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Do Antibiotics Help IBS?


Updated December 29, 2012

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

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.

Why Are Antibiotics Used for IBS?

The use of antibiotics for IBS came about when researchers looked at similarities between IBS and small intestine 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.

What Kinds Are Used?

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

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

Are They Effective?

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.

The Bottom Line

As of now, no antibiotics have been approved of by the FDA as a treatment for IBS, although Xifaxan is currently undergoing review as a treatment for non-constipation IBS. It is important to know that most of the studies to date 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.

Essential Reading:


American College of Gastroenterology IBS Task Force. "An Evidence-Based Position Statement on the Management of Irritable Bowel Syndrome". American Journal of Gastroenterology 2009:S1-S35.

Gaman, A., Bucur, M. & Kuo, B. Therapeutic advances in functional gastrointestinal disease: irritable bowel syndrome. Therapeutic Advances in Gastroenterology 2009 2:169-181.

Sainsbury, A. & Ford, A. "Treatment of Irritable Bowel Syndrome: Beyond Fiber and Antispasmodic Agents." Therapeutic Advances in Gastroenterology 2011 4:115-127.

DISCLAIMER: The information contained on this site is for educational purposes only and should not be used as a substitute for diagnosis or treatment rendered by a licensed physician. It is essential that you discuss with your doctor any symptoms or medical problems that you may be experiencing.

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