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 medicines. Others have diarrhea often 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 into the bowel. A common example of this is "dietetic candy" or "chewing gum" diarrhea, in which a sugar substitute, such as sorbitol, is not absorbed by the body but draws water from the body into the bowel, resulting in diarrhea.

Secretory diarrhea occurs when the body is releasing water into the bowel when it's not supposed to. 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.

What Causes Diarrhea?
The most common cause of diarrhea is a virus that infects the gut. The infection usually lasts for two days and is sometimes called "intestinal flu" or "stomach flu." Diarrhea may also be caused by:

Infection by bacteria (the cause of most types of food poisoning)
Infections by other organisms
Eating foods that upset the digestive system
Allergies to certain foods
Radiation therapy
Diseases of the intestines (Crohn's disease, ulcerative colitis)
Malabsorption (where the body is unable to adequately absorb certain nutrients from the diet)
Some cancers
Laxative abuse
Alcohol abuse
Digestive tract surgery
Competitive running
Diarrhea may also follow constipation, especially for people who have irritable bowel syndrome.

What Are the Symptoms of Diarrhea?
Symptoms of diarrhea can be broken down into uncomplicated (or non-serious) diarrhea and complicated diarrhea. Complicated diarrhea may be a sign of a more serious illness.

Symptoms of uncomplicated diarrhea include:

Abdominal bloating or cramps
Thin or loose stools
Watery stool
Sense of urgency to have a bowel movement
Nausea and vomiting
In addition to the symptoms described above, the symptoms of complicated diarrhea include:

Blood, mucus, or undigested food in the stool
Weight loss
Contact your doctor if you have prolonged diarrhea or a fever that lasts more than 24 hours. Also see your doctor promptly if vomiting prevents you from drinking liquids to replace lost fluids.

How Is Diarrhea Treated?
If you have a mild case of diarrhea, you can just let it run its course, or you can treat it with an over-the-counter medicine. Common brand names include Pepto-Bismol, Imodium A-D, and Kaopectate, which are available as liquids or tablets. Follow the instructions on the package.

In addition, you should drink at least six 8-ounce glasses of fluid per day. Choose fruit juice without pulp, broth, or soda (without caffeine). Chicken broth (without the fat), tea with honey, and sports drinks are also good choices. Instead of drinking liquids with your meals, drink liquids between meals. Drink small amounts of fluids frequently.

How Can I Relieve Discomfort in the Rectal Area?
If your rectal area becomes sore because of frequent bowel movements, or if you experience itching, burning, or pain during bowel movements:

Try warm baths. Afterwards, pat the area dry (do not rub) with a clean, soft towel.
Apply a hemorrhoid cream or white petroleum jelly to the anus.

Can Diarrhea Harm My Health?
Yes. Ongoing diarrhea causes the body to lose large amounts of water and nutrients. If you have watery stools more than three times a day and you are not drinking enough fluids, you could become dehydrated, which can cause serious complications if not treated.

Notify your doctor if you have ongoing diarrhea and are experiencing any of the following signs of dehydration:

Dark urine
Small amount of urine
Rapid heart rate
Dry skin
Signs of dehydration in young children include:

Dry mouth and tongue
Sunken eyes or cheeks
No or decreased tear production
Decreased number of wet diapers
Irritability or listlessness
Skin that stays pinched instead of flattening out after being pinched
When Should I Call My Doctor About Diarrhea?
Some cases of diarrhea require medical attention. Diarrhea can quickly deplete the body's supply of water and electrolytes (such as sodium and potassium) that tissues need to function. People who are very young, old, or sick may have difficulty replacing lost fluids. Also, when diarrhea lasts for several weeks or contains blood, a serious illness may be the cause. In these cases, you should contact your doctor immediately.