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Broad and learned
clinical background

Gut Reaction #29: Rifaximin in IBS and SIBO

Rifaximin is an antibiotic that can be used to treat irritable bowel syndrome without constipation (IBS) and small intestinal bacterial overgrowth (SIBO) and if successful, may relief abdominal pain, bloating and diarrhoea. Individuals with IBS and/or SIBO are thought to have abnormal biodiversity of the gut microbiome. The overgrowth of gut bacteria may lead to excessive gas production and malabsorption of certain carbohydrates (see last month’s blog) leading to symptoms, such as diarrhoea, gas bloating and abdominal pain. Rifaximin may improve the biodiversity and thus improve symptoms.

It’s worth noting that the rifaximin is usually well-tolerated and has few side effects, predominantly because less than 0.5% of the oral dose is absorbed from the gut. However, patients may still experience mild symptoms such as nausea, dizziness and fatigue. The drug does not appear to lead to bacterial resistance nor an increase in risk of Clostridium difficile infection (a concern when using broad-spectrum antibiotics).

If used to treat SIBO repeated courses may be required if symptoms return. Recurrence of SIBO may occur after rifaximin treatment in around 15% of patients at 3 months, 30% of patients at 6 months and 40% of patients at 9 months. If this is confirmed by a lactulose hydrogen breath test, further treatment may be required.

Rifaximin comes in tablet form (400mg) and is usually taken 3 times daily for 10 days. It can be taken with or without food. However, the high cost of rifaximin has limited its use; it is not a treatment option as an NHS patient.

If you have any questions about rifaximin or the treatment of IBS or SIBO, please do not hesitate to contact Dr. Harris.