Breath Testing for Small Intestinal Bacterial Overgrowth: Should We Bother?

Am J Gastroenterol. 2016 Mar;111(3):307-8. doi: 10.1038/ajg.2016.30. Epub 2016 Feb 23.


The hydrogen breath test is based on following breath hydrogen levels after the administration of a carbohydrate (most commonly lactulose) to a patient with suspected small intestinal bacterial overgrowth. The test is based on the interaction between the administered carbohydrate and the intestinal bacteria. The resulting fermentation produces hydrogen. A positive breath test is based on a breath hydrogen rise prior to the expected arrival time in the highly microbial cecum. Despite renewed enthusiasm for breath testing in recent years due to associations with conditions such as irritable bowel syndrome, breath testing poses many challenges. In this argument against breath testing, several pitfalls that complicate breath testing will be described.

MeSH terms

  • Breath Tests / methods*
  • Dimensional Measurement Accuracy
  • Gastrointestinal Agents / pharmacology
  • Gastrointestinal Microbiome / physiology
  • Humans
  • Hydrogen / analysis
  • Intestine, Small / microbiology*
  • Irritable Bowel Syndrome / diagnosis*
  • Irritable Bowel Syndrome / microbiology
  • Lactulose / pharmacology
  • Lactulose / physiology
  • Reproducibility of Results


  • Gastrointestinal Agents
  • Lactulose
  • Hydrogen