Amoxicillin Dosing for Pediatric Streptococcal Pharyngitis
For a child with strep throat and no penicillin allergy, prescribe amoxicillin 50 mg/kg once daily (maximum 1000 mg) or 25 mg/kg twice daily (maximum 500 mg per dose) for a full 10 days. 1
Weight-Based Dosing Regimen
The Infectious Diseases Society of America recommends amoxicillin at 50 mg/kg once daily (maximum 1000 mg) or alternatively 25 mg/kg twice daily (maximum 500 mg per dose) for 10 days as first-line therapy for children with Group A streptococcal pharyngitis. 1
The FDA label confirms that for ear/nose/throat infections including strep pharyngitis, children weighing less than 40 kg should receive 25 mg/kg/day divided every 12 hours (mild/moderate) or 45 mg/kg/day divided every 12 hours (severe infections). 2
Once-daily dosing at 50 mg/kg is equally effective as twice-daily dosing and may improve adherence, with multiple studies demonstrating non-inferiority for bacterial eradication. 3, 4, 5
Why Amoxicillin is Preferred Over Penicillin V
Amoxicillin is the drug of choice for children due to better palatability, availability as a liquid suspension, and identical efficacy to penicillin V, making it easier to administer to younger patients. 6
Amoxicillin at 40-50 mg/kg/day demonstrates significantly superior clinical cure (87.9% vs 70.9%) and bacteriologic cure (79.3% vs 54.5%) compared to conventional lower-dose penicillin V therapy. 7
No documented penicillin resistance in Group A Streptococcus exists anywhere in the world, ensuring reliable efficacy. 1
Critical Treatment Duration Requirement
A full 10-day course is mandatory to achieve maximal pharyngeal eradication of Group A Streptococcus and prevent acute rheumatic fever, even if symptoms resolve within 3-4 days. 1, 2
The FDA label explicitly states: "It is recommended that there be at least 10 days' treatment for any infection caused by Streptococcus pyogenes to prevent the occurrence of acute rheumatic fever." 2
Shortening the course by even a few days results in appreciable increases in treatment failure rates and rheumatic fever risk. 1
Practical Administration Tips
Amoxicillin should be taken at the start of a meal to minimize gastrointestinal intolerance. 2
For oral suspension, the required amount can be placed directly on the child's tongue or mixed with formula, milk, fruit juice, water, or cold drinks, which should then be taken immediately. 2
The child becomes non-contagious after 24 hours of antibiotic therapy. 8
Common Pitfalls to Avoid
Do not prescribe shorter courses than 10 days – therapy can be safely postponed up to 9 days after symptom onset and still prevent rheumatic fever, but once started, the full 10 days must be completed. 6
Do not underdose – ensure the full 50 mg/kg once daily or 25 mg/kg twice daily is prescribed, as lower doses compromise treatment effectiveness and may explain perceived declining penicillin effectiveness. 7, 6
Do not use amoxicillin-clavulanate (Augmentin) for acute pharyngitis – the addition of clavulanate provides no benefit since Group A Streptococcus does not produce beta-lactamase, and it unnecessarily broadens the antimicrobial spectrum. 9