Amoxicillin Dosing for Strep Throat in a 7-Year-Old
For a 7-year-old child weighing 28.94 kg with strep throat, give amoxicillin 50 mg/kg/day once daily (approximately 1450 mg once daily, rounded to 1500 mg) OR 25 mg/kg twice daily (approximately 725 mg twice daily, rounded to 750 mg) for 10 days. 1, 2
Recommended Dosing Regimens
Based on the 2012 IDSA guidelines for Group A Streptococcal pharyngitis and FDA labeling, you have two equally effective options 1, 2:
Option 1: Once-Daily Dosing (Preferred for Compliance)
- 50 mg/kg once daily (maximum 1000 mg per FDA label, though this child's calculated dose of 1447 mg exceeds this)
- For this 28.94 kg child: approximately 1450 mg once daily
- Duration: 10 days
Option 2: Twice-Daily Dosing
- 25 mg/kg twice daily (maximum 500 mg per dose)
- For this 28.94 kg child: approximately 725 mg twice daily
- Duration: 10 days
Practical Prescribing
The FDA-approved dosing from the drug label states 50 mg/kg/day once daily with a maximum of 1000 mg, OR 25 mg/kg twice daily. 2 Given this child's weight would calculate to 1447 mg once daily, you should either:
- Use 1000 mg once daily (adhering to FDA maximum), or
- Use 750 mg twice daily (25 mg/kg × 28.94 kg ÷ 2 = 723.5 mg, rounded to 750 mg)
The twice-daily regimen may be more appropriate here as it avoids exceeding the FDA maximum while still providing adequate dosing.
Key Clinical Points
The 10-day duration is mandatory to prevent acute rheumatic fever, regardless of which dosing regimen you choose 1, 2. This is explicitly stated in both the IDSA guidelines and FDA labeling.
Once-daily dosing has strong evidence support. Recent research demonstrates that once-daily amoxicillin achieves 91% bacterial eradication by the next morning and is non-inferior to multiple daily dosing for Group A Streptococcus 3, 4. The IDSA guidelines give once-daily amoxicillin a "strong recommendation with high-quality evidence" 1.
Administration Instructions
- Give at the start of a meal to minimize GI upset 2
- Shake liquid suspension well before each dose 2
- Use a calibrated oral syringe for accurate dosing 2
- Refrigeration is preferable but not required 2
- Discard unused suspension after 14 days 2
Common Pitfall
Do not underdose larger children. Recent data shows that children over 60 kg frequently receive less than 40 mg/kg/day because clinicians are reluctant to exceed "adult doses" 5. This child at 28.94 kg should receive the full weight-based dose. The adult dose of 500 mg twice daily would only provide 34.5 mg/kg/day for this child—inadequate for strep pharyngitis.