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Xifaxan And Other Antibiotics

One of the factors that is believed to cause or trigger irritable bowel syndrome (IBS) is the overgrowth of harmful bacteria in the intestines. Because of this, gut-specific antibiotics are often prescribed for patients with IBS, particularly those patients who complain of gas, bloating symptoms, abdominal pain, and diarrhea.1,2 Antibiotics are medicines that fight bacterial infections. They either kill bacteria or keep them from reproducing.3

The most studied antibiotic in IBS treatment is rifaximin, brand name Xifaxan. Xifaxan is minimally absorbed by the gastrointestinal tract, which allows more of the medication to remain in the intestines. Also, this means there is less of the medication in the rest of the body. Xifaxan does not seem to significantly alter the natural microflora (good bacteria) in the gut, and it does not cause diarrhea like some antibiotics may.1

What is Xifaxan?

Xifaxan is a prescription medication used in adults with IBS with diarrhea (IBS-D). Patients treated for two weeks with Xifaxan may get 6-24 weeks of relief from IBS-D symptoms, including abdominal pain and diarrhea. On average, patients in a clinical trial with Xifaxan experienced 10 weeks of relief. Patients can be retreated with Xifaxan up to two times if symptoms come back.4

How to take Xifaxan

Xifaxan comes in a 550mg tablet form and must be taken three times a day for two weeks. The tablets can be taken with or without food. It is important to take the entire course of treatment – three tablets a day for 14 consecutive days – to experience the effectiveness of the treatment. Treatment should not be discontinued even if the patient starts to feel relief from IBS symptoms. If a dose is missed, it should be taken as soon as it is remembered. However, if it is time for the next dose, the missed dose should be skipped. Double doses to make up for the forgotten dose are not recommended.3,4

Before taking Xifaxan, patients should discuss with their doctor all medications and supplements they are currently taking, especially cyclosporine or any other antibiotics. Patients who are allergic to rifaximin should not take Xifaxan. Patients who are pregnant, planning to become pregnant, or breastfeeding, should discuss their condition with their doctor before taking Xifaxan as it is unknown whether the medication might harm the baby.3,4

Xifaxan side effects

The most common side effects experienced by patients taking Xifaxan are peripheral edema, dizziness, nausea, headache, fatigue and an increase in liver enzymes (specifically Alanine aminotransferase, or ALT). These are not all the possible side effects of Xifaxan. Patients should talk to their doctor about what to expect with treatment with Xifaxan.

Other antibiotics for IBS

There have been some studies that have shown another antibiotic, neomycin, to be effective in treating IBS-D. However, there are more side effects with neomycin. Systemic antibiotics, those that are absorbed and circulate throughout the body, have not been well studied as a treatment for IBS.1

Other IBS treatments

Often, patients with IBS have to try several treatment options to find what works best for them. Many patients may find that a combination of treatment approaches helps manage their symptoms. In addition to antibiotics, other treatment options for IBS include adding exercise, making dietary changes, adding fiber, using probiotics, getting counseling, or trying complementary or alternative medicine.

Written by: Emily Downward | Last reviewed: July 2019
  1. Lacy BE, Chey WD, Lembo AJ. New and emerging treatment options for irritable bowel syndrome. Gastroenterol Hepatol (N Y). 2015 Apr;11(4 Suppl 2):1-19.
  2. Sayuk GS, Gyawali CP. Irritable bowel syndrome: modern concepts and management options. Am J Med. 2015 Aug;128(8):817-27.
  3. MedlinePlus, U.S. National Library of Medicine. Accessed online on 3/10/16 at
  4. Xifaxan product website, Salix Pharmaceuticals. Accessed online on 3/10/16 at