Pepto Bismol's active ingredient is bismuth subsalicylate, which treats diarrhea, heartburn, nausea, and indigestion.

Bismuth subsalicylate forms the core of Pepto Bismol, an over-the-counter medication widely used to relieve symptoms like diarrhea, heartburn, nausea, indigestion, and upset stomach. Its multiple actions make it effective against a variety of gastrointestinal complaints.