Medical cannabis: Chronic pain management could lead to heart rhythm risk

Using medicinal cannabis to manage pain could lead to a slightly higher risk of developing an abnormal heart rhythm. Experts suggest improved monitoring should be in place for patients taking the drug, particularly those already at risk of cardiovascular disease.

According to Danish academics little research has been carried out on the side effects of medicinal cannabis - but recreational use of cannabis has been linked to heart issues. Their study included data from 5,391 patients in Denmark who had been prescribed cannabis for the first time between 2018 and 2021 for the likes of musculoskeletal, neurological and unspecified pain, as well as cancer.

In England, the use of cannabis products is not licensed to treat chronic pain, but you can get prescriptions for muscle stiffness and spasms caused by multiple sclerosis (MS), nausea associated with chemotherapy, and for some rare, severe forms of epilepsy.

The research team found patients using the drug had a 0.8% higher risk of being diagnosed with arrhythmia within 180 days of starting treatment. This was more than twice the risk of patients with chronic pain who were not taking medicinal cannabis, researchers said.

Arrhythmias, or heart rhythm problems, can cause the heart to beat irregularly, too fast, or too slow. The condition impacts about two million people in the UK, according to the NHS, although most can lead a normal life once properly diagnosed.

Dr Anders Holt, of Copenhagen University Hospital, led the study. He said: “I don’t think this research should make patients with chronic pain refrain from trying medical cannabis if other treatment has been inadequate. However, these results do suggest some improved monitoring may be advisable initially, especially in patients who are already at increased risk of cardiovascular disease.

“Despite our best efforts to make a balanced comparison, it can never be assumed that patients prescribed medical cannabis do not differ from patients not prescribed medical cannabis, and this could influence the results.”

Dr Holt added that “much more research” is needed in the area. “Before concluding anything, results from this study should be replicated in other countries and settings,” he said.

“It would also be interesting to understand if there are any links between long-term cannabis use and heart failure, stroke, or acute coronary syndrome. This would be an important area to clarify since chronic pain can persist for many years.”