Breath Test Identifies IBS Patients Who Benefit from Antibiotics
Refined Lactulose Hydrogen Breath Test for Small Intestinal Bacterial Overgrowth Subgrouping Irritable Bowel Syndrome With Low and High Breath Hydrogen
Research hubs: Digestive System
- Evidence type
- Observational study · Human study
- Authors
- A Dahlgren, P Grybäck, H Jacobsson, P M Hellström
- Journal
- Gastroenterology Research and Practice
- Year
- 2025
- PMID
- 40990001
- Study Type
- Human
- Participants
- 206
- Delivery
- Gas
- H₂ concentration
- 20 ppm
- Outcome
- Neutral
- Peer Reviewed
- Yes
- Cited by
- 2 (OpenAlex, as of November 2026)
- Country
- Sweden
TL;DR
A hydrogen breath test cutoff of 20 ppm helps identify IBS patients with SIBO who are more likely to improve with antibiotics.
Key Finding
A lactulose hydrogen breath test cutoff of 20 ppm can differentiate SIBO from non-SIBO cases and divide IBS patients into two groups—those with high hydrogen levels who respond to antibiotics and those with low hydrogen levels who do not.
Summary
This study tested a breath test method (lactulose hydrogen breath test) to identify small intestinal bacterial overgrowth (SIBO)—a condition where bacteria grow excessively in the small intestine—in people with irritable bowel syndrome (IBS). Researchers measured hydrogen levels in breath samples from healthy people, SIBO patients, and IBS patients, and found that a threshold of 20 parts per million could distinguish between those with and without SIBO. Importantly, IBS patients were divided into two groups: those with high hydrogen levels (who improved with antibiotics) and those with low hydrogen levels (who did not improve with antibiotics).
Practical Takeaway
This study suggests that hydrogen breath testing may help identify which IBS patients have SIBO and could benefit from antibiotic treatment. However, this is a diagnostic study focused on test accuracy rather than hydrogen water itself, so it does not directly address whether consuming hydrogen-enriched water has health benefits. The findings are relevant mainly to people interested in understanding their IBS symptoms through breath testing.
Abstract (excerpt)
Background: Small intestinal bacterial overgrowth (SIBO) is suggested in irritable bowel syndrome (IBS). Our primary aim was to define a discriminating threshold for a positive lactulose hydrogen breath test (LHBT) in SIBO. As a secondary aim, IBS was subdivided into SIBO and non‐SIBO groups…