Loose Stool

What is Diarrhea?

Diarrhea is an increase in the fluidity, frequency, and/or volume of bowel movements as compared to the usual pattern for a particular individual.

A symptom of an underlying condition, diarrhea may be acute or chronic. In normal bowel activity, the large intestine (colon) absorbs much of the water from the liquid food residues that pass through it, resulting in semisolid feces.

Diarrhea results when the intestinal contents pass through the colon too quickly, or when an inflamed small intestine secrets fluid back into the fecal material.

The cause of diarrhea, in most cases, is unknown. Many individuals contract diarrhea through infections (bacterial, parasitic, viral) that usually occur after the ingestion of contaminated food or water. Infections may also be transmitted person-to-person through contaminated hands or objects, or in some cases through droplet infection (adenoviruses, echoviruses).

Diarrhea may also be caused by anxiety, failure to absorb certain foods (lactase deficiency, glutens), drugs (including some antibiotics) that interfere with the harmless bacteria normally found in the intestines, ingestion of magnesium laxatives or antacids, drug toxicity, immune disorders (Crohn's disease, ulcerative colitis), hormone abnormalities (carcinoid syndrome, thyrotoxicosis), cancer of the large intestine, diverticular disease, irritable bowel syndrome, fecal impaction, lack of blood and oxygen to portions of the intestines (ischemic disease), following radiation therapy, and with certain surgical procedures (stomach, ileum).

Diarrhea may also be associated with infectious processes outside the gastrointestinal tract, such as pneumonia, urinary tract infection, and pelvic inflammatory disease.

How is it diagnosed?

History: Symptoms may include bowel movements that are increased in fluidity, frequency, or volume compared to the individual's usual pattern. Blood, mucus, or pus may be present in the stool when there is damage to the mucous lining of the intestinal tract. Individuals who are lactose deficient may have developed diarrhea from milk and milk products. Other symptoms often associated with diarrhea include nausea, vomiting, and fever. Individuals may report family or friends with diarrhea or a history of recent travel.

Physical exam is usually normal, although abdominal tenderness may be present. If diarrhea has been of sufficient length to cause dehydration, physical exam may show dry mouth, decreased blood pressure, weakness, lethargy, or confusion. There may also be evidence of increased skin pigmentation, or inflammation of the tongue (glossitis).

Tests: In most cases of acute diarrhea, laboratory investigation is unnecessary, unrevealing, and does not affect treatment or outcome. Microscopic examination of the stool for leukocytes (white blood cells) distinguishes non-inflammatory from inflammatory diarrhea. If leukocytes are present, a stool culture is done to identify the infectious agent. If diarrhea persists for more than ten days, examinations are done on three consecutive stools to look for ova or parasites.

In cases of chronic diarrhea, additional tests may include 24-hour stool collection for weight and quantitative fecal fat (to identify a malabsorption process), a stool laxative screen to rule out laxative abuse, and a stool osmolality to rule out lactase deficiency, laxative abuse, or malabsorption syndromes. Routine laboratory tests to rule out malabsorption, anemia, and inflammatory diseases include complete blood count (CBC), serum electrolytes, liver function tests, calcium, phosphorus, albumin, TSH, total T4, beta-carotene, and prothrombin.

In individuals with severe inflammation of the rectum or anus, a sigmoidoscopy (direct visualization of the sigmoid colon and rectum by using a magnified viewing tube inserted up into the rectum) with mucosal biopsy (removal of small sample of mucous membrane for microscopic analysis) is warranted to distinguish infectious diarrhea from ulcerative colitis or ischemic colitis.

X-ray studies of the digestive tract, using barium as the contrast medium, are useful in detecting abnormal narrowing (strictures) or other anatomic abnormalities beyond the reach of the sigmoidoscope.

How is Diarrhea treated?

Antidiarrheal drugs should not be used when diarrhea is caused by an infection because they may prolong the illness.

Treatment is directed at the underlying cause of the diarrhea. Most cases of acute diarrhea do not require any treatment other than oral fluids (containing carbohydrates and electrolytes) and temporary diet modification (avoiding solid food until diarrhea subsides).

Antibiotic or antimicrobial therapy may be necessary when severe diarrhea is due to an infectious agent. Antidiarrheal drugs may be used as a comfort measure. However, they should not be used in cases where diarrhea is caused by infection, as they may prolong the illness.

In chronic diarrhea, intravenous fluid and electrolyte replacement may be required if dehydration is severe. Otherwise, therapy is directed at the underlying disease. Offending drugs should be discontinued, if possible.

Diet modification may be necessary to exclude gluten or dairy products.

Antibiotics are used to treat bacterial overgrowth, tumors are treated with surgery or chemotherapy, and pancreatic enzymes are used to treat pancreatic insufficiency.

Bulk forming agents are used in the treatment of irritable bowel syndrome and disorders involving the anus or rectum.

Fecal impaction may be resolved with the manual removal of the impaction.


Information Brand Generic Label Rating
http://www.nmihi.com/a/azithromycin.html Zithromax Azithromycin Off-Label
Imodium Loperamide On-Label


  • If diarrhea is accompanied by nausea, suck ice chips only.
  • If you are not nauseated, drink small amounts of clear liquids only, such as herbal tea, ginger ale, broth or gelatin until diarrhea stops.
  • Avoid alcohol, caffeine, milk and dairy products.
  • After symptoms disappear, eat soft foods, such as cooked cereal, rice, eggs, custard, baked potato and yogurt for 1 or 2 days.
  • Resume a normal diet 2 or 3 days after the diarrhea stops. Avoid fruit, alcohol and highly seasoned foods for several more days.

What might complicate it?

The most common complications of diarrhea are dehydration and electrolyte imbalance.

Predicted outcome

In over 90% of the cases, acute diarrhea is mild, self-limited, and responds within five days to rehydration therapy or antidiarrheal agents. Individuals with diarrhea caused by infectious agents will recover with appropriate antibiotic therapy. Diarrhea resulting from other causes will improve with treatment of the underlying condition. Individuals with diarrhea of probable immune cause may have chronic inflammation with bouts of diarrhea for years.


Conditions that may result in diarrhea include bowel obstruction, inflammatory bowel disease, irritable bowel syndrome, diabetic neuropathy, or anal sphincter abnormalities.

Appropriate specialists

Internist and gastroenterologist.

Last updated 22 December 2011

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