The growing use of medicinal cannabis for mental health conditions is facing renewed scrutiny following a comprehensive review published in The Lancet Psychiatry. Researchers at the University of Sydney have found no evidence to support the effectiveness of medicinal cannabis – encompassing both cannabidiol (CBD) and tetrahydrocannabinol (THC) products – in treating anxiety, depression, or post-traumatic stress disorder (PTSD). This finding comes amidst a surge in prescriptions and sales of cannabinoid medications, particularly in Australia, raising questions about current prescribing practices and the need for more robust regulation.
Over the past four years, Australia has experienced a tripling in the sales of medicinal cannabis, with more than one million prescriptions approved as of February 2024, according to the Australian Health Practitioner Regulation Agency (AHPRA). This increase reflects a growing demand for alternative treatments for a range of conditions, including mental health disorders. However, the recent research challenges the rationale behind many of these prescriptions, suggesting that the routine use of medicinal cannabis for these conditions may be ineffective and potentially harmful.
Largest Review to Date Raises Concerns
The systematic review and meta-analysis, published in February 2026, analyzed data from 54 randomized controlled trials (RCTs) conducted over a 45-year period (1980-2025) worldwide. The study, led by Dr. Jack Wilson of the University of Sydney’s Matilda Centre for Research in Mental Health and Substance Use, represents the largest-ever investigation into the safety and efficacy of medicinal cannabis for mental health conditions. The researchers found a consistent lack of evidence supporting its use for anxiety, depression, and PTSD. The findings are available open access with a DOI of 10.1016/S2215-0366(26)00015-5.
Dr. Wilson emphasized the implications of these findings, stating that the approval of medicinal cannabis for these specific mental health conditions is now questionable. “Though our paper didn’t specifically look at this, the routine use of medicinal cannabis could be doing more harm than solid by worsening mental health outcomes, for example a greater risk of psychotic symptoms and developing cannabis use disorder, and delaying the use of more effective treatments,” he explained. This highlights the importance of evidence-based medicine and the potential risks associated with prescribing treatments without sufficient scientific backing.
Beyond Mental Health: Areas of Potential Benefit
While the study found no evidence of benefit for anxiety, depression, or PTSD, the researchers did identify some areas where medicinal cannabis may hold promise. The review suggested potential benefits in treating cannabis use disorder (cannabis dependency), autism, insomnia, and tics or Tourette’s syndrome. However, Dr. Wilson cautioned that the quality of evidence for these conditions was generally low. “But the overall quality of evidence for these other conditions, such as autism and insomnia, was low. In the absence of robust medical or counselling support, the use of medicinal cannabis in these cases [is] rarely justified,” he stated.
The research also confirmed existing evidence supporting the use of medicinal cannabis for specific medical conditions. These include reducing seizures associated with some forms of epilepsy, alleviating spasticity in individuals with multiple sclerosis, and managing certain types of pain. However, the study clearly delineates these established uses from the unsupported application for common mental health disorders. The findings regarding autism are particularly nuanced, with Dr. Wilson noting that the experience of autism is highly individual, and any potential benefits from medicinal cannabis should be interpreted with caution.
Potential Risks and the Case of Cocaine Dependence
The study also revealed potential risks associated with medicinal cannabis use, particularly in the context of substance abuse disorders. While it may be helpful in treating cannabis dependence – similar to how methadone is used for opioid dependence – the research found that medicinal cannabis actually increased cocaine cravings among individuals with cocaine-use disorder. “However, when medicinal cannabis was used to treat people with cocaine-use disorder, it increased their cravings. This means it should not be considered for this purpose and may, in fact, worsen cocaine dependence,” Dr. Wilson explained. This finding underscores the complex interplay between cannabis and other substances and the importance of careful consideration when prescribing it to individuals with a history of substance abuse.
The potential for adverse effects extends beyond substance use. The researchers also highlighted the risk of worsening mental health outcomes, including an increased risk of psychotic symptoms and the development of cannabis use disorder, particularly when used as a first-line treatment instead of established therapies. This concern is particularly relevant given the increasing accessibility of medicinal cannabis and the potential for self-medication without proper medical supervision.
Regulatory Review Underway in Australia
The findings of this study come at a critical time, as the Therapeutic Goods Administration (TGA) in Australia is currently reviewing the regulatory oversight of medicinal cannabis. The TGA initiated this review following the publication of over 500 responses to a public consultation in February 2026, as reported on the TGA’s consultation website: TGA Medicinal Cannabis Consultation. Dr. Wilson believes that the research provides valuable evidence to inform this review, supporting the need for evidence-based decision-making and ensuring patient safety.
“Our study provides a comprehensive and independent assessment of the benefits and risks of cannabis medicines, which may support the TGA and clinicians to make evidence-based decisions, helping to ensure patients receive effective treatments while minimising harm from ineffective or unsafe cannabis products,” Dr. Wilson stated. The TGA’s review is expected to address issues such as prescribing guidelines, product quality, and patient monitoring, with the aim of creating a more robust and responsible framework for the use of medicinal cannabis in Australia.
Implications for Global Healthcare
The implications of this research extend beyond Australia. The increasing global trend towards the legalization and medicalization of cannabis has led to a surge in its use for a wide range of conditions, often without sufficient scientific evidence. This study serves as a crucial reminder of the importance of rigorous research and evidence-based practice in healthcare. While medicinal cannabis may offer benefits for certain conditions, it is not a panacea, and its use should be carefully considered and monitored by qualified healthcare professionals.
The findings also highlight the need for further research into the long-term effects of medicinal cannabis, particularly on mental health. More studies are needed to understand the potential risks and benefits of different cannabinoids, dosages, and routes of administration. Research should focus on identifying which patients may be most likely to benefit from medicinal cannabis and which patients may be at higher risk of adverse effects.
As the landscape of medicinal cannabis continues to evolve, it is essential that healthcare professionals, policymakers, and patients have access to accurate and reliable information. This study provides a valuable contribution to that knowledge base, urging a more cautious and evidence-based approach to the use of medicinal cannabis for mental health conditions.
The TGA is expected to release its findings and proposed changes to the regulatory framework for medicinal cannabis in late 2026. Clinicians and patients are encouraged to stay informed about these developments and to rely on evidence-based guidelines when making decisions about treatment options. What are your thoughts on the findings of this study? Share your comments below, and let’s continue the conversation.