At what age and weight should children discontinue amoxicillin 90 mg/kg dosing for acute otitis media?

High-Dose Amoxicillin (90 mg/kg/day) Should Be Capped at the Standard Adult Dose of 1,500 mg/day, Which Typically Occurs Around Age 6 Years or Weight 17-20 kg

Weight-Based Dosing Threshold

When a child's weight-based calculation (90 mg/kg/day) exceeds the standard adult dose of 1,500 mg/day, prescribe the adult dose instead. This threshold is typically reached at approximately 17-20 kg body weight. 1

• The American Academy of Pediatrics recommends 80-90 mg/kg/day divided twice daily for acute otitis media, but this recommendation was developed without explicit discussion of obesity or maximum dose specifications. 2, 1
• In practice, primary care physicians prescribe significantly lower doses in older children and those in higher weight categories, with most capping at the standard adult dose. 1
• Among AAP guideline subcommittee members surveyed, 67% would prescribe the standard adult dose (1,500 mg/day) when weight-based calculations exceed this amount, while only 33% would continue with 80-90 mg/kg/day dosing. 1

Age-Based Considerations

Children under 2 years of age should receive the full 80-90 mg/kg/day dosing regardless of weight because this age group has the highest risk of treatment failure due to eustachian tube dysfunction and immune immaturity. 3, 4, 5

• The 10-day treatment duration is specifically recommended for children younger than 6 years. 3
• Children 6 years and older typically weigh enough that weight-based dosing would exceed adult doses, making the adult dose cap clinically appropriate. 3

Practical Dosing Algorithm

Follow this stepwise approach:

1. For children < 2 years: Calculate 80-90 mg/kg/day divided BID, regardless of total daily dose. 3, 5
2. For children 2-6 years: Calculate 80-90 mg/kg/day divided BID; if this exceeds 1,500 mg/day, cap at 1,500 mg/day (750 mg BID). 1
3. For children ≥ 6 years: Use standard adult dosing of 1,500 mg/day (750 mg BID). 3

Critical Caveats

The evidence base for maximum dose specifications is limited. The original AAP/AAFP guidelines did not address obesity or maximum dosing, and current practice patterns reflect clinical judgment rather than evidence-based thresholds. 1

• Children weighing ≤20 kg receive significantly higher mean daily doses (74.2 mg/kg/day) compared to heavier children (40.4 mg/kg/day), demonstrating real-world dose capping. 1
• High-dose amoxicillin achieves 87% coverage of Streptococcus pneumoniae isolates (including intermediately resistant strains), compared to 83% with standard dosing, but this pharmacodynamic advantage must be balanced against practical dosing limits. 3

When to Switch to Amoxicillin-Clavulanate

Regardless of age or weight, switch to high-dose amoxicillin-clavulanate (90 mg/kg/day amoxicillin + 6.4 mg/kg/day clavulanate, 14:1 ratio) when:

• The child received amoxicillin within the prior 30 days. 3
• Concurrent purulent conjunctivitis is present. 3
• The child attends daycare (β-lactamase-producing organisms more likely). 3
• No clinical improvement occurs within 48-72 hours on amoxicillin alone. 2, 3

The 14:1 ratio formulation causes significantly less diarrhea than older 7:1 formulations while maintaining efficacy against β-lactamase-producing organisms. 6, 3