In 2018, high-profile campaigns advocating for children with treatment-resistant epilepsy resulted in the legalization of medical cannabis in the UK. This legal change authorized specialist consultants to prescribe cannabis-based products for medicinal use (CBPMs) for any condition deemed in the best interests of the patient. However, without a prescription, the possession and use of cannabis, classified as a Class B drug, remain illegal in the UK.
Despite the law permitting prescriptions, most CBPMs are unlicensed, lacking market authorization from the Medicines and Healthcare Products Regulatory Agency (MHRA), and are rarely prescribed through the NHS. Consequently, a private market has emerged, with over 30 specialized cannabis clinics registered with the Care Quality Commission in England. These clinics are reportedly prescribing CBPMs to approximately 80,000 patients, addressing a range of conditions from chronic pain to anxiety and ADHD. Data indicates that nearly half of these prescriptions are for psychiatric conditions, mirroring trends seen in Australia and the US.
Review of Cannabinoids’ Efficacy
However, a recent review published in Lancet Psychiatry analyzed over 50 randomized control trials (RCTs) and found “no evidence” supporting the benefits of cannabinoids for treating anxiety, PTSD, substance-use disorders, ADHD, bipolar disorder, psychotic disorders, or anorexia. While some evidence suggests efficacy in conditions like cannabis-use disorder, insomnia, Tourette’s syndrome, and autism spectrum disorder, this was deemed of “low quality.”
As this study emerges, the Advisory Council for the Misuse of Drugs (ACMD) is reviewing medical cannabis prescribing in the UK, looking into potential “unintended consequences” of the legal changes. Former ACMD chair Prof. Owen Bowden-Jones noted that the findings hint that the benefits of medical cannabis “may have been overstated for many conditions.” He emphasized the need for high-quality research to better understand cannabis’s effects.
Treatment Options and Patient Experiences
Dr. Niraj Singh, a consultant psychiatrist who has been prescribing medical cannabis for over six years, argues that the absence of evidence does not equate to the absence of efficacy. He cites numerous patient testimonies highlighting the benefits of cannabis across various symptoms. Many patients turn to medical cannabis after exhausting conventional treatment options, often struggling to access adequate mental health support.
In January 2026, over 1.5 million adults were reportedly in contact with NHS mental health services, with 8.7 million in England prescribed antidepressants, which are effective in approximately three-quarters of cases. A respondent from a survey by the medical cannabis advocacy group United Patients Alliance expressed relief at finding a treatment that works for them without the harmful side effects associated with previous prescriptions.
Despite claims of safety and efficacy from some advocates, there is a recognized concern regarding the side effects of cannabis, which can include increased anxiety and paranoia. Research suggests that patients with a history of mental health disorders may be at higher risk when using products with higher THC content. Observational evidence linking cannabis use to symptom improvement in conditions like PTSD and OCD exists; however, these studies were not included in the recent review.
The Need for Rigorous Research
Prof. David Nutt, former chair of the ACMD and founder of the independent charity Drug Science, argues that RCTs should not be the sole metric for determining the efficacy of cannabis as a medicine. He advocates for the incorporation of real-world evidence, which can provide valuable clinical data not always captured in controlled trials. Moreover, the complexities of cannabis—a plant containing hundreds of active compounds—pose challenges for traditional clinical trial designs.
Concerns have also been raised regarding the prescribing practices in cannabis clinics, particularly in complex cases involving significant mental health histories. The Medical Cannabis Clinicians Society suggests a more structured approach to oversight, recommending peer reviews for higher dosages and rigorous monitoring. There is a consensus among prescribers that the current processes require tightening to ensure patient safety and appropriate use.
As the debate over the efficacy of medical cannabis continues, the ongoing lack of robust clinical trials presents significant challenges. The regulatory environment remains complex, and the need for comprehensive research is paramount. While the legal landscape has changed, many patients fear being pushed back into the illegal market where they lack access to regulated products and medical oversight.
Advocates for medical cannabis argue that dismissing its potential based on incomplete evidence is detrimental to patients who rely on its therapeutic benefits. They stress the urgent need for real-world evidence studies and comprehensive research into treatment-resistant populations to bridge the existing knowledge gap.