Augmentin Dosing for Children Over 40 kg
For children weighing more than 40 kg, prescribe adult dosing of Augmentin rather than weight-based pediatric dosing. 1
Key Dosing Principle
The FDA-approved Augmentin ES-600 formulation explicitly states that experience with this high-dose pediatric suspension in children weighing 40 kg or more is not available 1. This represents a critical transition point where pediatric weight-based dosing ends and adult fixed dosing begins.
Recommended Adult Dosing for Children ≥40 kg
For children who have reached 40 kg or more, use standard adult Augmentin formulations:
- Standard infections: 500 mg/125 mg tablet three times daily OR 875 mg/125 mg tablet twice daily
- Severe infections or resistant pathogens: Doses may be doubled, with maximum daily amoxicillin dose of 4 grams 2, 3
The British Thoracic Society guidelines confirm this approach, recommending one 250/125 mg tablet for children 12-18 years for standard dosing 4, though children over 40 kg often reach this weight before age 12.
Clinical Context from Guidelines
The IDSA/PIDS pediatric pneumonia guidelines specify that for children ≥5 years with community-acquired infections, oral amoxicillin dosing reaches a maximum of 4 g/day 2, 3. This ceiling effectively transitions larger children to adult dosing patterns, as weight-based calculations (90 mg/kg/day) would exceed this maximum in children over approximately 44 kg.
Important Caveats
The dosing disparity problem: Recent evidence demonstrates that larger children systematically receive lower mg/kg doses than smaller children 5. Children above 60 kg frequently receive less than 40 mg/kg/day when guidelines recommend 80-90 mg/kg/day for resistant pathogens. This occurs because clinicians hesitate to exceed "adult maximum doses" even when weight-based calculations would justify higher dosing.
For infections requiring high-dose therapy (e.g., resistant Streptococcus pneumoniae, acute otitis media with risk factors): Consider that a 40 kg child receiving the adult dose of 875 mg twice daily (1750 mg/day total amoxicillin) only achieves 43.75 mg/kg/day—well below the recommended 80-90 mg/kg/day 2. In these cases, prescribe two 875/125 mg tablets twice daily (3500 mg amoxicillin/day) to approach appropriate weight-based dosing, staying within the 4 g/day maximum.
Formulation considerations: The 2000 mg extended-release tablet (Augmentin XR) twice daily is FDA-approved for adults with resistant respiratory pathogens 6 and may be appropriate for adolescents who have reached skeletal maturity, though pediatric data are limited.
Practical Algorithm
- Child weighs 40-50 kg with standard infection: 875/125 mg twice daily
- Child weighs 40-50 kg with resistant pathogen risk: Two 875/125 mg tablets twice daily (3500 mg/day amoxicillin)
- Child weighs >50 kg: Standard adult dosing (875/125 mg twice daily for most infections)
- Severe infection regardless of weight >40 kg: Consider doubling standard adult dose up to 4 g/day maximum
The clavulanate component remains adequate at adult fixed doses (125-250 mg per dose) to inhibit β-lactamase-producing organisms across all weight ranges 4, 7.