A new study from Gentofte University Hospital in Denmark has found that people using medical marijuana to treat chronic pain may have a small but increased risk of developing heart rhythm problems, also known as arrhythmias.
The study looked at medical records from a large national database, including 1.6 million patients with chronic pain. These patients had a variety of health issues, such as cancer, arthritis, or neurological conditions. Out of all of them, nearly 4,600 people had filled at least one prescription for medical cannabis.
The researchers found that people who used medical marijuana were 64% more likely to experience a heart arrhythmia within six months of starting the treatment compared to those who did not use the drug.
While that number sounds high, the absolute risk was still small. About 0.9% of patients on medical marijuana developed an arrhythmia, compared to 0.5% of those who didn’t use it.
In Denmark, medical marijuana comes in a few different forms, all of which are taken by mouth. These include CBD-based oral solutions and sprays, teas that contain both THC and CBD, and a synthetic version of THC called dronabinol. The study found that the increased risk applied to all types of medical cannabis used.
It’s important to note that many of the people using medical marijuana were also dealing with severe pain, which might have played a role in the results. For example, people with more intense pain may also be more likely to use opioids, which themselves can affect heart rhythm. So, it’s hard to say for sure whether the marijuana alone caused the increased risk.
The researchers also pointed out that arrhythmias can range from mild to serious, and the study did not focus on specific types. However, it is well known that chemicals in cannabis—especially THC—can influence the heart and blood vessels.
They can raise heart rate, change blood pressure, and may even increase the risk of blood clots in some people. These effects could explain why cannabis might impact heart rhythm.
While this study doesn’t prove that medical marijuana directly causes heart problems, it does suggest that people using it—especially those with existing heart issues—should talk to their doctor and be aware of potential risks. The findings were presented by Dr. Nina Nouhravesh and her team at a meeting of the European Society of Cardiology.
As medical marijuana becomes more widely used for pain and other conditions, researchers say it’s important to continue studying its long-term effects on heart health. For now, the message is clear: medical marijuana can help with chronic pain, but like all medicines, it may come with some risks.
If you care about heart health, please read studies about top 10 foods for a healthy heart, and how to eat right for heart rhythm disorders.
For more health information, please see recent studies about how to eat your way to cleaner arteries, and salt and heart health: does less really mean more?
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