Experts make ‘weak’ recommendation of medical cannabis for chronic pain

A panel of experts have made a weak recommendation for a trial of non-inhaled medical cannabis for the treatment of chronic pain.

A new paper, published in the British Medical Journal earlier this month, concluded that non-inhaled cannabis showed a “small to very small” improvement in pain relief among chronic pain patients. 

The review, led by a panel of international experts made a weak recommendation for a trial of non-inhaled medical cannabis or cannabinoids for people living with chronic pain, if their standard care is not sufficient.

The recommendation is based on systematic reviews of 32 randomised trials exploring the benefits and harms of medical cannabis or cannabinoids for chronic pain, 39 observational studies exploring long-term harms, 17 studies of cannabis substitution for opioids, and 15 studies of patient values and preferences.

After reviewing this evidence, the panel was confident that non-inhaled medical cannabis or cannabinoids result in “small to very small improvements” in self-reported pain intensity, physical functioning, and sleep quality, but there was no improvement in emotional, role, or social functioning.

The panel also found no evidence linking psychosis to the use of medical cannabis or cannabinoids, but say they do carry a small to modest risk of mostly self limited and transient harms, such as loss of concentration, vomiting, drowsiness, and dizziness.

The study concluded: “Moderate to high certainty evidence shows that non-inhaled medical cannabis or cannabinoids results in a small to very small improvement in pain relief, physical functioning, and sleep quality among patients with chronic pain, along with several transient adverse side effects, compared with placebo.”

The subsequent recommendation applies to adults and children living with all types of moderate to severe chronic pain. 

However, it does not apply to smoked or vaporised forms of cannabis, recreational cannabis, or patients receiving end-of-life care.

The advice is part of The BMJ’s Rapid Recommendations initiative – to produce rapid and trustworthy guidelines for clinical practice based on new evidence to help doctors make better decisions with their patients.

The recommendation is weak because of the close balance between benefits and harms of medical cannabis for chronic pain. However, the panel issued strong support for shared decision making to ensure patients make choices that reflect their values and personal context.

It suggests further research should explore uncertainties such as optimal dose and formulation of therapy, and benefits and harms of inhaled medical cannabis, which may alter this recommendation.

Researchers welcome this new patient centred guidance, but say clinicians should emphasise the harms associated with vaping or smoking cannabis, discourage self medication, and pay particular attention to vulnerable populations.

They concluded: “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.”