Information about Loose, Watery Stools

Diarrhea is a common health problem that causes loose, watery stools. Acute diarrhea lasts for no more than two weeks. However, diarrhea that lasts longer than two months is considered a chronic condition.

Causes of diarrhea

Acute diarrhea is usually caused by an infectious agent. Most organisms causing diarrhea originate in feces and enter the mouth via the hands or contaminated food or water. Acute infectious diarrhea can be caused by a wide variety of bacteria, viruses, and parasites. Bacteria implicated in acute diarrhea include Salmonella, Shigella, Campylobacter jejuni, Escherichia coli O157:H7, and Clostridium difficile. Viral causes include adenoviruses, rotaviruses, and the Norwalk-like viruses known as the Noroviruses; parasites include Entamoeba histolytica, Giardia lamblia, and Cryptosporidium.

Chronic diarrhea can be classified into three types: osmotic, secretory, and inflammatory. Osmotic diarrhea is caused by ingestion of poorly absorbed substances (such as magnesium or aluminum salts in oral laxatives) or by incomplete digestion and malabsorption of food components such as lactose and sorbitol.

Secretory diarrhea usually results in large amounts of watery stools. This type of diarrhea is caused by production and secretion of excessive fluid by the small intestine, usually the result of a rare, cancerous neuroendocrine tumor occurring in the digestive tract. The tumors release hormones into the bloodstream that stimulate the small intestine to secrete excessive amounts of fluid and electrolytes such as sodium and potassium. Cholera outbreaks in developing countries may cause secretory diarrhea.

Inflammatory diarrhea produces bloody, watery stools. It occurs when inflammation in the lining of the colon increases stool volume by decreasing the absorption of water from the stool. This type of diarrhea is common in people with Crohn's disease and ulcerative colitis, the two main types of inflammatory bowel disease. Diarrhea, as well as constipation, is also a hallmark of irritable bowel syndrome.

Symptoms of diarrhea

The main symptom of diarrhea is an increased number of bowel movements along with a decreased consistency of the stools, which may be semi-solid or watery. Other symptoms of diarrhea include feelings of urgency and abdominal discomfort and pain.

Diagnosis of diarrhea

Most cases of acute diarrhea do not require a call to your doctor. However, if diarrhea persists for 48 hours or more, is severe (more than six stools per day), or is accompanied by fever, severe abdominal pain, or blood in the stool, you should see a doctor. You may be asked to give a stool sample to identify the infectious agent causing the diarrhea.

Diagnosing chronic diarrhea is more involved. It requires a detailed evaluation that includes an upper endoscopy and/or a colonoscopy with a biopsy to rule out infections or inflammation.

Treatment of diarrhea

Most of the time, a bout of acute diarrhea requires no treatment beyond rest and drinking plenty of fluids to prevent dehydration until the symptoms subside on their own. Medications to control acute diarrhea are not recommended; you should allow the illness to run its course. However, if the diarrhea is causing you much inconvenience, you can take an anti-diarrheal product such as bismuth subsalicylate (Pepto-Bismol, Kaopectate, and other brands) or kaolin/pectin (Kao-Spen, Kapectolin) to solidify the stool. Other antidiarrheal medications, such as loperamide (Imodium A-D) or diphenoxylate/atropine (Lomotil), also are helpful because they slow the movement of the GI tract.

Intravenous fluid administration in the hospital is required in some cases of severe diarrhea. Certain cases of infectious diarrhea, particularly those caused by bacteria like Salmonella typhi and E. coli O157:H7, can be serious. Antibiotics to eradicate the organism are usually recommended if symptoms have not improved after 48 hours of treatment with fluids and an antidiarrheal product. The antibiotics most frequently used to treat diarrhea caused by bacteria are ciprofloxacin (Cipro) and trimethoprim plus sulfamethoxazole (Bactrim).

Cases of acute diarrhea caused by a parasite are often treated with metronidazole (Flagyl). Antibiotics are most effective when started in the first three days of the illness.

Treatment of osmotic diarrhea involves avoiding foods, drinks, or medications that cause the condition. For example, stimulant laxatives such as Correctol or Dulcolax should not be used, and people should limit their use of chewing gum and foods that contain the artificial sweetener sorbitol. If the pancreas produces insufficient digestive enzymes to break down fats, supplemental digestive enzymes can be taken with meals.

Treatment of secretory diarrhea caused by a neuroendocrine tumor requires locating and removing the tumor.

Treatment of inflammatory diarrhea involves treating the underlying inflammatory bowel disease.

Publication Review By: H. Franklin Herlong, M.D.

Published: 25 Mar 2011

Last Modified: 02 Dec 2014