Amoxicillin Dosage for Strep Throat in a 20 kg Child
For a child weighing 20 kg with streptococcal pharyngitis (strep throat), the recommended dose of amoxicillin is 50 mg/kg/day once daily (1000 mg total daily dose) or alternatively 25 mg/kg/day twice daily (500 mg per day in two divided doses) for 10 days. 1
Dosing Options
Based on the child's weight of 20 kg, the specific dosing would be:
- Once-daily regimen: 20 kg × 50 mg/kg = 1000 mg (maximum) once daily
- Twice-daily regimen: 20 kg × 25 mg/kg = 500 mg per day (250 mg twice daily)
Treatment Duration
- Treatment must continue for a full 10 days, even if symptoms improve earlier 1
- A minimum of 10 days of treatment is specifically recommended for any infection caused by Streptococcus pyogenes to prevent acute rheumatic fever 2
Evidence Strength
The recommendation for amoxicillin at this dosage carries a "Strong, high" evidence rating according to the Infectious Diseases Society of America (IDSA) guidelines 1. This makes it one of the most strongly supported treatment options for strep throat in children.
Clinical Considerations
- Amoxicillin should be taken at the start of a meal to minimize gastrointestinal intolerance 2
- Once-daily dosing has been shown to be as effective as twice-daily dosing, which may improve adherence 3, 4
- For children who cannot swallow tablets, oral suspension formulations are available and should be shaken well before use 2
Alternatives for Penicillin Allergy
If the child has a penicillin allergy, alternative treatments include:
- Cephalexin: 20 mg/kg twice daily (maximum 500 mg per dose)
- Cefadroxil: 30 mg/kg once daily (maximum 1 g)
- Clindamycin: 7 mg/kg three times daily (maximum 300 mg per dose)
- Azithromycin: 12 mg/kg once daily (maximum 500 mg) for 5 days 1
Common Pitfalls to Avoid
- Insufficient duration: Stopping treatment early even if symptoms resolve can lead to treatment failure and complications like rheumatic fever
- Incorrect dosing: Underdosing may lead to treatment failure while overdosing increases risk of side effects
- Not considering local resistance patterns: In areas with high macrolide resistance, azithromycin should not be used as first-line therapy
- Failing to ensure adherence: The full 10-day course must be completed for optimal outcomes
Remember that amoxicillin is preferred over penicillin V for children due to better taste, which improves compliance, and its proven efficacy with convenient once or twice daily dosing.