Small Intestinal Bacterial Overgrowth Syndrome: A Guide for the Appropriate Use of Breath Testing

Dig Dis Sci. 2021 Feb;66(2):338-347. doi: 10.1007/s10620-020-06623-6. Epub 2020 Oct 10.


The increased availability of noninvasive breath tests, each with limitations, has led to widespread testing for small intestinal bacterial overgrowth (SIBO) in patients with non-specific gastrointestinal complaints. The lactulose breath test (LBT) is based upon an incorrect premise and therefore incorrect interpretations which has resulted in the over-diagnosis of SIBO and the excessive use of antibiotics in clinical practice. Despite limitations, the glucose breath test (GBT) should be exclusively employed when considering SIBO in appropriately chosen patients. This review suggests guidelines for the optimal use and appropriate interpretation of the GBT for suspected SIBO. The LBT should be discarded from future use, and the literature based upon the LBT should be discounted accordingly.

Keywords: Gastrointestinal radionuclide imaging; Glucose and lactulose breath tests; Hydrogen gas; Methane gas; Small intestinal bacterial overgrowth.

Publication types

  • Editorial
  • Review

MeSH terms

  • Blind Loop Syndrome / diagnosis*
  • Blind Loop Syndrome / metabolism*
  • Breath Tests / methods
  • Glucose / metabolism
  • Intestine, Small / metabolism*
  • Intestine, Small / microbiology
  • Practice Guidelines as Topic / standards*


  • Glucose