Amoxil (Amoxicillin) Dosing Instructions
For adults with mild to moderate infections, prescribe amoxicillin 500 mg every 12 hours or 250 mg every 8 hours; for severe infections, prescribe 875 mg every 12 hours or 500 mg every 8 hours. 1
Adult Dosing
Standard dosing for respiratory tract and skin infections:
- Mild/Moderate infections: 500 mg every 12 hours OR 250 mg every 8 hours
- Severe infections: 875 mg every 12 hours OR 500 mg every 8 hours 1
Genitourinary tract infections:
- Same dosing as above (mild/moderate vs severe) 1
Special indications:
- Acute uncomplicated gonorrhea: 3 grams as single oral dose 1
- H. pylori eradication (triple therapy): 1 gram twice daily for 14 days (with clarithromycin and lansoprazole) 1
- Lyme disease: 500 mg three times daily for 14-21 days 2
- Strep pharyngitis: 500 mg twice daily for 10 days 3
Pediatric Dosing (>3 months)
Weight-based dosing is essential for children <40 kg:
- Mild/Moderate infections: 25 mg/kg/day divided every 12 hours OR 20 mg/kg/day divided every 8 hours
- Severe infections: 45 mg/kg/day divided every 12 hours OR 40 mg/kg/day divided every 8 hours 1
Children ≥40 kg should receive adult dosing 1
Specific pediatric indications:
- Acute otitis media: 40 mg/kg twice daily for 5 days 4 or 80-90 mg/kg/day for high-dose therapy 5
- Strep pharyngitis: 50 mg/kg once daily (max 1000 mg) for 10 days 3
- Community-acquired pneumonia: 50-75 mg/kg/day in 2 doses 6
Neonatal Dosing (≤12 weeks/≤3 months)
Maximum dose is 30 mg/kg/day divided every 12 hours due to immature renal function 1. Recent evidence suggests 50 mg/kg/day divided twice daily may be optimal for neonatal sepsis, with frequency adjusted by postnatal age 7, 8.
Renal Impairment Adjustments
Dose reduction required only for severe 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
Administration Instructions
Oral suspension may be given without regard to meals (though 400 mg suspension studied only with light meals) 1. After reconstitution, suspension remains stable for 14 days; refrigeration preferred but not required 1.
For children, place suspension directly on tongue or mix with formula, milk, juice, water, or cold drinks—consume immediately and entirely to ensure full dose 1.
Duration of Therapy
Continue treatment 48-72 hours beyond symptom resolution or bacterial eradication 1. For Streptococcus pyogenes infections, minimum 10 days required to prevent acute rheumatic fever 1.
Critical Prescribing Details
When prescribing for children, always include on the prescription:
- Total daily dose in mg/kg
- Number of divided doses per day
- Duration of therapy
- Indication
- Child's current weight 9
Common Pitfalls
Avoid underdosing in obese children: The 80-90 mg/kg/day recommendation for otitis media often exceeds standard adult doses in heavier children, yet many prescribers inappropriately cap doses at adult levels 5. When calculated pediatric dose exceeds 1500 mg/day, clinical judgment is required—consider prescribing the full weight-based dose for severe infections.
Contraindications: Known hypersensitivity to penicillins, including serious reactions like anaphylaxis or Stevens-Johnson syndrome 10. Avoid in pregnancy only if doxycycline is the alternative; amoxicillin is pregnancy category B and compatible with breastfeeding 10, 2, 10.