Diclofenac is a non-steroidal anti-inflammatory drug (NSAID) that’s often used to treat arthritis and other painful joint conditions. In many countries, it’s available without a prescription.
Researchers found that the rate of first-time cardiovascular events was 20 to 30 percent higher among people who started taking diclofenac than among people who started taking ibuprofen or naproxen, which are also NSAIDs, or paracetamol (acetaminophen). These events included heart attacks, development of an irregular heart rhythm called atrial fibrillation, or death from heart problems.
The rate of new heart problems was 50 percent higher for diclofenac users than for people who weren’t taking any painkillers.
The researchers analyzed data from the Danish national patient registry. Altogether, they had information on nearly 1.4 million diclofenac users, 3.9 million ibuprofen users, 292,000 naproxen users, 765,00 paracetamol users, and 1.3 million people not on any of these painkillers.
“It is important to note that the absolute risk for the individual patient is low,” Morten Schmidt, lead author of the study, told Reuters Health in an email.
For example, among every 400 study participants taking diclofenac, roughly one person per year had a cardiovascular event, his team calculated.
Fewer people had cardiovascular events while taking other painkillers.
Schmidt and his coauthors say there is little reason to use diclofenac before trying other NSAIDs first. The drug should not be available over the counter, they say, and when prescribed, should be accompanied by appropriate warnings about its potential risks.
The increased risk was apparent even within 30 days of starting the drug and even with low doses, the researchers reported in The BMJ.
Schmidt said diclofenac was also associated with an increased gastrointestinal bleeding risk compared with ibuprofen.
“The real question is, do these different NSAIDs carry different risks… and the study showed that modestly diclofenac appears to be worse,” David Kaufman, Director of the Slone Epidemiology Center at Boston University, who was not involved with the study, told Reuters Health by phone.
Because it wasn’t a controlled experiment, the study can’t prove that diclofenac actually caused more cardiovascular events. Still, the authors say, their study included more people than most previous analyses and provides strong evidence to guide clinical decision making.
“It is time to acknowledge the potential health risk of diclofenac and to reduce its use,” the research team concludes.