Maximum Daily Dosage of Amoxicillin in Adults
For adults with normal renal function and bacterial infections, the maximum daily dosage of amoxicillin is 1750 mg per day, divided into doses every 8 to 12 hours. 1
Standard Dosing Guidelines
The FDA-approved dosing for amoxicillin in adults varies by infection severity 1:
Mild to Moderate Infections
- 500 mg every 12 hours OR 250 mg every 8 hours for ear/nose/throat, skin/skin structure, and genitourinary tract infections 1
- This translates to 1000-1500 mg total daily dose
Severe Infections or Lower Respiratory Tract Infections
- 875 mg every 12 hours OR 500 mg every 8 hours 1
- This translates to 1500-1750 mg total daily dose
- This represents the maximum standard dosing for most bacterial infections 1
Special Dosing Situations
H. pylori Infection (Higher Dosing Exception)
The FDA label specifies higher dosing specifically for H. pylori eradication 1:
- Triple therapy: 1000 mg twice daily (2000 mg/day total) given with clarithromycin and lansoprazole for 14 days 1
- Dual therapy: 1000 mg three times daily (3000 mg/day total) given with lansoprazole for 14 days 1
These H. pylori regimens exceed the standard maximum but are FDA-approved for this specific indication only.
Renal Impairment Adjustments
Critical dosing modifications are required for renal dysfunction 1:
- GFR 10-30 mL/min: Maximum 500 mg or 250 mg every 12 hours (depending on severity) 1
- GFR <10 mL/min: Maximum 500 mg or 250 mg every 24 hours 1
- Hemodialysis: 500 mg or 250 mg every 24 hours, with additional dose during and after dialysis 1
- Patients with GFR <30 mL/min should NOT receive the 875 mg dose 1
The serum half-life of amoxicillin increases dramatically with renal impairment, from approximately 71 minutes with normal function to 16 hours in anephric patients 2, 3
Important Clinical Considerations
Administration
- Take at the start of meals to minimize gastrointestinal intolerance 1
- Continue therapy for minimum 48-72 hours beyond symptom resolution or bacterial eradication 1
Duration Caveats
- Streptococcus pyogenes infections require minimum 10 days of treatment to prevent acute rheumatic fever 1
- Some infections may require several weeks of therapy with extended follow-up 1
Common Pitfall
Do not confuse amoxicillin with amoxicillin-clavulanate dosing. Research suggests that for severe Enterobacteriaceae infections, amoxicillin-clavulanate may require dosing up to 6 times daily to achieve pharmacodynamic targets 4, but this does not apply to amoxicillin monotherapy, which has a defined maximum of 1750 mg/day for standard infections 1