Amoxicillin Dosing for Bacterial Tonsillitis in an 11-Year-Old
For an 11-year-old female weighing 39.6 kg with bacterial tonsillitis, the recommended daily dose of amoxicillin is 45 mg/kg/day divided into two doses, which equals approximately 900 mg per day (450 mg twice daily).
Dosage Calculation
The FDA-approved dosing for amoxicillin in pediatric patients with respiratory tract infections is as follows:
- For children weighing less than 40 kg with moderate to severe infections (including tonsillitis): 45 mg/kg/day divided into two doses every 12 hours 1
- Calculation for this patient: 39.6 kg × 45 mg/kg/day = 1,782 mg/day
- Rounded to a practical dose: 900 mg daily (450 mg twice daily)
Treatment Duration
- Treatment should continue for a minimum of 10 days for any infection caused by Streptococcus pyogenes (the most common cause of bacterial tonsillitis) to prevent acute rheumatic fever 1
- Treatment should be continued for at least 48-72 hours beyond the time the patient becomes asymptomatic 1
Administration Guidelines
- Amoxicillin should be taken at the start of a meal to minimize gastrointestinal intolerance 1
- For oral suspension, ensure proper reconstitution and shaking before administration 1
Alternative Options
If the patient has a penicillin allergy or other contraindications to amoxicillin:
- For non-severe penicillin allergy: Consider cephalexin 25 mg/kg/day in 4 divided doses 2
- For immediate hypersensitivity reactions: Consider clindamycin 10-20 mg/kg/day in 3 divided doses 2
Monitoring and Follow-up
- Assess clinical response within 48-72 hours of treatment initiation
- Look for decreased fever, improved respiratory symptoms, and decreased throat pain
- If no improvement after 48-72 hours, consider alternative antibiotics or reevaluation
Important Considerations
- Compliance with the full 10-day course is essential to prevent treatment failure and complications 3
- Bacteriologic failure rates with penicillin therapy for streptococcal pharyngitis have increased over time, potentially due to poor compliance 3
- Ensure adequate hydration and consider antipyretics for symptomatic relief
This dosing recommendation aligns with the FDA-approved dosing guidelines for amoxicillin in pediatric patients with respiratory tract infections, providing optimal coverage for the most common bacterial pathogens in tonsillitis while minimizing the risk of treatment failure.