At what age can augmentin (amoxicillin‑clavulanate) be started at 90 mg/kg/day?

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Last updated: February 8, 2026View editorial policy

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Augmentin 90 mg/kg/day Can Be Started at 3 Months of Age

Augmentin (amoxicillin-clavulanate) at the high-dose regimen of 90 mg/kg/day may be initiated in children ≥3 months of age when bacterial infection is suspected or confirmed. 1

Age-Based Safety and Approval

  • The minimum age for initiating Augmentin is 3 months, as safety and efficacy data are robust for children at or above this age but remain limited for younger infants. 1

  • Pharmacokinetic studies demonstrate reliable metabolism and clearance of the clavulanate component only after the neonatal period (≥3 months), which supports this age cutoff. 1

  • For infants younger than 3 months with suspected serious bacterial infection, intravenous regimens (e.g., ampicillin plus gentamicin or cefotaxime) are preferred over oral Augmentin. 1

High-Dose Regimen Specifications

  • The high-dose formulation is defined as 90 mg/kg/day of amoxicillin with 6.4 mg/kg/day of clavulanate, administered in two divided doses. 1

  • This regimen provides a 14:1 ratio of amoxicillin to clavulanate in oral suspension, which causes less diarrhea than other amoxicillin-clavulanate preparations while maintaining efficacy. 1

Primary Indications in Children ≥3 Months

  • The high-dose regimen is indicated for acute otitis media, community-acquired pneumonia, and acute bacterial rhinosinusitis in children 3 months and older. 1

  • For presumed bacterial pneumonia in outpatient children under 5 years old, the American Academy of Pediatrics recommends the amoxicillin component at 90 mg/kg/day in 2 doses. 1

Risk Factors Requiring High-Dose Therapy

High-dose amoxicillin-clavulanate (90 mg/kg/day) is specifically indicated when any of the following risk factors are present: 1

  • Age <2 years
  • Daycare attendance
  • Recent antibiotic use within the previous 30 days
  • Incomplete Haemophilus influenzae type b vaccination (fewer than 3 injections)
  • Geographic area with high prevalence of penicillin-resistant S. pneumoniae (>10%)
  • Moderate to severe illness at presentation

Clinical Efficacy Against Resistant Pathogens

  • The high-dose formulation achieves middle ear fluid concentrations adequate to overcome penicillin-resistant S. pneumoniae based on acute otitis media data. 1

  • High-dose amoxicillin (80-90 mg/kg/day) exceeds the minimum inhibitory concentration for intermediately resistant S. pneumoniae and many highly resistant serotypes. 1

  • The high-dose formulation (90/6.4 mg/kg/day) eradicated penicillin-resistant S. pneumoniae with MICs of 2-4 mg/L in clinical trials, with clinical response rates of 76-95%. 1

Treatment Duration and Monitoring

  • The Infectious Diseases Society of America recommends treatment courses of 10 days for most pediatric infections, including acute otitis media and community-acquired pneumonia. 1

  • Clinical improvement should be evident within 48-72 hours after initiating therapy; if no improvement or worsening occurs, reevaluation and consideration of switching antibiotics or further investigation is recommended. 1

Common Pitfalls to Avoid

  • Using standard doses when high-dose therapy is indicated leads to treatment failure with resistant organisms. 1

  • Verify the suspension concentration (125/31 vs 250/62) before calculating volume to avoid dosing errors. 1

  • If oral Augmentin is deemed absolutely necessary in a critically ill 1-2 month-old infant, specialist consultation should be obtained before prescribing. 1

  • French pediatric guidelines explicitly limit acute otitis media recommendations to children over 3 months, reinforcing the age restriction. 1

References

Guideline

Amoxicillin-Clavulanate Dosing in Pediatric Patients

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2026

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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