Amoxicillin Dosing Intervals
Amoxicillin should be taken every 8 hours (three times daily) or every 12 hours (twice daily), depending on the infection severity and patient age. 1
Standard Dosing Schedules
For Adults and Children ≥3 Months and ≥40 kg
Mild to moderate infections (ear/nose/throat, skin, genitourinary):
- 500 mg every 12 hours, OR
- 250 mg every 8 hours 1
Severe infections or lower respiratory tract infections:
- 875 mg every 12 hours, OR
- 500 mg every 8 hours 1
For Children ≥3 Months and <40 kg
Mild to moderate infections:
- 25 mg/kg/day divided every 12 hours, OR
- 20 mg/kg/day divided every 8 hours 1
Severe infections or lower respiratory tract infections:
- 45 mg/kg/day divided every 12 hours, OR
- 40 mg/kg/day divided every 8 hours 1
For Infants <3 Months
- Maximum 30 mg/kg/day divided every 12 hours 1
Specific Clinical Contexts
Community-Acquired Pneumonia (Pediatric)
- Preferred: 50-75 mg/kg/day in 2 doses 2
- This twice-daily regimen is supported by research showing equivalent efficacy to three-times-daily dosing 3, 4
H. pylori Infection (Adults Only)
- Triple therapy: 1 gram every 12 hours for 14 days
- Dual therapy: 1 gram every 8 hours for 14 days 1
Animal/Human Bites
- 875/125 mg (amoxicillin-clavulanate) twice daily 5
Streptococcal Pharyngitis
- Children: 250 mg twice daily or three times daily
- Adolescents/Adults: 250 mg four times daily OR 500 mg twice daily 6
Key Timing Considerations
Take at the start of meals to minimize gastrointestinal intolerance 1. This is the single most important administration instruction from the FDA label.
Twice-daily vs. three-times-daily dosing: Research demonstrates that twice-daily regimens improve compliance without sacrificing efficacy 3, 4, 7. The 12-hour interval is easier for families to maintain, with fewer missed doses and better adherence to the dosing schedule 4, 7.
Avoid prolonged interdose intervals: Studies show that with three-times-daily regimens, patients often extend the overnight interval to >13 hours, creating subtherapeutic drug levels 7. The twice-daily regimen naturally prevents this problem.
Renal Impairment Adjustments
For patients with severe renal impairment:
- 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 1
Duration Considerations
Continue treatment for minimum 48-72 hours beyond symptom resolution or bacterial eradication 1. For Streptococcus pyogenes infections, treat for at least 10 days to prevent acute rheumatic fever 1.