Antibiotic therapy in small intestinal bacterial overgrowth: rifaximin versus metronidazole

Eur Rev Med Pharmacol Sci. 2009 Mar-Apr;13(2):111-6.


Background and objectives: Few controlled trials on antibiotic therapy for small intestinal bacterial overgrowth are available at present. Aim of the study was to assess efficacy, safety and tolerability of rifaximin with respect to metronidazole for the treatment of small intestinal bacterial overgrowth.

Material and methods: We enrolled 142 consecutive patients with diagnosis of small intestinal bacterial overgrowth. Diagnosis of small intestinal bacterial overgrowth based on the clinical history and the positivity of glucose breath test. Patients were randomised to two 7-day treatment groups: rifaximin 1200 mg/day and metronidazole 750 mg/day. Glucose breath test was reassessed 1 month after. Compliance and side-effect incidence were also evaluated.

Results: One drop-out was observed in rifaximin group. Five drops-out occurred in metronidazole group. The glucose breath test normalization rate was significantly higher in the rifaximin with respect to the metronidazole group (63.4% versus 43.7%; p < 0.05; OR 1.50, 95% CI 1.14-4.38). The overall prevalence of adverse events was significantly lower in rifaximin with respect to metronidazole group.

Discussion: Rifaximin showed an higher SIBO decontamination rate than metronidazole at the tested doses, both with a significant gain in terms of tolerability. Either the present study or recent evidencies suggest that rifaximin represents a good choice for the management of patients affected by SIBO.

Publication types

  • Comparative Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Anti-Infective Agents / adverse effects
  • Anti-Infective Agents / therapeutic use*
  • Bacterial Infections / diagnosis
  • Bacterial Infections / drug therapy*
  • Breath Tests / methods
  • Female
  • Glucose / analysis
  • Humans
  • Intestine, Small / microbiology
  • Male
  • Medication Adherence
  • Metronidazole / adverse effects
  • Metronidazole / therapeutic use*
  • Middle Aged
  • Prospective Studies
  • Rifamycins / adverse effects
  • Rifamycins / therapeutic use*
  • Rifaximin
  • Young Adult


  • Anti-Infective Agents
  • Rifamycins
  • Metronidazole
  • Glucose
  • Rifaximin