Human Diseases and Conditions

Diarrhea describes loose, watery stools that occur more frequently than usual. Diarrhea is something everyone experiences. Diarrhea often means more frequent trips to the toilet and a greater volume of stool.
In most cases, diarrhea signs and symptoms usually last a couple of days. But sometimes diarrhea can last for weeks. In these situations, diarrhea can be a sign of a serious disorder, such as inflammatory bowel disease, or a less serious condition, such as irritable bowel syndrome.
Diarrhea may cause a loss of significant amounts of water and salts. Most cases of diarrhea go away without treatment. But see your doctor if diarrhea persists, if you become dehydrated or if you pass blood in your stool.

Signs and symptoms:

Signs and symptoms associated with diarrhea may include:

• Frequent, loose, watery stools
• Abdominal cramps
• Abdominal pain
• Fever
• Blood in the stool
• Bloating

Diarrhea occurs when the food and fluids you ingest pass too quickly or in too large an amount — or both — through your colon. Normally, your colon absorbs liquids from the food you eat, leaving a semisolid stool. But if the liquids from the foods you eat aren't absorbed, the result is a watery bowel movement.
A number of diseases and conditions can cause diarrhea. Common causes of diarrhea include:

• Viruses. Viruses that can cause diarrhea include Norwalk virus, cytomegalovirus and viral hepatitis. Rotavirus is a common cause of acute childhood diarrhea.
• Bacteria and parasites. Contaminated food or water can transmit bacteria and parasites to your body. Parasites such as Giardia lamblia and cryptosporidium can cause diarrhea. Common bacterial causes of diarrhea include campylobacter, salmonella, shigella and Escherichia coli. Diarrhea caused by bacteria and parasites can be common when traveling in developing countries, and is often called traveler's diarrhea.
• Medications. Many medications can cause diarrhea. The most common are antibiotics. Antibiotics destroy both good and bad bacteria, which can disturb the natural balance of bacteria in your intestines. This disturbance sometimes leads to an infection with bacteria called Clostridium difficile, which also can cause diarrhea.
• Lactose intolerance. Lactose is a sugar found in milk and other dairy products. Many people have difficulty digesting lactose and experience diarrhea after eating dairy products. Your body makes an enzyme that helps digest lactose, but for most people the levels of this enzyme drop off rapidly after childhood. This causes an increased risk of lactose intolerance as you age.
• Fructose. Fructose, a sugar found naturally in fruits and honey and added as a sweetener to some beverages, can cause diarrhea in people who have trouble digesting it.
• Artificial sweeteners. Sorbitol and mannitol, artificial sweeteners found in chewing gum and other sugar-free products, can cause diarrhea in some otherwise healthy people.
• Surgery. Some people may experience diarrhea after undergoing abdominal surgery or gallbladder removal surgery.
• Other digestive disorders. Chronic diarrhea has a number of other causes, such as Crohn's disease, ulcerative colitis, celiac disease, microscopic colitis and irritable bowel syndrome. 

How can dehydration be prevented and treated?

Oral rehydration solutions (ORS) are liquids that contain a carbohydrate (glucose or rice syrup) and electrolyte (sodium, potassium, chloride, and citrate or bicarbonate). Originally, the World Health Organization (WHO) developed the WHO-ORS to rapidly rehydrate victims of the severe diarrheal illness, cholera. The WHO-ORS solution contains glucose and electrolytes. The glucose in the solution is important because it forces the small intestine to quickly absorb the fluid and the electrolytes. The purpose of the electrolytes in the solution is the prevention and treatment of electrolyte deficiencies.
In the United States, convenient, premixed commercial ORS products that are similar to the WHO-ORS are available for rehydration and prevention of dehydration. Examples of these products are Pedialyte, Rehydralyte, Infalyte, and Resol.
Most of the commercially available ORS products in the U.S. contain glucose. Infalyte is the only one that contains rice carbohydrate instead of glucose. Most doctors believe that there are no important differences in effectiveness between glucose and rice carbohydrate.
Infants and young children. Most acute diarrhea in infants and young children is due to viral gastroenteritis and is usually short-lived. Antibiotics are not routinely prescribed for viral gastroenteritis. However, fever, vomiting, and loose stools can be symptoms of other childhood infections such as otitis media (infection of the middle ear), pneumonia, bladder infection, sepsis (bacterial infection in the blood) and meningitis. These illnesses may require early antibiotic treatment.
Infants with acute diarrhea also can quickly become severely dehydrated and therefore need early rehydration. For these reasons, sick infants with diarrhea should be evaluated by their pediatricians to identify and treat underlying infections as well as to provide instructions on the proper use of oral rehydration products.
Infants with moderate to severe dehydration usually are treated with intravenous fluids in the hospital. The pediatrician may decide to treat infants who are mildly dehydrated due to viral gastroenteritis at home with ORS.
Infants that are breast-fed or formula-fed should continue to receive breast milk during the rehydration phase of their illness if not prevented by vomiting. During, and for a short time after recovering from viral gastroenteritis, babies can be lactose intolerant due to a temporary deficiency of the enzyme, lactase (necessary to digest the lactose in milk) in the small intestine. Patients with lactose intolerance can develop worsening diarrhea and cramps when dairy products are introduced. Therefore, after rehydration with ORS, an undiluted lactose-free formula and diluted juices are recommended. Milk products can be gradually increased as the baby improves.
Older children and adults. During mild cases of diarrhea, diluted fruit juices, soft drinks containing sugar, sports drinks such as Gatorade, and water can be used to prevent dehydration. Caffeine and lactose containing dairy products should be temporarily avoided since they can aggravate diarrhea, the latter primarily in individuals with transient lactose intolerance. If there is no nausea and vomiting, solid foods should be continued. Foods that usually are well tolerated during a diarrheal illness include rice, cereal, bananas, potatoes, and lactose-free products.
ORS can be used for moderately severe diarrhea that is accompanied by dehydration in children older than 10 years of age and in adults. These solutions are given at 50 ml/kg over 4-6 hours for mild dehydration or 100 ml/kg over 6 hours for moderate dehydration. After rehydration, the ORS solution can be used to maintain hydration at 100 ml to 200 ml/kg over 24 hours until the diarrhea stops. Directions on the solution label usually state the amounts that are appropriate. After rehydration, older children and adults should resume solid food as soon as any nausea and vomiting subside. Solid food should begin with rice, cereal, bananas, potatoes, and lactose free and low fat products. The variety of foods can be expanded as the diarrhea subsides.

1. Schiller LR, et al. Diarrhea. In: Feldman M, et al. Sleisinger and Fordtran's Gastrointestinal and Liver Disease. 9th ed. Philadelphia, Pa.: Saunders; 2010. http://www.mdconsult.com/book/player/linkTo?type=bookHome&isbn=978-1-4160-6189-2&eid=4-u1.0-B978-1-4160-6189-2..X0001-7--TOP&uniq=200844987-3. Accessed May 12, 2010.
2. Diarrhea. National Institute of Diabetes and Digestive and Kidney Diseases. http://digestive.niddk.nih.gov/ddiseases/pubs/diarrhea. Accessed May 13, 2010.
3. Understanding food allergies and intolerances. American Gastroenterological Association. http://www.gastro.org/wmspage.cfm?parml=5679. Accessed May 14, 2010.
4. Surawicz CM, et al. Diarrheal diseases. American College of Gastroenterology. http://www.acg.gi.org/patients/gihealth/diarrheal.asp. Accessed May 13, 2010.
5. Nutrition therapy for diarrhea. ADA Nutrition Care Manual. http://nutritioncaremanual.org/index.cfm. Accessed May 13, 2010.