Rifaximin (Xifaxan) for Irritable Bowel Syndrome (IBS) Treatment

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Irritable bowel syndrome, or IBS, is a common gastrointestinal syndrome that may affect up to 15% of the population in the U.S. The primary symptom of IBS is abdominal discomfort that is associated with either an alteration in bowel habit (diarrhea, constipation, or diarrhea alternating with constipation) or that is improved with a bowel movement. In fact, the alteration in bowel habit is used to subgroup patients into three clinically separate groups. It is not certain if the cause (etiology) is the same for all groups or if each group has a distinct and separate cause. Various theories regarding the causes of IBS include:

  • abnormalities of the function of the intestinal muscles or their controlling nerves,
  • abnormal intestinal neural sensation,
  • altered immunology of the intestine,
  • intestinal inflammation, and
  • alteration or overgrowth of the bacteria that colonize the intestine.

The last of these potential causes (etiologies) - bacterial alteration or overgrowth - has been explored in an important scientific study recently published in the New England Journal of Medicine by Pimentel et al. In this study, the authors randomized over 1,000 patients with IBS not associated with predominant constipation (i.e., they had mostly normal and/or diarrheal bowel habits) to receive either an antibiotic, rifaximin (Xifaxan), or a placebo (an inactive pill) for two weeks. The patients were followed during treatment and for up to 10 weeks after completing treatment to assess the effects of treatment on their symptoms. With respect to symptoms, the patients receiving rifaximin did better than the patients receiving placebo, and the difference was statistically significant.

Medically Reviewed by a Doctor on 12/1/2014