Health regulators said ulcer drugs such as AstraZeneca Plc's blockbuster Nexium could increase the risk of clostridium difficile-associated diarrhea (CDAD).
Clostridium difficile is a bacterium that can cause colitis and other intestinal conditions.
The U.S. Food and Drug Administration said patients who develop diarrhea after taking these drugs should be checked for CDAD.
The drugs called proton pump inhibitors (PPIs) are widely used for treating ulcers, acid reflux and other conditions.
Other PPIs sold by prescription include Takeda Pharmaceutical Co Ltd's Dexilant and Prevacid, AstraZeneca's Prilosec and Vimovo, Santarus Inc's Zegerid, and Johnson & Johnson and Eisai Co Ltd's AcipHex.
Generic versions of Prevacid and Prilosec also are available.
Details were released on the FDA website at link.reuters.com/wag56s