Diarrhea is the frequent passage of unusually soft, damp stools. It is usually caused by an intestinal bacterial infection or by certain medical conditions. Prolonged diarrhea can deplete fluids, salts, and nutrients and should be treated by a physician. If your baby has diarrhea, see a physician without delay.

The active ingredients found in most OTC antidiarrheal medicines are either antiperistaltic or adsorbent.

Antiperistaltic medicines decrease the propulsive force of the intestines and thus make the fecal matter move through the bowels at a slower rate. Loperamide is the active ingredient to look for in OTC antiperistaltic diarrhea medicine.

Attapulgite is the active ingredient found in most adsorbent antidiarrheal medicines. It binds with irritants in the bowel and also absorbs water into the bowel. This produces larger, less frequent stools. Adsorbent antidiarrheal medicines are gentler than antiperistaltic medicines.

Bismuth subsalicylate (Pepto Bismol)is the active ingredient used in preparations thought to be effective in preventing and treating travelers' diarrhea. It creates a beneficial effect by inhibiting intestinal secretions.

Oral rehydration therapy may be necessary if prolonged diarrhea has caused dehydration. Products such as Kao Lectrolyte and Pedialyte help restore several of the body's chemicals lost through vomiting and diarrhea.