Maximum Amoxicillin Dose for Streptococcal Pharyngitis in Children
For Group A streptococcal pharyngitis, the maximum single dose of amoxicillin is 1,000 mg, regardless of the child's weight. 1
Standard Dosing Regimen
Amoxicillin is the preferred first-line antibiotic for strep throat in children, with two equally effective dosing options: 1
- 50 mg/kg once daily (maximum 1,000 mg) for 10 days 1
- Alternative: 25 mg/kg twice daily (maximum 500 mg per dose) for 10 days 1
Both regimens carry a strong recommendation with high-quality evidence from the Infectious Diseases Society of America (IDSA). 1
Weight-Based Calculation
To calculate the appropriate dose for a child:
- Multiply the child's weight in kg by 50 mg/kg for once-daily dosing 1
- If the calculated dose exceeds 1,000 mg, cap it at 1,000 mg 1, 2
- For twice-daily dosing, multiply weight by 25 mg/kg per dose (maximum 500 mg per dose) 1
For example, a child weighing 25 kg would receive:
- Once-daily: 25 kg × 50 mg/kg = 1,250 mg → capped at 1,000 mg once daily 1
- Twice-daily: 25 kg × 25 mg/kg = 625 mg → capped at 500 mg twice daily 1
Critical Treatment Considerations
Complete the full 10-day course regardless of symptom improvement to prevent acute rheumatic fever, even though fever typically resolves within 3-4 days. 1, 2, 3
Antibiotic therapy may be started up to 9 days after symptom onset and still effectively prevent acute rheumatic fever. 2
The once-daily regimen improves adherence without compromising efficacy, as demonstrated in multiple noninferiority trials. 2, 4, 5
When Standard Amoxicillin Is NOT Appropriate
Do not use plain amoxicillin for: 1, 6, 7
- Treatment failures after initial antibiotic therapy 1, 6, 7
- Chronic Group A Streptococcus carriers who have failed first-line eradication 1, 6, 7
In these scenarios, use amoxicillin/clavulanate (Augmentin) at 40 mg/kg/day of the amoxicillin component divided into three doses (maximum 2,000 mg/day) for 10 days. 1, 6, 7
Penicillin Allergy Alternatives
For non-anaphylactic penicillin allergy: 1, 7
- Cephalexin 20 mg/kg/dose twice daily (maximum 500 mg/dose) for 10 days 1
- Cefadroxil 30 mg/kg once daily (maximum 1 g) for 10 days 1
For Type I (IgE-mediated) penicillin allergy: 1, 7
- Clindamycin 7 mg/kg/dose three times daily (maximum 300 mg/dose) for 10 days 1
- Azithromycin 12 mg/kg once daily (maximum 500 mg) for 5 days (use with caution due to resistance) 1
Common Pitfalls to Avoid
Never prescribe antibiotics based solely on clinical presentation—approximately 70% of sore throats are not streptococcal; confirm with rapid antigen detection test or throat culture. 2
Assess for recent antibiotic use (within 4-6 weeks), as this increases the risk of resistant organisms and may warrant alternative therapy. 6, 7
Evaluate clinical response at 48-72 hours; if no improvement, consider treatment failure and switch to amoxicillin/clavulanate or alternative agents. 6, 7
Consider local macrolide resistance patterns before prescribing azithromycin or clarithromycin, as resistance varies geographically and temporally. 1, 7