Amoxicillin Dosing for Infant Ear Infection
For an infant with acute otitis media (AOM), the recommended first-line treatment is high-dose amoxicillin at 80-90 mg/kg/day divided into 2 doses daily for 10 days. 1
Standard First-Line Dosing
High-dose amoxicillin (80-90 mg/kg/day) given in 2 divided doses is the preferred initial therapy for most infants with AOM due to its effectiveness against common bacterial pathogens including Streptococcus pneumoniae and Haemophilus influenzae, excellent safety profile, low cost, and narrow antimicrobial spectrum. 1
The high-dose regimen achieves middle ear fluid concentrations that exceed the minimum inhibitory concentration (MIC) for intermediately resistant S. pneumoniae and many highly resistant strains, providing superior bacteriologic and clinical efficacy compared to standard dosing. 1
Treatment duration should be 10 days to ensure adequate bacterial eradication and prevent complications. 2
Special Circumstances Requiring Modified Approach
If the infant has taken amoxicillin within the previous 30 days, has concurrent conjunctivitis, or requires coverage for β-lactamase-producing organisms, initiate therapy with high-dose amoxicillin-clavulanate (90 mg/kg/day of amoxicillin component with 6.4 mg/kg/day of clavulanate in a 14:1 ratio, given in 2 divided doses). 1
Age-Specific Considerations for Infants Under 3 Months
For infants younger than 12 weeks (3 months), the maximum recommended dose is 30 mg/kg/day divided every 12 hours due to incompletely developed renal function affecting amoxicillin elimination. 2
Treatment should continue for at least 48-72 hours beyond symptom resolution or evidence of bacterial eradication. 2
Treatment Failure Protocol
If no clinical improvement occurs within 48-72 hours:
Switch to high-dose amoxicillin-clavulanate (90 mg/kg/day of amoxicillin with 6.4 mg/kg/day of clavulanate in 2 divided doses). 1
Alternatively, consider ceftriaxone 50 mg/kg IM or IV daily for 3 days. 1
The predominant pathogens in treatment failures are β-lactamase-producing H. influenzae (found in 64% of bacteriologic failures), making β-lactamase-stable antibiotics the appropriate second-line choice. 3
Important Clinical Pitfalls to Avoid
Do not use standard-dose amoxicillin (40-45 mg/kg/day) as it provides inadequate middle ear fluid concentrations to eradicate resistant S. pneumoniae, particularly during viral coinfection which further reduces antibiotic penetration. 4
Research demonstrates that approximately 87% of S. pneumoniae isolates are susceptible to high-dose amoxicillin versus only 83% to standard dosing. 1
Viral coinfection, present in up to 40% of AOM cases, significantly reduces amoxicillin middle ear fluid penetration (geometric mean concentration 2.7 μg/mL with viral infection versus 5.7 μg/mL with bacterial-only infection), further supporting the need for high-dose therapy. 4
Administration Guidance
Administer amoxicillin at the start of a meal to minimize gastrointestinal intolerance. 2
For oral suspension, shake well before each use and refrigerate after reconstitution (though not required); discard unused portion after 14 days. 2
The suspension can be mixed with formula, milk, or fruit juice if needed, but must be consumed immediately after mixing. 2