Amoxicillin Dosing for Strep Throat in Pediatric Patients
For pediatric patients with strep throat (Group A streptococcal pharyngitis), amoxicillin should be dosed at 50 mg/kg once daily (maximum 1,000 mg) OR 25 mg/kg twice daily (maximum 500 mg per dose) for 10 days. 1
Weight-Based Dosing Algorithm
The IDSA guideline provides clear, weight-based dosing that should be followed for all pediatric patients:
- Once-daily regimen: 50 mg/kg/day given as a single dose (maximum 1,000 mg) 1, 2
- Twice-daily regimen: 25 mg/kg/day per dose, given every 12 hours (maximum 500 mg per dose) 1, 2
- Duration: Complete the full 10-day course regardless of symptom resolution to prevent acute rheumatic fever 1, 3
Practical Examples:
- 30-pound (13.6 kg) child: 680 mg once daily OR 340 mg twice daily 2
- 44.5 kg child: Since this exceeds 40 kg, use adult dosing of 500 mg twice daily (not to exceed 1,000 mg per dose for strep throat) 1
Critical Treatment Considerations
Complete the full 10-day course even if the child becomes asymptomatic earlier—this is essential to prevent acute rheumatic fever and other complications. 1, 3 The FDA label explicitly states that at least 10 days of treatment is required for any infection caused by Streptococcus pyogenes. 3
Advantages of Amoxicillin Over Penicillin V
Amoxicillin is preferred over penicillin V for several practical reasons:
- Better palatability: The suspension tastes better, improving adherence in children 1, 2
- Convenient dosing: Twice-daily or once-daily dosing versus penicillin V's three to four times daily 1
- Equal or superior efficacy: Research demonstrates amoxicillin at 40-50 mg/kg/day achieves higher bacteriologic cure rates (79.3%) compared to standard-dose penicillin V (54.5%) 4
Common Pitfall to Avoid
Do not use the older 40 mg/kg/day dosing regimen that appears in some older literature. 2 The current IDSA guideline clearly recommends 50 mg/kg once daily or 25 mg/kg twice daily as the standard of care. 1 The once-daily 50 mg/kg regimen has been validated in multiple studies and provides adequate bacteriologic eradication. 5, 6
Administration Instructions
- Administer at the start of a meal to minimize gastrointestinal intolerance 3
- For oral suspension, shake well before each use 3
- The suspension can be mixed with formula, milk, fruit juice, or water if needed, but must be taken immediately after mixing 3
When to Consider Alternatives
For penicillin-allergic patients:
- Non-immediate hypersensitivity: Cephalexin 20 mg/kg per dose twice daily (maximum 500 mg per dose) for 10 days 1, 7
- Immediate hypersensitivity: Clindamycin 7 mg/kg per dose three times daily (maximum 300 mg per dose) for 10 days OR azithromycin 12 mg/kg once daily (maximum 500 mg) for 5 days 1
Reserve amoxicillin/clavulanate (Augmentin) for treatment failures or chronic carriers who have failed first-line therapy—it is not indicated for initial treatment of uncomplicated strep throat. 1, 2