What is the recommended dose of amoxicillin (amoxicillin) for strep throat?

Amoxicillin Dosage for Strep Throat

For strep throat (Group A Streptococcal pharyngitis), the recommended dose of amoxicillin is 50 mg/kg once daily (maximum 1,000 mg) or 25 mg/kg twice daily (maximum 500 mg per dose) for children, and 500 mg twice daily for adolescents and adults, with all regimens continuing for a full 10 days. 1

Dosing Recommendations by Age Group

• Children:

  • 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

• Adolescents and Adults:

  • 500 mg twice daily for 10 days 1, 2

Important Clinical Considerations

• A full 10-day course is essential to prevent acute rheumatic fever, even if symptoms resolve earlier 1, 3
• Treatment should begin promptly after diagnosis to reduce contagiousness and morbidity 2
• Patients are generally considered non-contagious after 24 hours of antibiotic therapy 2, 1
• Taking amoxicillin at the start of a meal can minimize gastrointestinal intolerance 3

Evidence Supporting Once-Daily Dosing

• Once-daily amoxicillin (50 mg/kg, maximum 1,000 mg) has been shown to be as effective as multiple daily doses 2, 4
• The once-daily regimen may improve adherence compared to multiple daily doses 1, 5
• A meta-analysis found that once-daily amoxicillin is not inferior to other dosing schedules of amoxicillin or penicillin V 5

Alternative Regimens for Penicillin-Allergic Patients

• For mild penicillin allergy (non-anaphylactic):

  • Cephalexin: 20 mg/kg twice daily (maximum 500 mg per dose) for 10 days 1

• For severe penicillin allergy:

  • Clindamycin: 7 mg/kg three times daily (maximum 300 mg per dose) for 10 days 1, 6
  • Azithromycin: 12 mg/kg once daily (maximum 500 mg) for 5 days, though macrolide resistance should be considered 1, 6

Special Situations

• For recurrent streptococcal pharyngitis or treatment failures:
  • Amoxicillin/clavulanate: 40 mg/kg/day of amoxicillin component in three divided doses for 10 days 2, 1
  • Clindamycin: 20-30 mg/kg/day in 2-4 divided doses for 10 days (adults: 600 mg/day) 2

Dosage Adjustments for Renal Impairment

• For patients with severe renal impairment (GFR 10-30 mL/min):
  • 500 mg or 250 mg every 12 hours, depending on infection severity 3
• For patients with very severe renal impairment (GFR <10 mL/min):
  • 500 mg or 250 mg every 24 hours, depending on infection severity 3

Common Pitfalls to Avoid

• Stopping treatment early when symptoms improve (must complete full 10-day course) 1, 3
• Inadequate dosing that may fail to eradicate the organism, particularly during viral co-infection 7
• Using shortened treatment courses (5-7 days), which although some studies suggest may be effective 8, are not yet recommended by current guidelines 1, 3