Antibiotics as a Treatment for IBS

A relatively new area of IBS research has been a focus on the use of antibiotics as a potential treatment. Not all antibiotics are thought to be helpful for IBS, just those that are not absorbed by the stomach and therefore can have an effect on bacteria within the small and large intestine. When prescribed as a treatment for IBS, antibiotics are only used on a short-term basis.

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Why Use Antibiotics

The use of antibiotics for IBS came about when researchers looked at similarities between IBS and small intestinal bacteria overgrowth (SIBO). SIBO is a condition in which excess bacteria are found within the small intestine. Using hydrogen breath testing, researchers have found that a certain sub-set of IBS patients appeared to suffer from SIBO. Non-absorbable antibiotics were then tested for their effects on IBS symptoms.

The following antibiotics have been tested as to their effectiveness in treating IBS:

  • Rifaximin (Xifaxan)
  • Neomycin
  • Clarithromycin (Biaxin)
  • Metronidazole (Flagyl)


Of the above antibiotics, Xifaxin is the only medication that has consistently been shown to be superior to placebo in easing symptoms in a subset of IBS patients. Xifaxan appears to be most effective at relieving symptoms of bloating and diarrhea. Xifaxan is generally well-tolerated and no serious side effects have been noted.

Bottom Line

As of now, only Xifaxan is approved by the FDA as a treatment for non-constipation IBS. It is important to know that most of the studies to date on the use of antibiotics for IBS have been of a short-term nature. Further research needs to be conducted to assess long-term safety and effectiveness of these medications, as well as to better identify those patients who will best benefit from this type of treatment.

4 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Basseri RJ, Weitsman S, Barlow GM, Pimentel M. Antibiotics for the treatment of irritable bowel syndromeGastroenterol Hepatol (N Y); 7(7):455–493.

  2. Sainsbury A, Ford AC. Treatment of irritable bowel syndrome: beyond fiber and antispasmodic agentsTherap Adv Gastroenterol. 2011;4(2):115–127. doi:10.1177/1756283X10387203

  3. Ford AC, Moayyedi P, Chey WD, et al. American College of Gastroenterology monograph on management of irritable bowel syndrome. Am J Gastroenterol. 2018;113(Suppl 2):1-18. doi:10.1038/s41395-018-0084-x

  4. U.S. Food and Drug Administration. Xifaxan (rifaximin) tablets, for oral use.

By Barbara Bolen, PhD
Barbara Bolen, PhD, is a licensed clinical psychologist and health coach. She has written multiple books focused on living with irritable bowel syndrome.