Causes Of Diarrhea - Diarrhea: Digestive Disorders

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Causes of diarrhea

Diarrhea may be caused by viruses, bacteria, or parasites, as well as by various foods, drugs, and medical conditions or treatments.

Viruses. A wide variety of viruses can cause diarrhea (viral gastroenteritis). Among them are rhinovirus or adenovirus, rotavirus (the most common cause of diarrhea in infants), influenza, and norovirus (the most common cause in adults). Most cases are not caused by viruses, although many of the most severe cases are.

Bacteria. A number of bacteria are associated with diarrhea. Shigella, V. cholerae, and E. coli produce toxins that cause diarrhea, while salmonella and campylobacter invade the stomach lining and produce inflammation and diarrhea. Food poisoning is usually due to bacterial contamination of food.

Parasites. Intestinal parasites, such as Giardia intestinalis, Cryptosporidium parvum, and roundworms or tapeworms, may cause diarrhea. These parasites are often found in untreated or contaminated water. Drinking untreated water from a lake or stream while camping is a common way to pick up giardia parasites.

Diseases of the bowel. Crohn's disease and ulcerative colitis, two forms of inflammatory bowel disease, can cause diarrhea (see "Irritable bowel syndrome: What else could it be?").

Immune deficiency. Patients suffering from diseases such as AIDS or those who are undergoing treatments that weaken the immune system, such as chemotherapy, may also suffer from severe diarrhea.

Stress. Emotions are known to wreak havoc on the bowels in a number of ways. Diarrhea is a common complaint of those under severe stress or emotional upset.

Foods. Certain foods, even if perfectly fresh, can cause diarrhea in some people. Among them are fruits, beans, and coffee. For most people, unripe fruits or any type of spoiled food will cause diarrhea, as will the particular foods that a person cannot tolerate, such as milk products for those who are lactose intolerant.

Medications. A number of drugs, available by prescription and over the counter, can cause diarrhea as a side effect. The worst culprits include antibiotics, antacids containing magnesium, and some blood pressure and heart medications. Because antibiotics kill some of the naturally occurring GI bacteria, the gut becomes more vulnerable to attack by Clostridium difficile, which can cause diarrhea.

Last updated:	August 21, 2007