What is diarrhea?
Diarrhea is loose, watery stools. Having diarrhea means passing loose stools three or more times a day. Acute diarrhea is a common problem that usually lasts 1 or 2 days and goes away on its own.
Diarrhea lasting more than 2 days may be a sign of a more serious problem. Chronic diarrhea—diarrhea that lasts at least 4 weeks—may be a symptom of a chronic disease. Chronic diarrhea symptoms may be continual or they may come and go.
Diarrhea of any duration may cause dehydration, which means the body lacks enough fluid and electrolytes—chemicals in salts, including sodium, potassium, and chloride—to function properly. Loose stools contain more fluid and electrolytes and weigh more than solid stools.
People of all ages can get diarrhea. In the United States, adults average one bout of acute diarrhea each year,1 and young children have an average of two episodes of acute diarrhea each year.
What causes diarrhea?
Acute diarrhea is usually caused by a bacterial, viral, or parasitic infection. Chronic diarrhea is usually related to a functional disorder such as irritable bowel syndrome or an intestinal disease such as Crohn’s disease.
The most common causes of diarrhea include the following:
- Bacterial infections. Several types of bacteria consumed through contaminated food or water can cause diarrhea. Common culprits include Campylobacter, Salmonella, Shigella, and Escherichia coli (E. coli).
- Viral infections. Many viruses cause diarrhea, including rotavirus, norovirus, cytomegalovirus, herpes simplex virus, and viral hepatitis. Infection with the rotavirus is the most common cause of acute diarrhea in children. Rotavirus diarrhea usually resolves in 3 to 7 days but can cause problems digesting lactose for up to a month or longer.
- 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.
- Functional bowel disorders. Diarrhea can be a symptom of irritable bowel syndrome.
- Intestinal diseases. Inflammatory bowel disease, ulcerative colitis, Crohn’s disease, and celiac disease often lead to diarrhea.
- Food intolerances and sensitivities. Some people have difficulty digesting certain ingredients, such as lactose, the sugar found in milk and milk products. Some people may have diarrhea if they eat certain types of sugar substitutes in excessive quantities.
- Reaction to medicines. Antibiotics, cancer drugs, and antacids containing magnesium can all cause diarrhea.
Some people develop diarrhea after stomach surgery, which may cause food to move through the digestive system more quickly.
People who visit certain foreign countries are at risk for traveler’s diarrhea, which is caused by eating food or drinking water contaminated with bacteria, viruses, or parasites. Traveler’s diarrhea can be a problem for people traveling to developing countries in Africa, Asia, Latin America, and the Caribbean. Visitors to Canada, most European countries, Japan, Australia, and New Zealand do not face much risk for traveler’s diarrhea.
In many cases, the cause of diarrhea cannot be found. As long as diarrhea goes away on its own within 1 to 2 days, finding the cause is not usually necessary.
What other symptoms accompany diarrhea?
Diarrhea may be accompanied by cramping, abdominal pain, nausea, an urgent need to use the bathroom, or loss of bowel control. Some infections that cause diarrhea can also cause a fever and chills or bloody stools.
Dehydration
Diarrhea can cause dehydration. Loss of electrolytes through dehydration affects the amount of water in the body, muscle activity, and other important functions.
Dehydration is particularly dangerous in children, older adults, and people with weakened immune systems. Dehydration must be treated promptly to avoid serious health problems, such as organ damage, shock, or coma—a sleeplike state in which a person is not conscious.
Signs of dehydration in adults include
- thirst
- less frequent urination than usual
- dark-colored urine
- dry skin
- fatigue
- dizziness
- light-headedness
Signs of dehydration in infants and young children include
- dry mouth and tongue
- no tears when crying
- no wet diapers for 3 hours or more
- sunken eyes, cheeks, or soft spot in the skull
- high fever
- listlessness or irritability
Also, when people are dehydrated, their skin does not flatten back to normal right away after being gently pinched and released.
Anyone with signs of dehydration should see a health care provider immediately. Severe dehydration may require hospitalization.
Although drinking plenty of water is important in preventing dehydration, water does not contain electrolytes. Adults can prevent dehydration by also drinking liquids that contain electrolytes, such as fruit juices, sports drinks, caffeine-free soft drinks, and broths. Children with diarrhea should be given oral rehydration solutions such as Pedialyte, Naturalyte, Infalyte, and CeraLyte to prevent dehydration.
How is the cause of diarrhea diagnosed?
If acute diarrhea lasts 2 days or less, diagnostic tests are usually not necessary. If diarrhea lasts longer or is accompanied by symptoms such as fever or bloody stools, a doctor may perform tests to determine the cause.
Diagnostic tests to find the cause of diarrhea may include the following:
- Medical history and physical examination. The doctor will ask about eating habits and medication use and will perform a physical examination to look for signs of illness.
- Stool culture. A sample of stool is analyzed in a laboratory to check for bacteria, parasites, or other signs of disease and infection.
- Blood tests. Blood tests can be helpful in ruling out certain diseases.
- Fasting tests. To find out if a food intolerance or allergy is causing the diarrhea, the doctor may ask a person to avoid foods with lactose, carbohydrates, wheat, or other ingredients to see whether the diarrhea responds to a change in diet.
- Sigmoidoscopy or colonoscopy. These tests may be used to look for signs of intestinal diseases that cause chronic diarrhea. For sigmoidoscopy, the doctor uses a thin, flexible, lighted tube with a lens on the end to look at the inside of the rectum and lower part of the colon. Colonoscopy is similar to sigmoidoscopy, but it allows the doctor to view the entire colon.
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