A new Israeli study reveals that Celebrex and other anti-inflammatory coxib medications may counter the positive effects of aspirin in preventing blood clots.

The research, conducted at Ben-Gurion University of the Negev (BGU), indicates that people who are taking aspirin and coxibs together are in fact inhibiting the aspirin’s effectiveness in preventing heart attacks and strokes.

“This finding strongly suggests that humans who are consuming coxibs and a low dose of aspirin simultaneously are exposed to a greater risk of cardiovascular events,” said Professor Gilad Rimon, of BGU’s Department of Clinical Pharmacology.

About 50 million Americans take aspirin every day to reduce their risk of cardiovascular diseases. Aspirin is the oldest and one of the most effective non-steroidal anti-inflammatory drugs. It is also well known for its ability to prevent the blood clots that can potentially lead to heart attack and stroke.

In the past decade, a new group of anti-inflammatory drugs, coxibs, which include Celebrex and Arcoxia was developed to treat arthritis as well as other pain. Arthritis patients who take Celebrex are instructed to take low-dose aspirin to counteract Celebrex’s own potential clot-promoting effect.

Now, the BGU research suggests that in the presence of coxibs, aspirin’s protective role in preventing new blood clots is blunted.