Taking Pepto-Bismol (bismuth subsalicylate) may help prevent the dreaded problem known as traveler's diarrhea. This common condition typically strikes during the first week of a trip to countries where the water and food are contaminated with bacteria, causing frequent watery stools and other gastrointestinal symptoms. According to the Centers for Disease Control and Prevention, taking bismuth subsalicylate can lower the risk for traveler's diarrhea. The recommended dose is two ounces of bismuth subsalicylate liquid or two tablets, taken four times daily. Check with your doctor for more information about using Pepto-Bismol to prevent traveler's diarrhea and to find out if it's safe for you to use this medicine.