Amoxicillin Dosing for Strep Throat in Children
For pediatric strep throat, use amoxicillin 50 mg/kg once daily (maximum 1000 mg) or 25 mg/kg twice daily (maximum 1000 mg per dose) for a full 10-day course. 1
Standard Dosing Algorithm
The American Academy of Pediatrics recommends 50-75 mg/kg/day divided into 2 doses for 10 days, with a maximum of 1000 mg per dose, for Group A Streptococcal pharyngitis. 2
The preferred simplified regimen is 50 mg/kg/day given once daily or 25 mg/kg twice daily, both for 10 days, which provides superior adherence compared to older three-times-daily penicillin regimens. 1
This dosing is significantly more effective than the older 40 mg/kg/day regimen, which should no longer be used. 1
Weight-Based Calculation Examples
For a 20 kg child: 50 mg/kg/day = 1000 mg total daily dose, given as either 1000 mg once daily OR 500 mg twice daily. 2
For a 13.6 kg (30 lb) child: 680 mg once daily OR 340 mg twice daily. 1
For a 44.5 kg child: The calculated dose would be 2225 mg/day, but this must be capped at 1000 mg per dose (2000 mg/day maximum). 2
Critical Treatment Duration
Complete the full 10-day course regardless of symptom improvement to prevent acute rheumatic fever. 1, 2
Children become non-contagious after just 24 hours of appropriate antibiotic therapy and may return to school on day 2 if afebrile and clinically improved. 2
However, the full 10-day course must still be completed despite clinical improvement. 2
Penicillin Allergy Alternatives
For non-anaphylactic penicillin reactions: Use narrow-spectrum cephalosporins such as cephalexin or cefadroxil for 10 days. 2
For Type I hypersensitivity/anaphylaxis: Use clindamycin 10-20 mg/kg/day divided into 3 doses. 2
Macrolides (azithromycin, clarithromycin) have inferior bacteriologic efficacy and should be reserved only for true Type I allergies. 2
Common Pitfalls to Avoid
Do not use the older 40 mg/kg/day dosing regimen - current evidence supports 50 mg/kg/day for optimal eradication. 1
Never exceed 1000 mg per dose even in larger children or adolescents. 2
Do not stop treatment early when symptoms improve - premature discontinuation is the most common cause of treatment failure and increases rheumatic fever risk. 2
Ensure dosing is based on actual body weight, not age alone. 2
Evidence Supporting Once-Daily Dosing
Once-daily amoxicillin at 50 mg/kg has been shown to be non-inferior to twice-daily penicillin V for GABHS eradication, with treatment failure rates of only 5.8% at early follow-up. 3
The once-daily regimen significantly improves adherence, with reported adherence rates of 90%. 2
Real-time PCR studies demonstrate that once-daily dosing achieves bacterial load reduction equivalent to multiple-daily dosing regimens. 4