Amoxicillin Dosing for Acute Otitis Media in a 4-Year-Old
Prescribe high-dose amoxicillin at 80–90 mg/kg/day divided into two doses for 10 days, which equals 1,280–1,440 mg total daily (640–720 mg twice daily) for this 15.97 kg child. 1
Dose Calculation
For a child weighing 15.97 kg, multiply the weight by 80–90 mg/kg to get the total daily dose of 1,278–1,437 mg, then divide by 2 to give approximately 640–720 mg twice daily (every 12 hours). 1
Practical prescribing would be 650–700 mg twice daily, depending on available suspension concentrations. 2
The maximum single dose is 2,000 mg, which is well above this child's calculated dose. 3
Rationale for High-Dose Therapy
High-dose amoxicillin achieves middle ear fluid concentrations exceeding the minimum inhibitory concentration for approximately 87% of Streptococcus pneumoniae isolates, including intermediately resistant strains, compared to only 83% with standard dosing. 1
This regimen provides adequate coverage against the three principal pathogens: Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis. 1
Research confirms that high-dose amoxicillin achieves 92% eradication of S. pneumoniae from middle ear fluid by days 4–6. 4
Treatment Duration
Treat for 10 days in children younger than 6 years of age. 1, 2
While some guidelines suggest 5 days may be sufficient for children over 2 years with uncomplicated cases, the American Academy of Pediatrics recommends 10 days for children under 6 years. 1, 2
When to Switch to Amoxicillin-Clavulanate
Switch to high-dose amoxicillin-clavulanate (90 mg/kg/day amoxicillin + 6.4 mg/kg/day clavulanate in a 14:1 ratio, divided twice daily) if: 1, 3
- The child received amoxicillin within the previous 30 days
- Concurrent purulent conjunctivitis is present
- The child attends daycare (increased risk of β-lactamase-producing organisms)
Monitoring and Treatment Failure
Clinical improvement should be evident within 48–72 hours; if no improvement occurs, reassess the diagnosis and consider treatment failure. 1, 2
If the child fails to improve on amoxicillin after 48–72 hours, switch to high-dose amoxicillin-clavulanate. 1, 3
If amoxicillin-clavulanate fails, consider ceftriaxone 50 mg/kg intramuscularly or intravenously for three days. 1, 3
Important Clinical Caveats
Address pain management concurrently during the first 24 hours regardless of antibiotic choice. 2
Twice-daily dosing is as effective as three-times-daily administration and improves adherence. 2, 5
The predominant cause of treatment failure with amoxicillin is β-lactamase-producing H. influenzae, which occurs in approximately 34% of cases. 4
If using amoxicillin-clavulanate, the 14:1 ratio formulation causes significantly less diarrhea than older 7:1 formulations. 1, 3