Maximum Amoxicillin Dose for Pediatric Otitis Media
For a 5-year-old child weighing 25 kg with otitis media, the maximum recommended dose is 90 mg/kg/day of amoxicillin, which equals 2,250 mg per day (1,125 mg twice daily), divided into two doses. 1
Weight-Based Calculation
- This patient requires 90 mg/kg/day × 25 kg = 2,250 mg total daily dose 1
- Administered as 1,125 mg twice daily (every 12 hours) 1
- The absolute maximum daily dose regardless of weight is 4,000 mg/day 2, 3
Rationale for High-Dose Regimen
High-dose amoxicillin (80-90 mg/kg/day) is the standard of care for acute otitis media in children, not an optional alternative. 1 This dosing is necessary because:
- It provides adequate middle ear fluid concentrations to overcome penicillin-resistant Streptococcus pneumoniae with MICs up to 2-4 mg/L 4, 5
- Standard dosing of 40 mg/kg/day is inadequate and outdated, particularly given current resistance patterns 4, 6
- The AAP/AAFP guidelines explicitly recommend 80-90 mg/kg/day as the appropriate dose when amoxicillin is used 1
When to Use Amoxicillin-Clavulanate Instead
Switch to amoxicillin-clavulanate (90 mg/kg/day of amoxicillin component with 6.4 mg/kg/day clavulanate) if the child has: 2, 6
- Recent antibiotic use within the past 30 days 2
- Concurrent purulent conjunctivitis (suggests H. influenzae) 2
- Treatment failure after 48-72 hours on amoxicillin alone 1
- Severe illness at presentation 1, 2
Treatment Duration and Monitoring
- Continue treatment for 10 days for children under 6 years with acute otitis media 1
- Reassess at 48-72 hours if symptoms persist or worsen 1
- Clinical improvement should be evident within the first 24-48 hours, though complete resolution may take longer 1
Critical Dosing Considerations
The 90 mg/kg/day regimen should be divided into two doses (every 12 hours), not three doses, as this maintains adequate middle ear fluid concentrations throughout the dosing interval. 1, 2 Taking amoxicillin at the start of meals minimizes gastrointestinal side effects. 7
Common Pitfall to Avoid
Do not use the outdated 40-45 mg/kg/day dosing for otitis media. 4 This lower dose was standard decades ago but is now recognized as inadequate for eradicating resistant S. pneumoniae, the most common bacterial pathogen in AOM. 4, 6 Using subtherapeutic doses promotes treatment failure and antimicrobial resistance. 2