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What Is Diarrhea?

Part 1 - Causes and symptoms of diarrhea.

By National Digestive Diseases Information Clearinghouse

Updated June 12, 2014

What is diarrhea?

Diarrhea--loose, watery stools occurring more than three times in one day--is a common problem that usually lasts a day or two and goes away on its own without any special treatment. However, prolonged diarrhea can be a sign of other problems.

Diarrhea can cause dehydration, which means the body lacks enough fluid to function properly. Dehydration is particularly dangerous in children and the elderly, and it must be treated promptly to avoid serious health problems. Dehydration is discussed below.

People of all ages can get diarrhea. The average adult has a bout of diarrhea about four times a year.

What causes diarrhea?

Diarrhea may be caused by a temporary problem, like an infection, or a chronic problem, like an intestinal disease. A few of the more common causes of diarrhea are:

  • Bacterial infections. Several types of bacteria, consumed through contaminated food or water, can cause diarrhea. Common culprits include Campylobacter, Salmonella, Shigella, and Escherichia coli.
  • Viral infections. Many viruses cause diarrhea, including rotavirus, Norwalk virus, cytomegalovirus, herpes simplex virus, and viral hepatitis.
  • Food intolerances. Some people are unable to digest a component of food, such as lactose, the sugar found in milk.
  • Parasites. Parasites can enter the body through food or water and settle in the digestive system. Parasites that cause diarrhea include Giardia lamblia, Entamoeba histolytica, and Cryptosporidium.
  • Reaction to medicines, such as antibiotics, blood pressure medications, and antacids containing magnesium.
  • Intestinal diseases, like inflammatory bowel disease or celiac disease.
  • Functional bowel disorders, such as irritable bowel syndrome, in which the intestines do not work normally.

Some people develop diarrhea after stomach surgery or removal of the gallbladder. The reason may be a change in how quickly food moves through the digestive system after stomach surgery or an increase in bile in the colon that can occur after gallbladder surgery.

In many cases, the cause of diarrhea cannot be found. As long as diarrhea goes away on its own, an extensive search for the cause is not usually necessary.

People who visit foreign countries are at risk for traveler's diarrhea, which is caused by eating food or drinking water contaminated with bacteria, viruses, or, sometimes, parasites. Traveler's diarrhea is a particular problem for people visiting developing countries. Visitors to the United States, Canada, most European countries, Japan, Australia, and New Zealand do not face much risk for traveler's diarrhea.

What are the symptoms of diarrhea?

Diarrhea may be accompanied by cramping abdominal pain, bloating, nausea, or an urgent need to use the bathroom. Depending on the cause, a person may have a fever or bloody stools.

Diarrhea can be either acute or chronic. The acute form, which lasts less than 3 weeks, is usually related to a bacterial, viral, or parasitic infection. Chronic diarrhea lasts more than 3 weeks and is usually related to functional disorders like irritable bowel syndrome or diseases like celiac disease or inflammatory bowel disease.

Diarrhea in children

Children can have acute (short-term) or chronic (long-term) forms of diarrhea. Causes include bacteria, viruses, parasites, medications, functional disorders, and food sensitivities. Infection with the rotavirus is the most common cause of acute childhood diarrhea. Rotavirus diarrhea usually resolves in 5 to 8 days.

Medications to treat diarrhea in adults can be dangerous to children and should be given only under a doctor's guidance.

Diarrhea can be dangerous in newborns and infants. In small children, severe diarrhea lasting just a day or two can lead to dehydration. Because a child can die from dehydration within a few days, the main treatment for diarrhea in children is rehydration. Rehydration is discussed on the next page.

Take your child to the doctor if any of the following symptoms appear:

  • Stools containing blood or pus, or black stools.
  • Temperature above 101.4 degrees Fahrenheit.
  • No improvement after 24 hours.
  • Signs of dehydration (see below).
What is dehydration? General signs of dehydration include:
  • Thirst.
  • Less frequent urination.
  • Dry skin.
  • Fatigue.
  • Light-headedness.

Signs of dehydration in children include:

  • Dry mouth and tongue.
  • No tears when crying.
  • No wet diapers for 3 hours or more.
  • Sunken abdomen, eyes, or cheeks.
  • High fever.
  • Listlessness or irritability.
  • Skin that does not flatten when pinched and released.

If you suspect that you or your child is dehydrated, call the doctor immediately. Severe dehydration may require hospitalization.

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