Diarrhea is the passage of frequent, more or less fluid stools. It is not a disease, but it is a sign of an
underlying disorder.
Diarrhea can be a reaction to certain foods, excessive alcohol consumption, cathartics, infections, or emotional problems. It may also be a symptom of a serious disease such as ulcerative colitis or cancer of the colon. Diarrhea is dangerous in infants because it can rapidly lead to dehydration.
The two basic mechanisms involved in diarrhea, which may operate independently or together, are excessive accumulation of fluid in the intestinal tract and excessive propulsive action in the
intestines. Excessive fluid in the intestines can result from
conditions that decrease the absorption of water from the colon, causing osmotic diarrhea, or from conditions that cause water to be secreted into the intestines, as in cholera and other infections. Excessive propulsive action may be caused by nervous and chemical factors or by partial obstruction of the intestine. Drugs may relieve distress in mild cases, but a physician should be consulted if severe diarrhea lasts more than two days, in order to address the underlying disorder.