A new study revealed that taking blood thinners with common painkillers like ibuprofen or naproxen can double the risk of internal bleeding. Blood thinners are often prescribed to prevent strokes, heart attacks, or blood clots, while painkillers like NSAIDs also have a blood-thinning effect.

The study shows that combining the two can increase the risk of serious bleeding in areas like the gut, brain, lungs, and bladder. The study was published in the European Heart Journal.

Researcher and medical student Soren Riss Peterson from Aarhus University Hospital in Denmark said “We found that for patients taking blood thinners for blood clots in the legs or lungs, using NSAIDs doubled the risk of bleeding compared with not using NSAID." "The increased bleeding risk associated with NSAID use was not limited to the digestive tract but also seemed to affect other organ systems."

In a study of nearly 52,000 Danish patients who were prescribed blood thinners for blood clots between 2012 and 2022, researchers found that taking both a blood thinner and a painkiller (NSAID) like ibuprofen or naproxen doubled the risk of bleeding. In Denmark, painkillers like naproxen and diclofenac can only be bought with a prescription, so researchers could track patients who were prescribed both types of medicine.

The study showed that the bleeding risk was four times higher with naproxen, three times higher with diclofenac, and nearly twice as high with ibuprofen, compared to just taking a blood thinner alone. Apart from bleeding risk, using NSAIDs with blood thinners also triples a person’s risk of anemia.

This risk was similar across different blood thinners like rivaroxaban, apixaban, dabigatran, edoxaban, and warfarin. Petersen said in a journal release, "For people using blood thinners for blood clots in their legs or lungs, our study shows it's important to be careful when using NSAIDs for pain or inflammation."

"We advise patients to consult their doctor before taking NSAIDs with a blood thinner," said Dr Storey, a professor of clinical cardiology at the University of Sheffield. In an editorial, he added, "It's clear that avoiding NSAIDs with blood thinners is the safest way to reduce the risk of excessive bleeding.

However, if NSAIDs are necessary, they should be prescribed at the lowest dose for the shortest time. The type of NSAID and how it's taken may also be important."