Diarrhea can be classified in several ways. It is both a symptom and a sign. As a symptom, it is whatever the patient says it is: a decrease in consistency, an increase in the number or volume of bowel movements, or any combination thereof. As a sign, diarrhea is an increase in stool weight (or volume) of more than 200 g (or ml) per 24 hours in a person on a Western diet. The distinction between chronic and acute diarrhea is arbitrary: it is determined by duration. Diarrhea is generally considered acute when it lasts less than two or three . . .