Encyclopedia / D / Diarrhea


What Is Diarrhea?

Acute diarrhea—the passage of frequent, loose, or watery stools—is not a disease itself but rather a symptom of an underlying disorder.

As food passes through the digestive system, its water content is normally absorbed through the wall of the large intestine. Diarrhea—and, at times, dehydration—results when fluid is not absorbed but remains in and is expelled with the fecal matter.

Although diarrhea usually subsides without treatment within two or three days, resulting dehydration can be serious and often requires prompt treatment.

Who Gets Diarrhea?

In more than 90 percent of cases, acute diarrhea is caused by infectious agents (e.g., viruses, bacteria, parasites) that are ingested in food and water. Infectious diarrhea also may be accompanied by abdominal pain, vomiting, and fever.

Acute diarrhea usually is mild and resolves on its own in one or two days. However, the condition can be serious, especially in infants and young children, the elderly, and patients with a compromised immune system (e.g., patients who have HIV/AIDS).


  • Loose, watery stools.
  • Increased frequency of bowel movements.
  • Abdominal cramping and pain.
  • Excessive gas.
  • Dehydration, which is more common in young children and in the elderly. Signs include the following:
    • Dark-colored urine.

    • Dry skin.

    • Excessive thirst.

    • Fever above 102° F.

    • Decrease urine output.

Emergency symptoms of dehydration in infants:

  • Slackness of the skin.
  • Glazed eyes.
  • Dry, sticky mouth and tongue.
  • Persistent crying.

Causes/Risk Factors

  • Food poisoning from various infectious agents, including viruses or bacteria.
  • Non-food-related viral infections.
  • Reaction to certain foods (such as citrus fruits or beans).
  • Intolerance to foods, such as lactose (sugar present in milk) and gluten (protein in wheat).
  • Large amounts of artificial sweeteners, such as sorbitol, xylitol, and mannitol, which are found in diet foods, chewing gum, and other products.
  • Alcoholic beverages.
  • Some drugs including antihypertensive medications to treat high blood pressure and combat heart disease, over-the-counter (OTC) antacids containing magnesium, and certain antibiotics.
  • Infectious diseases such as traveler’s diarrhea, typhoid fever, amoebic dysentery, and bacillary dysentery (shigellosis).
  • Emotional stress and anxiety.
  • Persistent diarrhea, often alternating with bouts of constipation, may be caused by irritable bowel syndrome.

Other causes for acute diarrhea include autoimmune diseases and vascular problems.

What If You Do Nothing?

Fortunately, simple diarrhea is usually self-limiting—it gets better without treatment in a day or two as long as you drink plenty of fluids. However, diarrhea can have serious consequences when it causes dehydration.


  • Diarrhea may be self-diagnosed by the observation of characteristic symptoms. Laboratory stool analysis may be warranted in cases of persistent diarrhea and blood tests may be used to rule out certain diseases.
  • Colonoscopy with a biopsy from the colon may help to diagnose viral, bacterial, or inflammatory causes of diarrhea.


Treatment for diarrhea depends on the underlying cause, the severity of the condition, and the overall health of the person. In most cases, treatment simply involves replacing fluids and electrolytes (i.e., minerals and salts used in important body functions).

  • If persistent diarrhea occurs in an infant, contact your pediatrician, who may recommend giving the baby an electrolyte solution (available over-the-counter from a pharmacist) and reintroducing formula gradually over a 24-hour period.
  • Prevent dehydration (especially important for young children and the elderly) by drinking a solution of one teaspoon of salt and four teaspoons of sugar in one quart of water. Measure accurately: too much salt may worsen dehydration. Drink one pint of solution each hour while diarrhea lasts.
  • Healthy adults with little or no dehydration can usually manage diarrhea and maintain adequate rehydration by drinking several types of clear liquids—fruit juices, clear broths, flat (de-fizzed) soft drinks, etc. Sip small amounts for the first few hours and increase your intake slowly. Try to drink at least one pint of fluid (16 ounces) every hour.
  • Medications that may be helpful include loperamide (e.g., Imodium A-D) or bismuth subsalicylate (e.g., Pepto-Bismol). However, talk to your health care provider before taking over-the-counter antidiarrheal medicines—they should not be used to treat diarrhea caused by a bacterial or parasitic infection—and do not take antidiarrheal medications for the first few hours—the diarrhea may be ridding your body of infectious agents or irritants. In some cases, antibiotics are prescribed to treat these infections.
  • Limit (or avoid) milk products, alcohol, caffeine, and foods rich in fiber during recovery. Avoid products containing the sweeteners sorbitol, xylitol, and mannitol, which are commonly found in sugarless gum, vitamins, and diet foods.
  • If you suspect diarrhea is caused by food poisoning, you are probably better off letting the condition run its course. This allows you to get the harmful bacteria and/or toxins completely out of your system. (Traveler’s diarrhea, however, may require different strategies.)
  • If you suspect diarrhea is caused by a medication, call your doctor. This is especially true if you are taking an antibiotic.


  • Do not eat food that you suspect has spoiled.
  • Avoid foods to which you are sensitive.
  • When traveling abroad, drink only bottled or boiled water or other bottled beverages. Eat cooked foods and fruit you can peel yourself. Local water or raw foods may contain bacteria that can cause diarrhea.
  • Learn ways of coping with emotional stress, and try to avoid stressful situations.

When to Call Your Doctor

Call a doctor if diarrhea persists for more than 48 hours or is accompanied by any of the following:

  • Severe cramping/severe abdominal pain.
  • Persist vomiting.
  • Inability to tolerate oral intake.
  • Fever over 101°F.
  • Blood in the stool.

Talk to your health care provider if diarrhea recurs frequently or there are frequent bouts of diarrhea and constipation, since this may be a sign of an underlying disorder.

EMERGENCY Call a doctor promptly if an infant or elderly person shows symptoms of dehydration.

Reviewed by Michael S. Soliman, M.D., family medicine physician in private practice and hospitalist at Mount Holyoke Medical Center, Mount Holyoke, MA.