Pediatric Amoxicillin Dosing
For most common pediatric infections, use amoxicillin 45-50 mg/kg/day divided twice daily (every 12 hours) for children ≥3 months old, with higher doses of 80-90 mg/kg/day reserved for pneumonia, severe infections, or drug-resistant Streptococcus pneumoniae. 1
Standard Dosing by Infection Type
Mild to Moderate Infections (Ear/Nose/Throat, Skin, Genitourinary)
- Children ≥3 months and <40 kg: 25 mg/kg/day divided every 12 hours OR 20 mg/kg/day divided every 8 hours 1
- Children ≥40 kg and adults: 500 mg every 12 hours OR 250 mg every 8 hours 1
Severe Infections or Lower Respiratory Tract Infections
- Children ≥3 months and <40 kg: 45 mg/kg/day divided every 12 hours OR 40 mg/kg/day divided every 8 hours 1
- Children ≥40 kg and adults: 875 mg every 12 hours OR 500 mg every 8 hours 1
Specific Pathogen-Based Dosing (from PIDS/IDSA Guidelines)
Streptococcus pneumoniae (penicillin-susceptible):
Group A Streptococcus:
- Oral: 50-75 mg/kg/day in 2 doses 2
Haemophilus influenzae (β-lactamase negative):
Haemophilus influenzae (β-lactamase producing):
- Switch to amoxicillin-clavulanate: 45 mg/kg/day in 3 doses OR 90 mg/kg/day in 2 doses (amoxicillin component) 3, 2
Age-Specific Considerations
Infants <3 Months (Neonates)
Maximum dose: 30 mg/kg/day divided every 12 hours due to immature renal function 1
Children ≥3 Months
Use weight-based dosing as outlined above. The FDA label and clinical guidelines consistently support twice-daily dosing for most infections, which improves compliance without compromising efficacy 1, 4, 5.
Duration of Therapy
- Streptococcus pyogenes (Group A Strep): Minimum 10 days to prevent acute rheumatic fever 1
- Most other infections: Continue 48-72 hours beyond symptom resolution or bacterial eradication 1
- Community-acquired pneumonia: Recent evidence suggests 3 days may be noninferior to 7 days in uncomplicated cases, though 7 days remains standard 6
Critical Dosing Pitfalls
Weight-based dosing errors in obese children: When calculated doses exceed standard adult doses (1500 mg/day), prescribing patterns vary widely. The FDA label does not specify a maximum dose cap, but clinical judgment is needed 7. For children requiring >1500 mg/day based on weight, consider:
- Using the calculated weight-based dose for severe infections
- Capping at adult dose (1500 mg/day) for mild-moderate infections
- Ensuring adequate follow-up
Twice vs. three times daily: Both regimens are equally effective for the same total daily dose 4, 5. Twice-daily dosing improves compliance and should be preferred for most outpatient infections.
High-dose amoxicillin (80-90 mg/kg/day): Reserve for:
- Pneumococcal infections in areas with penicillin resistance
- Community-acquired pneumonia
- Severe infections
- Recent antibiotic exposure (within 30 days)
Renal Impairment Dosing
For children ≥3 months and >40 kg:
- 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
Practical Prescribing
Always specify on the prescription:
- Total daily dose in mg/kg/day
- Number of divided doses per day
- Duration of therapy
- Indication for treatment
- Child's weight 8
Administration: Give at the start of meals to minimize gastrointestinal intolerance 1. Oral suspension can be mixed with formula, milk, juice, or water if needed, but must be taken immediately after mixing 1.