There’s no definitive proof this combination is dangerous.

If a stent was inserted in your coronary arteries to improve blood flow, you may be taking clopidogrel (Plavix) and aspirin to prevent a blood clot from forming inside the stent. This combination of medications has been shown to reduce the risk of a fatal or nonfatal heart attack. As a result, clopidogrel has become one of most commonly prescribed medications in the United States.

However, both clopidogrel and aspirin can cause bleeding in the gastrointestinal (GI) tract. In people at increased risk of GI bleeding, this risk can be lowered by using proton-pump inhibitors (PPIs) to reduce the production of stomach acid. Millions of people with peptic ulcers and gastrointestinal reflux disease (GERD) also take these popular drugs, which include omeprazole (Prilosec), esomeprazole (Nexium), lansoprazole (Prevacid), dexlansoprazole (Dexilant, Kapidex), and pantoprazole (sold under many names).

When researchers found that omeprazole interfered with clopidogrel’s clot-fighting ability, the implications were enormous: millions of people who take both medications could be at increased risk for a heart attack or stroke. This left doctors unsure what to recommend.

Moving toward an answer

Recently, a study led by Harvard researchers found no evidence that concurrent use of clopidogrel and omeprazole causes an increase in heart attacks, strokes, or death. Dr. Deepak L. Bhatt, chief of cardiology at the VA Boston Health System and associate professor of medicine at Harvard Medical School, hopes this puts concerns to rest.

“In a test tube, there is a drug-drug interaction, but no randomized clinical trial has shown that it matters clinically,” he says. “PPIs like Prilosec may be taking the blame for a complex problem. Multiple factors affect the risk of a future cardiac event in patients with stents, including genetics, smoking, diabetes, being overweight, a heart attack versus stable coronary artery disease—and PPIs,” he explains.

If the drug-drug interaction were a major problem, doctors would expect to see blood clots in the stents of patients taking PPIs. But they don’t. “I would not tell a patient to stop taking PPIs. We see more problems when patients don’t fill their clopidogrel prescription,” says Dr. Bhatt.