The information provided in this piece does not represent the views of the TGA or Expert Working Group.
Cannabis-related hospital admissions in Victoria rose by almost half in a decade, with psychosis the leading cause, new Monash University research has found.
The study analysed 39,565 cannabis-related admissions between July 2013 and June 2023, with psychotic disorders accounting for 4 in 10 admissions where cannabis was the main diagnosis. Admissions involving any cannabis diagnosis also rose by 50.4%.
Nationally, cannabis is now among the top five illicit drug classes for hospitalisations, with cannabis-related hospital admissions exceeding those for illicit opioids.
Lead author Myfanwy Graham – NHMRC Postgraduate Scholar, Monash University, Fulbright Alumna in Public Health Policy, and appointed member of the TGA’s Medicinal Cannabis Expert Working Group – said the findings ‘provide critical population-level insights that substantiate pharmacist, clinician and peak professional body concerns about increased cannabis-related psychosis’.
Psychosis leads admissions
Almost all cannabis-related admissions were due to mental and behavioural disorders (95.7%), with psychotic disorders the leading diagnosis where cannabis was the principal cause (40.1%).
Where patients were admitted for another condition but cannabis was also recorded, harmful use was the most common cannabis diagnosis (58.7%).
And many admissions were serious. Two-thirds involved stays of multiple days, while 1,592 admissions required intensive care.
Admissions peaked in 2020–21 at 77.3 per 100,000 people, with the COVID-19 pandemic a likely driver.
Ms Graham attributed the spike to ‘multiple factors, including COVID-19 pandemic disruptions, heightened mental health distress, and uninterrupted domestic supply chains’.
Harm rising faster in women
Young men aged 15–24 have the highest cannabis-related admission rates (36.9 per 100,000). But admissions among women have climbed significantly by 75.1% over a decade – more than double the rise in men.
The researchers link the jump to more women using cannabis, with past-year use among women rising from 7.6 to 9.8%, and to the pandemic, which impacted young women particularly hard.
‘Based on national data, more women are taking cannabis in high-risk ways, including more frequent use that can increase the risk of dependence,’ Ms Graham said.
Steepest rise in older Australians
People aged 65 and over made up less than 1% of admissions, but numbers rose more than 250% in older men and 400% in older women in this age cohort
Ms Graham said there are several things pharmacists need to take into account when dispensing medicinal cannabis scripts for older patients.
‘Older people may have a greater number of medications, such as anticoagulants, or comorbidities, including heart disease’ she said. ‘The body also changes how it processes medicines as we age. They may be at increased risk of drug- and disease-related interactions, necessitating careful checks during dispensing.’
She also called for tailored education approaches for older people, given the strength of prescribed products.
An Australian study estimated only a 1% increase in the THC content of illicit cannabis over the past decade, to an average of 12% – far lower than the concentrations of 88% or more THC available on prescription.
Vigilance when dispensing
Ms Graham pointed pharmacists to Therapeutic Goods Administration (TGA) guidance advising that medicinal cannabis containing THC is generally not appropriate for patients who:
- have a previous psychotic or concurrent active mood or anxiety disorder
- are pregnant, planning on becoming pregnant, or breastfeeding
- have unstable cardiovascular disease.
‘Cannabis-related hospitalisation study findings highlight additional vulnerable populations, including adolescents and young people (15–24 years), women, and older adults (65+ years),’ she said.
She said screening for high-risk use is essential, and that mental health screening and monitoring is important across all demographics.
The Australian Health Practitioner Regulation Agency has published guidance on the safe and appropriate supply of medicinal cannabis, including examples of poor practice.
‘These specify the need for pharmacists to counsel on safe and effective use,’ Ms Graham said.
The evidence base for the strongest products remains thin.
‘Based on a rapid review, there is no RCT [randomised controlled trial] evidence on the safety or efficacy of higher-THC medicinal cannabis products above 22% THC,’ she said. ‘There is a need for further research on safety considerations with higher strength products and cannabis dependence.’
Reporting adverse events
A separate study led by Ms Graham analysed more than 600 TGA medicinal cannabis adverse event case reports, covering 1,125 reactions from mid-2022 to 2025.
Higher THC-products (Category 5, with less than 2% CBD) were involved in 54.1% of reports. Psychiatric disorders such as anxiety, psychotic disorder and paranoia were among the most commonly reported reactions, along with nervous system and respiratory disorders.
But those reports only capture part of the picture.
‘Adverse events remain substantially underreported,’ Ms Graham said. ‘Unlike registered prescription medicines, the >1,000 unregistered medicinal cannabis products have not undergone formal pre-market safety evaluation by the TGA.’
She said pharmacists ‘can help fill the gaps in safety data for unregistered products’.
‘If an adverse event occurs, critical elements to document and report include dose, product details, concomitant medications and comorbidities, timelines, and outcomes.’
