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Small intestinal bacterial overgrowth: Management

Mark Pimentel, MD, FRCP(C)
Section Editor
J Thomas Lamont, MD
Deputy Editor
Shilpa Grover, MD, MPH, AGAF


Small intestinal bacterial overgrowth (SIBO) is a condition in which the small bowel is colonized by excessive aerobic and anaerobic microbes that are normally present in the colon. The majority of patients with SIBO present with bloating, flatulence, abdominal discomfort, or diarrhea. This topic will review the management of SIBO. The etiology, pathogenesis, clinical manifestations, and diagnosis of SIBO are presented separately. (See "Small intestinal bacterial overgrowth: Clinical manifestations and diagnosis".)


The mainstay of therapy for SIBO are antibiotics to reduce (rather than eradicate) small intestinal bacteria. In addition, some patients require treatment of underlying nutritional deficiencies and associated ileitis/colitis.

Antibiotic therapy — Antibiotic therapy is typically begun on an empiric basis. The selection of antimicrobial regimens is based on the pattern of bacterial overgrowth, the prevalence of risk factors for drug-resistance (recent or repeated prior exposure), relevant antibiotic allergies, and cost [1]. It is unnecessary to repeat breath testing if symptoms resolve with treatment. (See "Small intestinal bacterial overgrowth: Clinical manifestations and diagnosis", section on 'Carbohydrate breath test'.)

Hydrogen-predominant bacterial overgrowth — In patients with hydrogen predominant bacterial overgrowth without excess methane production, we use rifaximin (1650 mg/day for 14 days). Rifaximin is nonabsorbable rifamycin derivative. It is well tolerated and has been demonstrated to be effective in the treatment of SIBO [2-8]. However, the high cost of rifaximin has limited its use.

Methane-predominant bacterial overgrowth In patients with methane-predominant bacterial overgrowth, we use a combination of neomycin 500 mg twice daily and rifaximin 550 mg three times daily for 14 days [9].

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Literature review current through: Nov 2017. | This topic last updated: Jul 27, 2017.
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