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.


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 follow constipation, especially for people who have irritable bowel syndrome.

Diarrhea may also be caused by:

  • Infection by bacteria (the cause of most types of food poisoning)
  • Infections by other organisms, ie. Parasites, etc.
  • Eating foods that upset the digestive system
  • Allergies to certain foods
  • Medications
  • 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)
  • Hyperthyroidism
  • Some cancers
  • Laxative abuse
  • Alcohol abuse
  • Digestive tract surgery
  • Diabetes
  • Competitive running

Symptoms of diarrhea can be broken down into uncomplicated (non-serious) diarrhea and complicated (may be sign of more serious illness) diarrhea.

Symptoms of uncomplicated diarrhea typically include:

  • Abdominal bloating or cramps
  • Thin caliber 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 may include:

  • Blood, mucus, or undigested food in the stool
  • Weight loss
  • Fever

Contact your doctor if you have prolonged diarrhea, bloody 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.


Tests and procedures used to determine what's causing your diarrhea may include:

  • Physical exam.
  • Review of your medications (including supplements and over the counter drugs)
  • Blood tests
  • Stool test. Your doctor may recommend a stool test to determine whether a bacterium or parasite is causing your diarrhea.

Treatment is specific to the cause of diarrhea, as well as, the individual patient taking into consideration their overall health, medications, etc. If related to a viral illness, diarrhea typically lasts two to three days and can be treated with supportive measures and over-the-counter (OTC) medicines. If a specific bacterial or other infectious cause is found, sometimes antibiotics are needed. If a specific cause is not found and symptoms are persistent, a colonoscopy may be considered to evaluate for more unlikely causes to better determine the best course of treatment for you.