 88% THC.
- •Only two of the more than 1,000 available medicinal cannabis products have undergone TGA pre-market evaluation.
- •Clinical trials have only assessed the efficacy of medicinal cannabis products with THC concentrations up to 22%.
- •An Ahpra review found some practitioners issued more than 10,000 high-strength THC prescriptions in a six-month period.
- •Adverse event reports linked to category 5 products include psychosis, suicidal behavior, and cannabis hyperemesis syndrome.
A review by Monash University researchers has found that medicinal cannabis products prescribed in Australia frequently contain THC concentrations up to four times higher than those tested in clinical trials. The study, published in the journal Drug and Alcohol Review, highlights a significant gap between the products being used by patients and the available scientific evidence regarding their efficacy and safety.
By the numbers
Lack of Regulatory Oversight and Evidence
In Australia, there is no upper limit for THC concentration in medicinal cannabis. Products categorized as 'category 5'—which include dried herbs and concentrated extracts—range from 13% to 88% THC. Despite over 1,000 products being available, only two have undergone pre-market evaluation by the Therapeutic Goods Administration (TGA) for quality, safety, and efficacy. Prof. Suzanne Nielsen of the Monash Addiction Research Centre noted that clinical trials have only assessed products containing up to 22% THC, leaving high-concentration products largely unstudied.
Concerns Over Prescribing Practices
Data from the TGA indicates that chronic pain and anxiety are the primary drivers for prescriptions, with category 5 products accounting for half of all approvals. Dr. Jack Wilson of the University of Sydney noted that research does not support the efficacy of these products for anxiety, and evidence for chronic pain remains low-quality. A 2025 review by the Australian Health Practitioner Regulation Agency (Ahpra) identified practitioners who issued over 10,000 prescriptions for high-strength THC products in six months, sometimes following consultations lasting only seconds. Experts, including Dr. Michael Wright of the Royal Australian College of General Practitioners, have expressed concern that telehealth clinics and direct-to-consumer marketing are prioritizing profits over patient safety.
Reported Adverse Health Effects
Between mid-2022 and mid-2025, the TGA received 614 adverse event reports related to medicinal cannabis, with half involving category 5 products. Reported harms include psychosis, cannabis hyperemesis syndrome, and suicidal behavior. While a report does not confirm the product caused the symptoms, Dr. Wilson warned that regular high-THC consumption carries risks of both short- and long-term harm, potentially worsening a patient's underlying condition.
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This article was independently rewritten by ManyPress editorial AI from reporting originally published by The Guardian Health.
