Chronic diarrhea unresponsive to conventional medication: Are you taking lansoprazole?

Lansoprazole is a proton pump inhibitor which powerfully suppresses gastric acid production and is widely prescribed for chronic use in gastroesophageal reflux disease. Lansoprazole uncommonly causes chronic watery diarrhea unresponsive to conventional medication as a symptom of collagenous colitis. This association has recently been reported and is not widely known. Correct diagnosis and treatment without this knowledge is impossible. Discontinuation of lansoprazole results in the prompt resolution of diarrhea.