Recommended Dosage of Amoxicillin for Streptococcal Pharyngitis
For patients without penicillin allergy, amoxicillin should be administered at 50 mg/kg once daily (maximum = 1,000 mg) or alternatively 25 mg/kg twice daily (maximum = 500 mg per dose) for 10 days to treat streptococcal pharyngitis. 1
First-line Treatment Options
Amoxicillin Regimen
- Amoxicillin 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
- This regimen has strong recommendation with high-quality evidence 1
Other First-line Options (for patients without penicillin allergy)
- Penicillin V (oral): Children - 250 mg two or three times daily; Adolescents and adults - 250 mg four times daily or 500 mg twice daily for 10 days 1
- Penicillin G benzathine (intramuscular): <27 kg: 600,000 U; ≥27 kg: 1,200,000 U as a single dose 1
Treatment for Penicillin-Allergic Patients
- Cephalexin (Keflex): 20 mg/kg per dose twice daily (maximum = 500 mg per dose) for 10 days 1
- Cefadroxil: 30 mg/kg once daily (maximum = 1 g) for 10 days 1
- Clindamycin: 7 mg/kg per dose three times daily (maximum = 300 mg per dose) for 10 days 1
- Azithromycin: 12 mg/kg once daily (maximum = 500 mg) for 5 days 1
- Clarithromycin: 7.5 mg/kg per dose twice daily (maximum = 250 mg per dose) for 10 days 1
Clinical Considerations
- The 10-day duration is critical for preventing acute rheumatic fever, a serious non-suppurative complication 1
- Once-daily dosing of amoxicillin has been shown to be as effective as twice-daily dosing, which may improve patient adherence 2, 3
- A meta-analysis has confirmed that twice-daily dosing of penicillin is as efficacious as more frequent dosing regimens, but once-daily penicillin (unlike once-daily amoxicillin) is associated with decreased efficacy 4
Important Caveats
- Macrolides (azithromycin, clarithromycin) may have resistance issues that vary geographically and temporally 1, 5
- Cephalosporins should be avoided in patients with immediate-type hypersensitivity to penicillin 1
- Treatment can be safely postponed for up to 9 days after symptom onset and still prevent acute rheumatic fever 1
- Follow-up post-treatment testing is not routinely recommended but may be considered in special circumstances 1
- Testing and treatment are generally not recommended for children under 3 years of age unless they have specific risk factors (e.g., older sibling with GAS infection) 1
Treatment for Chronic Carriers
- For recurrent streptococcal pharyngitis or chronic carriers, different regimens may be needed 1
- Options include clindamycin (20-30 mg/kg/day in three doses), amoxicillin/clavulanate (40 mg amoxicillin/kg/day in three doses), or combination therapy with penicillin and rifampin 1
The evidence strongly supports a 10-day course of amoxicillin as a first-line treatment for streptococcal pharyngitis, with once-daily dosing being as effective as multiple daily doses, potentially improving adherence and treatment outcomes 1, 2, 3.