A panel of international experts has made a ‘weak recommendation’ in The BMJ supporting a trial of non-inhaled medicinal cannabis for people living with chronic pain where standard care is insufficient.

The advice is part of The BMJ’s Rapid Recommendations initiative, aimed at producing fast and trustworthy guidelines for doctors based on new evidence.

It applies to adults and children living with all types of moderate to severe chronic pain, but excludes smoked or vaporised cannabis, recreational use, and patients receiving end-of-life care.

The BMJ explained ‘weak recommendations’ reflect the uncertainty in typical patients’ preferences, as well as the likely wide variability in preferences between patients.

In the case of medicinal cannabis, the panel’s recommendation was weak due to the close balance it found between benefits and harms as a treatment for chronic pain. However, it strongly favoured shared decision making to ensure patient choices reflect their values and personal context.

The findings follow a review of 32 randomised trials exploring the benefits and harms of medicinal cannabis or cannabinoids for chronic pain, 39 observational studies exploring long-term harms, 17 studies of cannabis substitution for opioids, and 15 surveys of patient values and preferences.

As a result, the panel was confident that non-inhaled medicinal cannabis or cannabinoids results in “small to very small improvements” in self-reported pain intensity, physical functioning, and sleep quality, and no improvement in emotional, role, or social functioning.

It found no evidence of a link between medicinal cannabis or cannabinoid use and psychosis, but identified a small to modest risk of mostly self limited and transient harms such as loss of concentration, vomiting, drowsiness, and dizziness.

The panel was unsure whether medicinal cannabis or cannabinoid use resulted in reduced opioid use, but found potential serious harms such as cannabis dependence, falls, suicidal ideation and suicide were uncommon, although it described the evidence as being of very low certainty.

It encouraged clinicians to emphasise the harms associated with vaping or smoking cannabis, discourage self medication, and pay particular attention to vulnerable populations.

“Increased pharmacovigilance of all cannabis use remains a priority, along with an ambitious programme of rigorous research on the short and long term effectiveness and safety of individual cannabis products for specific types of chronic pain,” the panel said.