In brief: On the basis of apparent risk/benefit ratios, the prophylactic use of antibiotics is not recommended for travelers to underdeveloped countries. When visiting certain high- risk areas such as Latin America, Southeast Asia, and Africa, travelers should obtain an antimotility drug or use bismuth subsalicylate for moderate forms of travelers' diarrhea. An antimicrobial agent such as doxycycline, trimethoprim, or trimethoprim-sulfamethoxazole is recommended for more severe travelers' diarrhea. Travelers who have persistent diarrhea with fever, serious fluid loss, or bloody stools should seek medical attention.