Amoxicillin 250 mg BID for 10 Days is Insufficient for Streptococcal Pharyngitis
The recommended dose of amoxicillin for streptococcal pharyngitis is 50 mg/kg once daily (maximum 1,000 mg) or 25 mg/kg twice daily (maximum 500 mg per dose) for 10 days—not 250 mg twice daily. 1
Why 250 mg BID is Inadequate
For children, the standard dosing is 50 mg/kg once daily (maximum 1,000 mg) or 25 mg/kg twice daily (maximum 500 mg per dose), which for most children significantly exceeds 250 mg per dose 1
For adolescents and adults, the recommended dose is 500 mg twice daily for 10 days, which is double the proposed 250 mg dose 1
The older 2002 IDSA guidelines listed penicillin V at 250 mg BID or TID for children, but amoxicillin dosing has evolved based on newer evidence supporting higher doses for optimal bacterial eradication 2
Correct Dosing Regimen
Children: Amoxicillin 50 mg/kg once daily (maximum 1,000 mg) OR 25 mg/kg twice daily (maximum 500 mg per dose) for 10 days 1
Adolescents and adults: Amoxicillin 500 mg twice daily for 10 days 1
Duration: A full 10-day course is essential to prevent acute rheumatic fever, even if symptoms resolve earlier 1
Evidence Supporting Higher Doses
The American Heart Association has endorsed once-daily amoxicillin dosing at the higher dose (50 mg/kg, maximum 1,000 mg) for treatment of streptococcal pharyngitis 1
Once-daily amoxicillin at 750-1,000 mg has been proven non-inferior to twice-daily dosing in a large controlled trial, with bacteriologic failure rates of 20.1% at 14-21 days and only 2.8% at 28-35 days 3
Amoxicillin remains a first-line option due to its proven efficacy, safety, narrow spectrum, and low cost when dosed appropriately 1
Critical Pitfall to Avoid
Underdosing amoxicillin increases the risk of treatment failure and inadequate bacterial eradication, which can lead to complications including acute rheumatic fever 1
The 250 mg BID regimen represents approximately half the recommended dose for most patients and should not be used 1
Alternative if Correct Dosing Cannot Be Used
If there are concerns about tolerability of higher doses, consider intramuscular benzathine penicillin G (1.2 × 10⁶ units as a single dose) for patients who may not complete oral therapy 4
For penicillin-allergic patients with non-immediate reactions, first-generation cephalosporins such as cephalexin 20 mg/kg twice daily (maximum 500 mg per dose) for 10 days are preferred 5