What is the appropriate Augmentin (amoxicillin‑clavulanate) dose for a 4‑year‑old child weighing 37 lb (≈16.8 kg) with streptococcal pharyngitis?

Augmentin Dosing for Streptococcal Pharyngitis in a 4-Year-Old, 37-Pound Child

For a 4-year-old child weighing 37 pounds (16.8 kg) with streptococcal pharyngitis, Augmentin is NOT the first-line antibiotic—plain amoxicillin should be used instead at 50 mg/kg once daily (840 mg) or 25 mg/kg twice daily (420 mg per dose) for 10 days. 1, 2

Why Augmentin Is Not Appropriate for Uncomplicated Strep Throat

• Amoxicillin alone remains the drug of choice for Group A streptococcal pharyngitis because of its proven efficacy, narrow spectrum, excellent safety profile, low cost, and the complete absence of documented penicillin resistance in Group A Streptococcus worldwide. 1, 2

• Augmentin (amoxicillin-clavulanate) is reserved for treatment failures or chronic carriers who have not responded to initial amoxicillin therapy, not for first-line treatment of uncomplicated strep throat. 1, 2

• The clavulanate component in Augmentin is unnecessary for strep pharyngitis because Group A Streptococcus does not produce β-lactamase enzymes; adding clavulanate only increases cost, gastrointestinal side effects (especially diarrhea), and unnecessarily broadens the antimicrobial spectrum. 1, 3

Correct First-Line Amoxicillin Dosing for This Child

Weight-Based Calculation

• This 16.8 kg child should receive amoxicillin 50 mg/kg once daily = 840 mg once daily (maximum 1,000 mg) for 10 days. 1, 2

• Alternative twice-daily regimen: 25 mg/kg per dose = 420 mg twice daily (maximum 500 mg per dose) for 10 days. 1, 2

• Both once-daily and twice-daily amoxicillin regimens have identical efficacy (strong, high-quality evidence), but once-daily dosing may improve adherence. 2, 4, 5

Mandatory Treatment Duration

• A full 10-day course is essential to achieve maximal pharyngeal eradication and prevent acute rheumatic fever, even if symptoms resolve within 3–4 days. 1, 2

• Shortening the course by even a few days dramatically increases treatment failure rates and rheumatic fever risk. 1, 2

When Augmentin Would Be Appropriate

Treatment Failure or Chronic Carrier

• If this child fails initial amoxicillin therapy or is a chronic carrier, then prescribe amoxicillin-clavulanate at 40 mg/kg/day of the amoxicillin component divided into 3 doses (maximum 2,000 mg/day) for 10 days. 1, 2

• For a 16.8 kg child, this equals approximately 224 mg of amoxicillin per dose three times daily. 1, 2

Calculation Using Available Augmentin Formulations

• Using the 200 mg/5 mL suspension (200 mg amoxicillin per 5 mL): Give approximately 5.6 mL three times daily. 6

• Using the 400 mg/5 mL suspension (400 mg amoxicillin per 5 mL): Give approximately 2.8 mL three times daily. 6

Critical Pitfalls to Avoid

• Do not prescribe Augmentin for uncomplicated, first-episode strep throat—this is inappropriate antibiotic stewardship and exposes the child to unnecessary side effects and cost. 1, 2

• Do not use the twice-daily Augmentin formulation (45 mg/kg/day) for strep pharyngitis—the three-times-daily regimen (40 mg/kg/day) is specifically recommended for treatment failures and chronic carriers. 1, 2

• Do not shorten the antibiotic course below 10 days (except azithromycin's 5-day regimen if the child has a penicillin allergy), as this markedly increases treatment failure and rheumatic fever risk. 1, 2

• Do not order routine post-treatment throat cultures for asymptomatic patients who have completed therapy; reserve testing for special circumstances such as a history of rheumatic fever. 1

Alternatives for Penicillin-Allergic Patients

Non-Anaphylactic Penicillin Allergy

• Cephalexin 20 mg/kg per dose twice daily (336 mg per dose for this child, maximum 500 mg per dose) for 10 days is the preferred alternative with only 0.1% cross-reactivity risk. 1, 2

Immediate/Anaphylactic Penicillin Allergy

• Clindamycin 7 mg/kg per dose three times daily (118 mg per dose for this child, maximum 300 mg per dose) for 10 days is the preferred choice, with only ~1% resistance among U.S. Group A Streptococcus isolates. 1, 2

• Azithromycin 12 mg/kg once daily (202 mg for this child, maximum 500 mg) for 5 days is an acceptable alternative, but macrolide resistance ranges from 5–8% in the United States. 1, 2

Adjunctive Symptomatic Treatment

• Offer acetaminophen or ibuprofen for moderate to severe sore throat or fever; these provide effective pain and inflammation reduction. 1

• Avoid aspirin in children due to Reye syndrome risk. 1

• Corticosteroids are not recommended as adjunctive therapy. 1