• Posted June 4, 2025

Pepto Bismol May Not Prevent Traveler’s Diarrhea, New Study Finds

Pepto Bismol is a go-to stomach remedy, but a new study suggests it might not help prevent diarrhea during international travel.

The study, led by the U.S. Centers for Disease Control and Prevention (CDC), found that people who took bismuth subsalicylate — the active ingredient in Pepto Bismol — did not have fewer episodes of diarrhea or loose stools than those who took a placebo, CBS News reported.

There was "no significant difference,” the researchers wrote May 29 in the Journal of Travel Medicine.

Pepto Bismol has been approved by the U.S. Food and Drug Administration (FDA) since 1939 to treat diarrhea, indigestion, heartburn, nausea and upset stomach. But many travelers take it off-label to try to prevent diarrhea during trips.

The study followed 270 adults who were planning to travel to parts of Southeast Asia, South Central Asia, North Africa or sub-Saharan Africa for one to three weeks.

The median age of the participants was 32 (meaning half were older, half younger). They were recruited from clinics in New York and Massachusetts.

One group took four tablets of bismuth subsalicylate twice a day while traveling. The other group took a placebo. Researchers collected data through questionnaires before, during and after the trip.

Even though the study didn’t reach its target number of participants, the findings still provide the first new data since the 1980s on preventive use of bismuth subsalicylate, the authors said.

The study suggests health care providers may want to rethink recommending Pepto Bismol for diarrhea prevention in travelers. Still, more research is needed.

"A larger study might show benefit, although the benefit may be small given the results of this study," said the reseachers, who were led by Dr. Kristina Angelo of the CDC's Division of Foodborne, Waterborne and Environmental Diseases. 

The medication used in the trial was provided by Procter & Gamble, maker of Pepto Bismol. 

However, the company did not take part in any part of the study, CBS News said.

More information

WebMD has more on the uses and side effects of Pepto-Bismol.

SOURCE: CBS News, June 3, 2025