Amoxicillin Dosing for Acute Otitis Media
For this 6-year-old child weighing 20.8 kg with acute otitis media, prescribe amoxicillin 80-90 mg/kg/day divided into two doses, which equals 1,664-1,872 mg/day total, or approximately 830-935 mg twice daily using the 400 mg/5 mL suspension (10.4-11.7 mL twice daily). 1
Dosing Calculation
The 2013 AAP guidelines establish high-dose amoxicillin (80-90 mg/kg/day in 2 divided doses) as first-line treatment for acute otitis media 1. For this patient:
- Weight: 20.8 kg
- Total daily dose: 1,664-1,872 mg/day (80-90 mg/kg/day)
- Per dose (twice daily): 832-936 mg per dose
- Using 400 mg/5 mL suspension: 10.4-11.7 mL twice daily
Practical prescription: Round to 10-12 mL (800-960 mg) twice daily for 10 days.
Rationale for High-Dose Therapy
High-dose amoxicillin is recommended as first-line therapy because it:
- Provides effective coverage against Streptococcus pneumoniae, including intermediate penicillin-resistant strains 1
- Maintains safety and tolerability 1
- Has narrow microbiologic spectrum, acceptable taste, and low cost 1
The 2017 otolaryngology guidelines confirm that oral antibiotics reduce pain at 2-3 days (NNT=20) 2, supporting antibiotic use in appropriately diagnosed AOM.
Important Clinical Considerations
When to Use Amoxicillin-Clavulanate Instead
Switch to high-dose amoxicillin-clavulanate (90 mg/kg/day of amoxicillin component) if the child has 1:
- Taken amoxicillin in the previous 30 days
- Concurrent purulent conjunctivitis (otitis-conjunctivitis syndrome)
- Need for β-lactamase coverage
Dosing Pitfall in This Age Group
Critical caveat: Research shows that children in this weight range (around 20 kg) often receive inappropriately low doses because clinicians become reluctant to exceed "adult maximum doses" 3, 4. At 20.8 kg, this child's calculated dose (1,664-1,872 mg/day) approaches but does not exceed the typical adult maximum of 1,500-2,000 mg/day. Do not artificially cap the dose at adult maximums for weight-based pediatric dosing 3.
Administration Instructions
- Administer every 12 hours (twice daily dosing) 1
- May be given with or without food 5
- Use a calibrated oral syringe for accurate measurement 5
- Shake suspension well before each use 5
- Refrigeration is preferable but not required 5
- Discard unused suspension after 14 days 5
Treatment Duration
Standard treatment duration is 10 days for children under 6 years of age, though the guidelines support this approach for children in this age range with AOM 1.
Follow-up Considerations
Reassess at 48-72 hours if symptoms worsen or fail to improve. If treatment fails, switch to amoxicillin-clavulanate (90 mg/kg/day of amoxicillin component) or ceftriaxone 1.