Pepto Bismol didn't prevent travelers' diarrhea compared to placebo, small CDC study found

The active ingredient in Pepto Bismol, bismuth subsalicylate, is often used to treat and prevent diarrhea while traveling — but a new study found it may not help with prevention. 

In the study from the Centers for Disease Control and Prevention, "no significant difference" was found for symptoms of loose stool or diarrhea between groups who took the medication for prevention and those who took a placebo.  

Since 1939, bismuth subsalicylate has been approved by the Food and Drug Administration for the treatment of diarrhea, heartburn, indigestion, nausea and upset stomach. But, as the authors note, it's also used off-label for the prevention of diarrhea, especially among international travelers.