When can I start H pylori treatment after taking Tums (calcium carbonate)?

Timing of H. pylori Testing After Tums (Calcium Carbonate)

You must wait at least 2 weeks after stopping Tums (calcium carbonate) before performing H. pylori testing, as antacids can cause false-negative results on both urea breath tests and stool antigen tests. 1, 2

Critical Testing Requirements

Medication Discontinuation Before Testing

• Stop all antacids (including Tums/calcium carbonate) for at least 2 weeks before performing urea breath test or stool antigen testing 1, 2
• Stop PPIs for at least 2 weeks before testing, as these also interfere with test accuracy 1, 2, 3
• Stop antibiotics and bismuth for at least 4 weeks before testing 1

The mechanism is straightforward: antacids like Tums reduce gastric acidity and can temporarily suppress H. pylori bacterial load, leading to false-negative test results even when infection is present. This is why the 2-week washout period is mandatory.

Optimal Timing for Test of Cure

• Perform test of cure at least 4 weeks after completing H. pylori treatment 4, 1, 2
• Ensure the patient has been off PPIs for at least 2 weeks and off antacids for at least 2 weeks before testing 1, 2
• Use either urea breath test or validated monoclonal stool antigen test—never use serology for confirmation of eradication, as antibodies persist long after successful treatment 1, 2

Common Pitfalls to Avoid

• Do not test while the patient is taking any acid-suppressing medications (PPIs, H2 blockers, or antacids like Tums), as this dramatically increases false-negative rates 1, 2
• Do not assume a negative test is accurate if the patient has not completed the full 2-week washout period from antacids 1, 2
• If the patient requires symptom control during the washout period, consider short-term use of sucralfate, which does not interfere with H. pylori testing 1

Treatment Considerations After Diagnosis

Once H. pylori is confirmed (after appropriate medication washout):

• Bismuth quadruple therapy for 14 days is the preferred first-line treatment, consisting of PPI twice daily, bismuth 300mg four times daily, metronidazole 500mg three times daily, and tetracycline 500mg four times daily 1, 5, 2
• High-dose PPI twice daily (taken 30 minutes before meals) is mandatory to maximize treatment efficacy 1, 5, 2
• 14-day treatment duration is superior to shorter regimens, improving eradication by approximately 5% 4, 1, 3