THC concentration in category 5 medicinal cannabis products can range from 13% to 88%.
Category 5 cannabis products, which account for nearly half of all unapproved medicinal cannabis applications to the TGA, lack evidence for their safety or efficacy at THC concentrations above 22%, a rapid review published in Drug and Alcohol Review has found.
The research team from Monash Addiction Research Centre screened 9969 studies from the past decade for eligibility, but only 15 were included in the review, two of which were from Australia.
Of these, long-term efficacy implications were limited, with five of the studies using only a single dose.
Adverse events – predominantly dizziness, cough, nausea, drug highs and anxiety – were mild to moderate and tied to the total THC dose rather than its concentration.
Just two medicinal cannabis products have ever undergone pre-market TGA evaluation.
Since licensing began in 2016, Queensland has issued more medicinal cannabis prescriptions than all other states combined, with 167,000 scripts, compared with 156,000 across Victoria, NSW, WA and SA, according to AMA Queensland.
Over the past decade, more than 383,000 Special Access Scheme Category B prescription application approvals came from Queensland, followed by more than 354,000 from Victoria.
But these figures do not account for the authorised prescriber pathway, where Queensland still leads.
In an October 2025 submission to the TGA, AMA Queensland – alongside the RACGP, Pharmacy Guild and the Royal Australian and New Zealand College of Psychiatrists (RANZCP) – expressed concerns that the TGA’s current standards for regulating medicinal cannabis, including THC levels, were inadequate.
In a separate analysis published in RANZCP’s journal, more than half of the adverse events reported to the TGA from mid-2022 to mid-2025 were linked to category 5 products.
Psychiatric disorders, including anxiety, psychosis and paranoia, were the leading adverse event category for category five products, followed by nervous system and respiratory disorders.
In particular, the AMAQ said medicinal cannabis business models do not comply with the Medical Board of Australia’s telehealth guidelines and engage in direct-to-consumer marketing.
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AMAQ president Associate Professor Erica Gannon said the Drug and Alcohol Review study reaffirmed what the medical peaks have long maintained.
“[Medicinal cannabis] products are being prescribed for conditions for which there is no evidence of their efficacy or to patients with co-morbidities where medicinal cannabis is contraindicated,” Professor Gannon said.
The downflow effect, she said, is an increase in presentations of THC-induced psychosis and other harmful effects, further straining ED staff.
“We need governments to act against unscrupulous businesses and manufacturers putting profits from this industry ahead of people’s health,” the AMAQ president said.
Co-author of the study and Monash research excellence scholar Myfanwy Graham told The Medical Republic that there was very limited guidance on higher-THC medicinal cannabis products.
AHPRA’s own guidelines have warned against high-volume THC prescribing, failing to check real-time monitoring systems for other prescribed medicines, and conducting inappropriately short consultations.
“To prevent comorbidity and drug interactions, heightened screening and monitoring of patients is essential because we know not all information is being communicated from external telehealth or private clinics to GPs,” Ms Graham said.
Ms Graham said the TGA should consider setting THC concentration limits at the levels naturally occurring in the cannabis plant, between 30% and 35%, or even aligning with the 22% tested in randomised controlled trials.
AMAQ immediate past president Dr Nick Yim told TMR that, while a multitude of factors could be behind why Queensland’s prescribing and dispensing rates are disproportionately high, it was potentially related to a lack of interstate access to patients’ prescriptions.
“We want to ensure prescribers [have] specialist registration because we have heard many doctors who are in the telehealth models are in the non-specialist realm,” he said.
Eight practitioners have been flagged by AHPRA for issuing more than 10,000 scripts in a 6-month window, with one even issuing over 17,000.
In 2024, AHPRA established a national regulatory forum for medicinal cannabis, and the TGA is conducting a stakeholder consultation to inform regulatory reform.
The volume of medicinal cannabis units sold in Australia decreased by almost 30% following AHPRA and the TGA’s crackdown on dodgy medicinal cannabis prescribing, according to data from the Department of Health, Disability and Aging.
