People living with persistent chronic cancer or non-cancer pain should be offered a trial of non-inhaled medical cannabis on top of standard care to improve pain control, according to new advice by a panel of international experts.

However, the strength of the recommendation is “weak” as there was a close balance between the potential benefits and harms of medical cannabis in the treatment of chronic pain, conclude authors of the guideline, which is part of the BMJ’s Rapid Recommendations for clinical practice initiative.

The authors said the recommendation applied to “adults and children living with moderate to severe chronic pain regardless of pain mechanism – neuropathic pain (resulting from injury to the somatosensory nervous system, such as diabetic neuropathy); nociceptive pain (injury to non-neural tissues producing noxious stimulus, such as osteoarthritis); and nociplastic pain (pain arising from altered nociception despite no clear evidence of tissue damage, such as fibromyalgia).”

A review, led by Dr Jason Busse, from the Michael G DeGroote Centre for Medicinal Cannabis Research at McMaster University in Hamilton, Canada uncovered no evidence of a link between psychosis and the use of medical cannabis/cannabinoids, but there was a small to modest risk of mostly self limited and transient harms, including loss of concentration, vomiting, drowsiness and dizziness.

Also, while potential serious harms such as cannabis dependence, falls, suicidal ideation or suicide were uncommon, the evidence was only very low certainty, the panel noted.

On the plus side, use of medical cannabis/cannabinoids was found to result in a small increase in the proportion of people who experienced an important improvement in pain and sleep quality, with the evidence considered to be of high and moderate certainty, respectively.

In a linked editorial published in the British Medical Journal, another groups of Canadian researchers stressed that clinicians should emphasise to patients the harms linked with vaping or smoking cannabis and suggest use of products with known compositions as recommended by other guidelines, such as nabilone or nabiximols. They should also “discourage self medication, and pay particular attention to vulnerable populations”.