Rifaximin (Xifaxan ®) is the only antibiotic approved by the FDA for treatment of IBS-D. Its exact mechanism of action is unknown. Studies have suggested that it works by modifying bacterial structure or function in the gut potentially targeting the small intestine. It also appears to have anti-inflammatory properties. Rifaximin improves overall IBS-D symptoms.
This drug differs from other IBS-D treatments as it is only taken for 2- weeks. If Rifaximin is beneficial, symptom relief should occur following the 2-week treatment. Symptoms may return after the initial treatment, and 2 successive treatments are allowed. It is minimally absorbed and generally well tolerated. The most commonly experienced adverse event is nausea.
Taken from IFFGD Publication #168- Current Pharmacologic Treatments for Adults with Irritable Bowel Syndrome By: Darren M. Brenner, MD, Associate Professor of Medicine and Surgery, Northwestern University – Feinberg School of Medicine, Chicago, Illinois; Adapted from an article by: Tony Lembo, MD, Professor, of Medicine and Rebecca Rink MS, Beth Israel Deaconess Medical Center, Harvard Medical School, MA; Edited by: Lin Chang, M.D., Professor of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA