The U.S. Food and Drug Administration issued a new warning about mixing drugs.
Patients should avoid using Prilosec with Plavix, officials said.
New data suggests when patients take both Prilosec for stomach acid and Plavix for anti-clotting, Plavix's ability to work may be reduced by half.
The drugs provide significant benefits, but patients at risk for heart attacks might not get the full effect of Plavix while taking Prilosec.
Plavix does not have anti-clotting effects without the help of liver enzymes, which can be blocked by prescription and over-the-counter Prilosec.
Studies showed similar results no matter what time of day the two drugs are taken, together or at different times, the FDA said in a news release today.
Patients who take Plavix and need acid relief need to talk with their doctors. Zantac, Pepcid, Axid and antacids do not inhibit the targeted liver enzyme and aren't expected to interfere with the anti-clotting activity of Plavix.
Plavix's manufacturers have agreed to continue studies to explore this and other drug interactions.