Diarrhea is an abnormality of bowel movements, characterized by loose, watery stool that is ejected at least three times in a 24-hour period. Bowel movements are accompanied by a heightened sense of urgency, which usually recurs frequently. There are many causes of diarrhea, including bacterial infections, the improper absorption or digestion of food, enzyme deficiencies, changes in diet or fluid intake, and irritable bowel syndrome. It also frequently occurs after air travel. While most cases of diarrhea resolve with little intervention, medical attention should be sought if it occurs in children, lasts for more than two days, is accompanied by weight loss, or if blood is present in the stool.