– A change in bowel habits marked by frequent passage of loose, watery, unformed stool. Diarrhea may be an acute or a chronic condition.

Causes and Incidence

Diarrhea can be caused by a wide range of factors, such as sugar intolerance, use of antacids that contain poorly absorbed salts, laxative abuse, ingestion of large amounts of certain sugar substitutes, bacterial toxins, viral infections, bile acids, drugs, fat or carbohydrate malabsorption syndromes, mucosal disease, and bowel surgery that alters intestinal transit and strictures. Diarrhea is a common symptom that may be transient or may indicate underlying disease.

Disease Process

Diarrhea occurs when the amount of fluid absorbed by the body declines; when the amount of fluid produced increases, overwhelming the bowel’s absorptive capacities; when motor disturbances affect bowel motility and secretory capacities; or when injury to the bowel mucosa produces blood and mucus in the stool.


The primary symptom is a change in normal bowel habits that results in frequent, loose, watery, unformed stools that are often accompanied by cramping, abdominal pain, and urgency.

Potential Complications

Hypokalemia, dehydration, and vascular collapse are possible complications with severe or chronic diarrhea. Infants and small children are particularly prone to dehydration.

Diagnostic Tests

The diagnosis is made by clinical evaluation, history, and examination of the stool macroscopically and microscopically. Stool measurements, cultures, microscopic examination, and flexible sigmoidoscopy can help determine the cause.



Antidiarrheal drugs that increase intestinal tone (i.e., paregoric), reduce peristalsis (anticholinergics), increase bulk (methylcellulose), and absorb fluid (pectin).

Treatment of underlying disorder; monitoring and replacement of fluid and electrolytes; perirectal skin care.