Reglan and H. pylori Breath Test
Reglan (metoclopramide) does not interfere with the H. pylori urea breath test and does not need to be discontinued before testing.
Key Medications That DO Affect the Breath Test
The guidelines are explicit about which medications interfere with H. pylori testing accuracy:
Proton pump inhibitors (PPIs) should be stopped for at least 2 weeks (ideally 7-14 days) before urea breath testing, as they cause 10-40% false-negative rates by decreasing bacterial load in the stomach 1
Antibiotics and bismuth must be withheld for at least 4 weeks before testing to avoid false-negative results 1, 2
H2-receptor antagonists may cause some false-negatives but to a much lesser extent than PPIs, and guidelines did not find it necessary to stop them when using citric acid test meals 1
Why Reglan Is Not Listed as Interfering
The comprehensive Maastricht IV/Florence Consensus guidelines 1 and the ACCF/ACG/AHA expert consensus 1 systematically reviewed medications that affect H. pylori testing accuracy. Metoclopramide (Reglan) is notably absent from these lists.
The mechanism by which medications interfere with breath testing involves:
- Increasing gastric pH (PPIs, H2-blockers) which decreases bacterial load 1
- Direct antimicrobial effects (antibiotics, bismuth) 1, 2
Reglan works as a prokinetic agent that accelerates gastric emptying - it does not alter gastric pH or have antimicrobial properties 3
Test Meal Considerations
Interestingly, research specifically examined whether delaying gastric emptying (the opposite of what Reglan does) affects breath test performance:
- A study using L-DOPA to pharmacologically delay gastric emptying found no modification of either sensitivity or specificity of the urea breath test 3
- This suggests gastric motility changes do not significantly impact test accuracy 3
Clinical Bottom Line
Continue Reglan without interruption when ordering an H. pylori breath test. Focus your attention on ensuring the patient has discontinued: