Skip to Main Content

Source: Powell PH and Fleming VH. Diarrhea, Constipation, and Irritable Bowel Syndrome. In: DiPiro, JT, Talbert RL, Yee GC, Matzke GR, Wells BG, Posey LM. Pharmacotherapy: A Pathophysiologic Approach. 8th ed. Accessed May 15, 2012.

  • Self-limited increase in frequency and decrease in consistency of fecal discharge primarily due to viral, bacterial, or protozoal infection.

  • Most common bacterial causes: Shigella, Salmonella, Campylobacter, Staphylococcus, and Escherichia coli
  • Most common viral causes: Norwalk and rotavirus
  • Medications (Table 1)

Table 1. Drugs Causing Diarrhea

  • Imbalance in absorption and secretion of water and electrolytes due to:
    • Change in active ion transport by decreased sodium absorption or increased chloride secretion (secretory diarrhea)
    • Change in intestinal motility caused by:
      • Reduced contact time in small intestine
      • Premature emptying of colon
      • Bacterial overgrowth
    • Increase in luminal osmolarity
    • Increase in tissue hydrostatic pressure

  • Initiate isolation techniques in daycare centers and nursing homes to prevent transmission of viral illness.
  • Practice strict food handling, sanitation, water and other environmental hygiene practices to prevent transmission of bacterial, parasitic, and protozoal infections.
  • Treat drinking water and limit consumption of fresh vegetables; in addition, prophylactic antibiotics and bismuth subsalicylate may be indicated when traveling.

Signs and Symptoms

  • Acute diarrheal episodes subside within 72 hours of onset.
  • Chronic diarrhea involves frequent attacks over extended periods of time.
  • Abrupt onset of:
    • Nausea
    • Vomiting
    • Abdominal pain
    • Headache
    • Fever
    • Chills
    • Malaise
  • Frequent, non-bloody bowel movements over 12–60 hours
  • Pain described as gripping or aching localized to:
    • Hypogastric region
    • Left or right lower quadrant
    • Sacral region
  • Chronic diarrhea associated with:
    • Weight loss
    • Anorexia
    • Chronic weakness
  • Physical exam demonstrates hyperperistalsis with borborygmi and generalized or local tenderness.

Laboratory Tests

  • Stool analysis for microorganisms, blood, mucus, fat, osmolality, pH, electrolyte and mineral concentration
  • Stool cultures
  • Stool test kits for detecting viruses, particularly rotavirus


  • Radiographic studies helpful in neoplastic and inflammatory conditions.

Diagnostic Procedures

  • Assess for presence of colitis or cancer through direct endoscopic visualization and biopsy of colon.

  • Manage diet.
  • Prevent excessive water, electrolyte, and acid-base disturbances.
  • Provide symptomatic relief.
  • Treat curable causes of diarrhea.
  • Manage secondary disorders.
  • Keep in mind that diarrhea may be defense mechanism that needs to run its course.

  • Manage dietary intake (Figs. 1 and 2)
    • Stop solid foods for 24 hours.
    • Avoid dairy products.
    • Use digestible, low-residue diet for 24 hours when mild nausea or vomiting also present.
    • Take nothing by mouth if ...

Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.