Australian Doctors Prescribe High-THC Medicinal Cannabis: Study 2026

Australian doctors are commonly prescribing high-THC medicinal cannabis with concentrations up to four times those tested in clinical trials, according to a new Monash University study. This practice raises serious questions about patient safety and the evidence base for such products.

Study Reveals Mismatch Between Prescriptions and Evidence

Researchers from Monash University evaluated available evidence for the efficacy and safety of higher THC potency medicinal cannabis products commonly used in Australia. They found that only products containing up to 22% THC have been tested in randomised controlled trials, yet many prescribed products contain up to 88% THC.

What Is THC?

THC (delta-9-tetrahydrocannabinol) is the main psychoactive ingredient in cannabis. In Australia, there is no upper limit for THC concentration in medicinal cannabis products. Category 5 products—dried herb and concentrated extracts—range from 13% to 88% THC.

Key Findings

• Over 1,000 medicinal cannabis products are available, but only two have undergone pre-market evaluation by the Therapeutic Goods Administration (TGA) for quality, safety, and efficacy.
• Products prescribed often contain 4x the THC levels tested in clinical trials.
• Professor Suzanne Nielsen from Monash Addiction Research Centre warns of a "real mismatch" between evidence and prescribing practices.

Comparison of THC Levels

Expert Recommendations

Professor Nielsen suggests the TGA should consider setting THC concentration limits at or below naturally occurring levels (about 35%), or even at 22% in line with tested products. She also calls for better labelling, health warnings, and improved monitoring of harms.

Consumer Awareness

The study notes that it is unclear how well consumers understand the products they are using. Many may not realise the potency or risks associated with high-THC medicinal cannabis.

Implications for Australian Patients

Patients prescribed high-THC cannabis may face unknown side effects and uncertain efficacy. The findings, published in Drug and Alcohol Review, urge regulators to prioritise patient safety over profit.

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