Amoxicillin Dosing for Strep Throat in an 11-Year-Old Patient
For an 11-year-old patient weighing 53.98 kg with strep throat, the recommended dose is 1000 mg of amoxicillin twice daily for 10 days.
Weight-Based Dosing Algorithm
Since this patient weighs more than 40 kg, adult dosing applies rather than pediatric weight-based calculations 1, 2.
- For patients ≥40 kg with Group A Streptococcal pharyngitis: The standard adult dose is 500 mg every 12 hours or 250 mg every 8 hours for mild to moderate infections 2.
- However, for strep throat specifically: The Infectious Diseases Society of America recommends 50-75 mg/kg/day divided into 2 doses, with a maximum of 1000 mg per dose 1.
Recommended Regimen
The optimal dosing for this patient is:
- 1000 mg twice daily (every 12 hours) for 10 days 1
- This provides approximately 37 mg/kg/day, which falls within the recommended 50-75 mg/kg/day range while respecting the 1000 mg maximum per dose 1
- The twice-daily dosing has been proven as efficacious as more frequent dosing and improves adherence 1, 3
Treatment Duration
- The treatment course must be 10 days to prevent acute rheumatic fever, regardless of symptom resolution 2, 1
- Patients become non-contagious after 24 hours of antibiotic therapy 1
- Clinical improvement should be evident within 48-72 hours 1
Administration Instructions
- Amoxicillin should be taken at the start of a meal to minimize gastrointestinal intolerance 2
- The full 10-day course must be completed even if symptoms resolve earlier 2
Alternative Considerations
- If the patient has risk factors for resistant organisms (recent antibiotic use, high local resistance rates), some clinicians may consider higher dosing, though this is not standard for uncomplicated strep throat 1
- For penicillin allergy: Clindamycin 10-20 mg/kg/day divided into 3 doses would be an appropriate alternative 1, 4
Common Pitfall to Avoid
Do not use once-daily dosing of penicillin or amoxicillin for strep throat, as it is associated with a 12 percentage point lower cure rate compared to twice-daily dosing 3. The twice-daily regimen is both more effective and easier for compliance 1, 3.