Amoxicillin Dosing for H. pylori Eradication
For adults without penicillin allergy, use amoxicillin 1 gram twice daily (every 12 hours) for 14 days as part of triple therapy with clarithromycin 500 mg twice daily and a PPI, or 1 gram three times daily (every 8 hours) for 14 days as dual therapy with a PPI. 1
Standard Dosing Regimens for Adults
The FDA-approved dosing provides two options 1:
Triple Therapy (Preferred)
- Amoxicillin 1 gram twice daily (every 12 hours)
- Clarithromycin 500 mg twice daily
- Lansoprazole 30 mg twice daily (or equivalent PPI)
- Duration: 14 days
Dual Therapy (Alternative)
- Amoxicillin 1 gram three times daily (every 8 hours)
- Lansoprazole 30 mg three times daily
- Duration: 14 days
High-Dose Amoxicillin Regimens
Recent evidence supports escalating amoxicillin doses for improved eradication rates. The 2021 AGA guidelines describe high-dose dual therapy as amoxicillin 2-3 grams daily in 3-4 split doses with high-dose PPI twice daily for 14 days 2. This approach is particularly relevant after treatment failures.
For patients with obesity undergoing bariatric surgery, weight-adjusted dosing at 50 mg/kg/day (not exceeding 6 grams/day) achieves significantly higher eradication rates (89.6% vs 68.2%) compared to fixed-dose regimens 3. This represents a fourfold increase in eradication odds without increased adverse events.
Pediatric Dosing
For children, the evidence is limited but suggests:
- Amoxicillin 50 mg/kg/day divided into appropriate doses
- Combined with bismuth or tinidazole for 6 weeks 4
- No established FDA dosing for H. pylori in pediatric patients
Patients with Penicillin Allergy
In patients with true penicillin allergy, amoxicillin is absolutely contraindicated 1. Alternative regimens include:
Bismuth Quadruple Therapy (Most Evidence-Based)
- Bismuth ~300 mg four times daily
- Metronidazole 500 mg three times daily
- Tetracycline 500 mg four times daily
- PPI twice daily
- Duration: 14 days
- Eradication rate: 81.4% (95% CI 78.6%-84.2%) 2, 5
Emerging Alternatives for Penicillin Allergy
Recent studies show promising results with:
- Minocycline-based regimens: 84-91.7% eradication 6
- Cefuroxime-based regimens: 82-90.9% eradication 6
- Tetracycline/vonoprazan dual therapy: 92-95.1% eradication 7
Important caveat: Cefuroxime carries cross-reactivity risk in penicillin-allergic patients (~3% allergy rate) 6. Consider allergy testing before use if the patient has a history of severe penicillin reactions 2.
Renal Impairment Adjustments
For patients with severe renal impairment 1:
- GFR 10-30 mL/min: 500 mg or 250 mg every 12 hours
- GFR <10 mL/min: 500 mg or 250 mg every 24 hours
- Hemodialysis: 500 mg or 250 mg every 24 hours, with additional dose during and after dialysis
Key Administration Points
- Take at the start of meals to minimize gastrointestinal intolerance 1
- PPIs should be dosed 30 minutes before eating on an empty stomach 2
- Treatment duration of 14 days is superior to shorter courses across all regimens 2
Common Pitfalls to Avoid
Underdosing in obesity: Fixed-dose regimens fail more frequently in patients with higher body weight due to increased volume of distribution 3
Assuming penicillin allergy without testing: Up to 95% of patients labeled as penicillin-allergic have negative skin tests 8. Consider allergy testing to expand treatment options.
Using triple therapy in high clarithromycin resistance areas: If local resistance exceeds 15%, bismuth quadruple or concomitant therapy should be first-line 2
Inadequate acid suppression: Standard-dose PPIs may be insufficient; high-dose PPIs or vonoprazan significantly improve amoxicillin-based regimen efficacy 9, 7