Diarrhea describes bowel movements (stools) that are loose and watery. It is very common and usually not serious. Many people will have diarrhea once or twice each year. It typically lasts two to three days and can be treated with over-the-counter (OTC) medicines. Some people often have diarrhea as part of irritable bowel syndrome or other chronic diseases of the large intestine.
Doctors classify diarrhea as "osmotic," "secretory," or "exudative."
Osmotic diarrhea means that something in the bowel is drawing water from the body. A common example is sorbitol, a sugar substitute found in sugarless candy and gum that isn't absorbed by the body but draws water into the bowel, resulting in diarrhea.
Secretory diarrhea occurs when the body is releasing water into the bowel. Many infections, drugs, and other conditions cause secretory diarrhea.
Exudative diarrhea refers to the presence of blood and pus in the stool. This occurs with inflammatory bowel diseases such as Crohn's disease or ulcerative colitis, and several infections.