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Loperamide-Simethicone Has a Role in Treating Acute Self-Limited Diarrhea


  • You are seeing a 13 year-old with acute diarrhea. Her parents wonder whether simethicone drops or other medications are safe and effective treatments. The question is: Among children with diarrhea and abdominal pain related to acute uncomplicated gastroenteritis, does simethicone compared to placebo decrease symptoms related to diarrhea?

Clinical Bottom Lines

  1. There are no studies looking at simethicone alone in diarrhea and no studies in children.
  2. The combination of loperamide-simethicone has been shown in adults to be safe and effective in treating abdominal pain and diarrhea secondary to acute gastroenteritis.1
  3. This method is NOT TO BE USED if high fever, gross blood or pus in stool, or severe symptoms (requiring hospitalization, IVF), or if the patient has chronic GI disease.
  4. Loperamide is not approved for use under 2yrs of age but simethicone is generally accepted at all age levels. escribe clinical actions to be taken based on the results of your critical appraisal

Summary of Key Evidence

  1. This is a randomized, double blinded, placebo controlled trial among simethicone alone, loperamide alone, and combination loperamide-simethicone.1
  2. Patients received blinded identical chewable tablets and kept ongoing records of timing and consistency of stools and degree of abdominal pain for 48hrs.
  3. The groups were similar, except that there were more people with more severe disease in the combination group.
  4. Combination loperamide-simethicone users had lower time to resolution of diarrhea vs placebo (9.7 vs 39.0 hrs, p<.001) and shorter time to resolution of abdominal pain (12.0 vs 48.0 hrs, p<.001). Users of simethicone or loperamide alone had smaller but still statistically significant reductions vs placebo.
  5. Compared to placebo, for every two patients treated with the combination, one person will no longer have diarrhea at 24 hours (NNT=2).
  6. No adverse events were reported, but the study was not powered to detect these.

Additional Comments

  • No studies exist in pediatric population
  • There was no attempt to account for different infectious causes, but because the study was done with tourists in Acapulco, they may have been primarily treating traveler's diarrhea
  • Unclear mechanism of synergistic effect of the two medications, but some studies have shown that simethicone delays the absorption of loperamide
  • Both medications are available OTC
  • This study was reviewed in ACP Journal Club, and they agreed with these conclusions.2


  1. Kaplan MA, et al. Loperamide-simethicone vs loperamide alone, simethicone alone, and placebo in the treatment of acute diarrhea with gas-related abdominal discomfort. A randomized controlled trial. Archives of Family Medicine. 1999; 8(3):243-8.
  2. Calva JJ. Commentary. ACP Journal Club 1999;131:66-67.

CAT Author: David A. Basel, MD

CAT Appraisers: John G. Frohna, MD

Date appraised: July 16, 2001

Last updated October 28, 2002
Department of Pediatrics and Communicable Diseases
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