Amoxicillin Dosing for Strep Throat Treatment
For strep throat treatment, amoxicillin should be dosed at 50 mg/kg once daily (maximum 1000 mg) or alternatively 25 mg/kg twice daily (maximum 500 mg per dose) for a full 10-day course. 1, 2
Dosing Regimens for Amoxicillin in Strep Throat
Children:
- Once-daily regimen: 50 mg/kg once daily (maximum 1000 mg)
- Twice-daily regimen: 25 mg/kg twice daily (maximum 500 mg per dose)
- Duration: Full 10-day course is required
Adults and Adolescents:
- Once-daily regimen: 1000 mg once daily
- Twice-daily regimen: 500 mg twice daily
- Duration: Full 10-day course is required
Importance of Complete Treatment Course
A full 10-day course of amoxicillin is critical for:
- Prevention of acute rheumatic fever
- Complete eradication of Group A Streptococcus
- Reduction of symptom duration
- Prevention of complications
Even if symptoms resolve within 24-48 hours after starting treatment, the full 10-day course must be completed 1, 2, 3.
Evidence Supporting Once-Daily Dosing
Research has demonstrated that once-daily amoxicillin (50 mg/kg/day) is as effective as multiple daily doses for treating strep throat:
- A study comparing once-daily amoxicillin to penicillin V given three times daily showed equivalent bacteriologic cure rates, with amoxicillin having a 5% failure rate compared to 11% with penicillin V 4
- A more recent study using PCR to measure bacterial load found no statistical difference between once-daily, twice-daily, and three-times-daily amoxicillin regimens in eradicating Group A Streptococcus 5
Administration Guidelines
- Amoxicillin should be taken at the start of a meal to minimize gastrointestinal intolerance 3
- For oral suspension, shake well before using and refrigerate (though not required) 3
- Patients are considered non-contagious after 24 hours of antibiotic therapy 1, 2
Special Considerations
Renal Impairment
For patients with renal impairment:
- GFR 10-30 mL/min: 250-500 mg every 12 hours
- GFR <10 mL/min: 250-500 mg every 24 hours
- Hemodialysis: Additional dose during and after dialysis 3
Treatment Failures
If symptoms persist or worsen after 5 days of appropriate treatment, consider:
- Non-compliance with the prescribed regimen
- Penicillin treatment failure
- New infection with Group A Streptococcus
- Viral pharyngitis in a streptococcal carrier 2
Clinical Pearls
- Amoxicillin has largely replaced penicillin V as the oral treatment of choice for strep throat due to better taste (improving adherence), convenient dosing, and excellent efficacy 2
- Once-daily dosing significantly improves compliance compared to multiple daily doses 4
- Group A Streptococcus has never developed resistance to penicillins, making amoxicillin a reliable first-line treatment 2
- Post-treatment throat cultures are not routinely recommended unless symptoms persist 2
By following these dosing guidelines and ensuring completion of the full 10-day course, you can effectively treat strep throat while minimizing complications and improving patient outcomes.