Amoxicillin Dosing for Strep Throat
For adults and children over 12 years old with confirmed strep throat and no penicillin allergy, the recommended dose is amoxicillin 500 mg twice daily for 10 days, or alternatively 1000 mg once daily for 10 days. 1
Standard Dosing Regimen
The Infectious Diseases Society of America recommends amoxicillin 500 mg twice daily for 10 days as the standard adult dose, which is equivalent to weight-based pediatric dosing when scaled appropriately. 1
Alternatively, amoxicillin 1000 mg once daily for 10 days is equally effective and may improve compliance. 1
For children weighing ≥40 kg, use adult dosing: 500 mg every 12 hours or 250 mg every 8 hours for mild/moderate infections. 2
Why Amoxicillin Over Penicillin V
Amoxicillin is often preferred over penicillin V for young children due to better palatability of the suspension, though efficacy is equal. 3
Higher-dose amoxicillin (40 mg/kg/day) demonstrates significantly better clinical cure (87.9% vs 70.9%) and bacteriologic cure (79.3% vs 54.5%) compared to standard-dose penicillin V, suggesting that inadequate penicillin dosing may explain perceived declining effectiveness. 4
Critical Treatment Duration
Complete the full 10-day course regardless of symptom improvement to prevent acute rheumatic fever—this is non-negotiable. 1, 2
At least 10 days of treatment is required for any infection caused by Streptococcus pyogenes to prevent acute rheumatic fever. 2
Patients become non-contagious after 24 hours of antibiotic therapy, but treatment must continue for the full 10 days to prevent complications. 1
Shortening the course by even a few days dramatically increases treatment failure rates and rheumatic fever risk. 5
Administration Guidelines
Take amoxicillin at the start of a meal to minimize gastrointestinal intolerance. 2
Plain amoxicillin is first-line for uncomplicated streptococcal pharyngitis; amoxicillin-clavulanate should be reserved for recurrent cases or suspected resistance. 1
Common Pitfalls to Avoid
Do not prescribe shorter courses than 10 days despite rapid symptom resolution—fever and constitutional symptoms disappear spontaneously within 3-4 days even without treatment, but this does not indicate adequate bacterial eradication. 3
Do not use amoxicillin-clavulanate as first-line therapy when plain amoxicillin is appropriate, as this unnecessarily broadens the spectrum and increases cost. 1
Do not stop treatment when the patient feels better—the primary goal is preventing acute rheumatic fever, which requires complete bacterial eradication, not just symptomatic improvement. 5