In 2018, high-profile campaigns on behalf of children with treatment-resistant epilepsy led to the legalisation of medical cannabis in the UK.

In the dimly lit waiting room of a private cannabis clinic in London, a mother clutches an outdated prescription for traditional antidepressants, her fingers trembling as she recounts how her eighteen-year-old daughter spiraled into a crippling depression after losing a close friend. “We tried everything,” she whispers, barely containing her tears. “For her, medical cannabis was a last resort, yet it’s been a lifeline.” As public awareness about the benefits of cannabis-based products for medicinal use (CBPMs) has grown, so too has a complex web of expectations, evidence, and regulation surrounding its prescription in the UK.

Since 2018, when high-profile campaigns galvanized public support for legalizing medical cannabis, specialist consultants have been allowed to prescribe these products for various medical conditions. However, the reality is more complicated: despite being a Class B drug, cannabis can be prescribed in circumstances deemed beneficial for patients. Yet, most products remain unlicensed, lacking the necessary market approval from the Medicines and Healthcare Products Regulatory Agency (MHRA). As a result, the UK’s National Health Service (NHS) rarely prescribes these medications, leading to the emergence of a private market catering to an estimated 80,000 patients.

These patients seek relief from a multitude of ailments—from chronic pain to anxiety and ADHD—amidst growing public and medical interest. Remarkably, data indicate that around 42% of patients are prescribed medical cannabis for psychiatric conditions, mirroring trends in Australia and the United States.

However, a recent review published in The Lancet Psychiatry systematically examined over 50 randomized controlled trials (RCTs) and found “no evidence” supporting the efficacy of cannabinoids in treating anxiety, PTSD, substance-use disorders, ADHD, bipolar disorder, psychotic disorders, or anorexia. While evidence exists for low-quality efficacy in specific cases like cannabis-use disorder and insomnia, this has raised an essential question: Why is cannabis prescribed when the scientific backing is scant?

Treatment options

“The absence of evidence isn’t evidence of absence,” asserts Dr. Niraj Singh, a consultant psychiatrist who has been prescribing medical cannabis for over six years. “Tens of thousands of patients would attest to its benefits across an array of symptoms.” In 2026, more than 1.5 million adults sought help from NHS mental health services, reflecting the rising crisis of untreated psychiatric conditions. “For many, conventional treatments have failed,” Singh explains.

• Over 1.5 million adults were involved with NHS mental health services as of January 2026.
• According to 2023/24 estimates, 8.7 million people in England were prescribed antidepressants.
• 42% of patients using CBPMs report mental health issues like anxiety and depression.

In a survey conducted by the advocacy group United Patients Alliance, one participant described feeling “seen and supported” after switching to medical cannabis, voicing a common sentiment that traditional medications often come with adverse side effects. “People hit a ceiling regarding their treatment options,” Singh notes. “For them, medicinal cannabis has worked.” This highlights a crucial gap: while RCTs often exclude real-world experiences, observational studies present a different narrative, indicating improvements in symptoms. Nonetheless, these types of studies lack the robust framework RCTs provide due to their susceptibility to bias.

Former chair of the Advisory Council for the Misuse of Drugs (ACMD), Prof. Owen Bowden-Jones, mentioned the need for more research to understand the full implications of cannabis use. “The current review indicates that benefits may have been overstated,” he stated, urging for a more careful approach to prescribing.

Clinical oversight

While medical cannabis is not free of side effects, including increased anxiety and paranoia, it is not uniformly harmful. Research published in BMJ Mental Health highlights concerns regarding self-medication habits, wherein those with pre-existing conditions may consume higher THC levels, intensifying their symptoms. Dr. Marta Di Forti, a professor at King’s College London, cautions, “For patients with a family history of psychosis, medical cannabis can exacerbate underlying conditions.”

The Medical Cannabis Clinicians Society emphasizes thorough assessments and ongoing monitoring as crucial components of safe prescribing practices. Singh acknowledges that while side effects are uncommon, the escalating use of high-THC products is concerning. “Rigorous monitoring and clinical oversight are absolutely essential,” he insists.

The evidence gap

The rising discord between patient experience and clinical evidence raises an uncomfortable yet critical discussion. “The current system for conducting clinical research has failed medical cannabis,” lamented Prof. David Nutt, founder of Drug Science. “The Department of Health has made promises about conducting efficacy trials, yet nothing has materialized.” The onus, it seems, lies not just with regulatory bodies but also with cannabis clinics to gather comprehensive data and assess patient outcomes systematically.

In the meantime, patients express fears of reverting to the illegal market where access to safe, medicinal cannabis would be non-existent. Dismissing medical cannabis based on incomplete evidence doesn’t just “misrepresent the science,” according to United Patients Alliance; it also jeopardizes the well-being of patients already navigating debilitating conditions.

The landscape of medical cannabis in the UK is fraught with complexities—from insufficient robust data to an urgent need for quality research. As the medical community grapples with evolving evidence and patient needs, the dialogue surrounding cannabis will continue to prompt critical questions, demanding responses that bridge the gap between anecdotal success and scientific rigor.

Source: www.sciencefocus.com