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For the Chapter in the Schwinghammer, Handbook (not Wells Handbook anymore) please go to Chapter 22, Constipation and Chapter 23, Diarrhea.



  • imageDiarrhea is caused by many viral and bacterial organisms. It is most often a minor discomfort, not life-threatening, and usually self-limited.

  • imageThe four pathophysiologic mechanisms of diarrhea have been linked to the four broad diarrheal groups, which are secretory, osmotic, exudative, and altered intestinal transit. The three mechanisms by which absorption occurs from the intestines are active transport, diffusion, and solvent drag.

  • imageManagement of diarrhea focuses on preventing excessive water and electrolyte losses, dietary care, relieving symptoms, treating curable causes, and treating secondary disorders.

  • imageBismuth subsalicylate is marketed for indigestion, relieving abdominal cramps, and controlling diarrhea, including traveler’s diarrhea, but may cause interactions with several components if given excessively.

  • imageConstipation is defined as difficult or infrequent passage of stool, at times associated with straining or a feeling of incomplete defecation.

  • imageUnderlying causes of constipation should be identified when possible and corrective measures taken (eg, alteration of diet or treatment of diseases such as hypothyroidism).

  • imageThe foundation of treatment of constipation is dietary fiber or bulk-forming laxatives that provide 20 to 25 g/day of raw fiber.

  • imageIrritable bowel syndrome (IBS) is one of the most common GI disorders characterized by lower abdominal pain, disturbed defecation, and bloating. Many non-GI manifestations also exist with IBS. Visceral hypersensitivity is a major culprit in the pathophysiology of the disease.

  • imageDiarrhea-predominant IBS should be managed by dietary modification and drugs such as loperamide when diet changes alone are insufficient to promote control of symptoms.

  • imageSeveral drug classes are involved in the treatment of the pain associated with IBS including tricyclic compounds and the gut-selective calcium channel blockers.


Patient Care Process for Diarrhea



  • Patient characteristics

  • Patient medical, family, social history, and dietary habits

  • Current medications, including nonprescription

  • Vital signs and weight

  • Laboratory tests depending upon medical history and other presenting symptoms

    • Thyroid function tests, complete blood count, glucose, serum electrolytes


  • Underlying causes of diarrhea (see Tables 53-1 and 53-2)

  • Severity and duration of symptoms

  • Patient preference for symptom resolution

  • Ability/willingness to pay for treatment options


  • Treat specific cause of diarrhea (ie, diabetes, infectious, etc.)

  • Increase fluid intake using oral rehydration solutions (Table 53-3)

  • Antidiarrheal medication (Table 53-4)

  • Monitor symptom resolution for efficacy, and pronounced constipation for safety

  • Patient education regarding importance of prevention dehydration

  • Referral to other providers when appropriate


  • Educate the patient on all aspects of the treatment plan

  • Schedule follow-up to monitor safety and efficacy of treatment plan

Follow-up: Monitor and Evaluate

  • Determine resolution of diarrhea and related symptoms

  • Evaluate for signs and symptoms of dehydration

  • Assess for presence of adverse effects (eg, abdominal pain, constipation)

  • Assess patient adherence to treatment plan

  • Reevaluate periodically until ...

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