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.

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 – most often bacteria consumed through contaminated food or water
  • viral infections – many viruses cause diarrhea, including rotavirus, norovirus, cytomegalovirus, herpes and viral hepatitis
  • parasites – can enter the body through food or water and settle in the digestive system
  • functional bowel disorders – diarrhea can be a symptom
  • intestinal disease – inflammatory bowel disease, ulcerative colitis, Crohn’s disease, and celiac disease often lead to diarrhea
  • food intolerance and sensitivities
  • reaction to medicines

In many cases, the cause of diarrhea cannot be found. As long as diarrhea goes away on its own within 1 to 2 days and finding the cause may not be necessary.

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. Diarrhea can cause dehydration and is particularly dangerous in children, older adults, and people with weakened immune systems. Dehydration can cause serious problems such as organ damage, shock, or even a coma.Symptoms of dehydration may include:

  • thirst
  • less frequent urination than usual
  • dark-colored urine
  • dry skin
  • fatigue
  • dizziness
  • light-headedness

Signs of dehydration in children and infants 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

When people are dehydrated, their skin does not return back to normal right away after being pinched.

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 board certified physician may be needed to perform tests to determine the cause.Diagnostic tests to find the cause of diarrhea may include the following:

  • review of medical history and a physical examination
  • stool culture to be examined for bacteria, parasites, or other signs of diseases
  • blood tests for ruling out certain diseases
  • fasting tests to determine if food allergy or intolerance is the cause
  • colonoscopy to look for signs of intestinal diseases that cause diarrhea