The abnormal heart rhythms from atrial fibrillation (afib) can form clots that, in turn, trigger strokes. To prevent that, people with afib take a blood-thinning medication to prevent clotting. But also taking common over-the-counter painkillers can block clotting too much and lead to dangerous bleeding, according to a study in Annals of Internal Medicine.
Danish researchers examined health records of more than 150,000 people with afib. A third of them had also been prescribed nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen (Advil, Motrin) and naproxen (Aleve). These common pain relievers interfere with the body’s natural clotting function. Paradoxically, some NSAIDs have also been linked to higher risk of thromboembolism, or a clot that forms in the body and travel to the lungs, brain, or elsewhere.
The Danish study found that NSAIDs, when taken at the same time as blood thinners, caused two additional serious bleeding incidents for every 1,000 patients who took them for two weeks. “Serious” in this study means bleeding in the brain or gut. The study also confirmed a higher risk of thromboembolism.
People with afib who take blood thinners can avoid this small but potentially dangerous effect by taking acetaminophen—the non-NSAID pain reliever in Tylenol and many other brands. On the downside, acetaminophen doesn’t help with inflammation, and it can interfere with warfarin.
People with afib who take anticoagulants should avoid NSAIDs if they can, and if they do take them, use the lowest effective dose for the shortest period.