Oral Liquid Cephalexin Dosing for a 6-Year-Old with Acute Otitis Media
Cephalexin is not the optimal antibiotic choice for acute otitis media in a 6-year-old child; however, if it must be used, the dose is 50-100 mg/kg/day divided into 3-4 doses for 10 days. 1, 2
Why Cephalexin Is Suboptimal for Otitis Media
- Cephalexin has a critical gap in coverage against Haemophilus influenzae, which causes approximately 30% of acute otitis media cases, with a 50% failure rate when this organism is present. 1
- Historical data from 97 children treated with cephalexin monohydrate suspension showed that 5 of 7 treatment failures were due to persistent H. influenzae infection. 2
- Modern guidelines do not recommend cephalexin as first-line or alternative therapy for acute otitis media because of this microbiological weakness. 3, 4
Recommended Alternative Antibiotics
If the child has not received antibiotics in the past 4-6 weeks and has no penicillin allergy, prescribe high-dose amoxicillin 80-90 mg/kg/day divided twice daily for 10 days. 4
- For a typical 6-year-old weighing 20 kg, this equals 1600-1800 mg/day (800-900 mg twice daily). 4
- High-dose amoxicillin achieves adequate middle ear concentrations against drug-resistant Streptococcus pneumoniae, the most common pathogen. 4
If the child has recent antibiotic exposure (within 4-6 weeks) or non-anaphylactic penicillin allergy, prescribe cefdinir 14 mg/kg/day given once daily or divided into two doses for 5-10 days. 3
- For a 20 kg child, this equals 280 mg/day (280 mg once daily or 140 mg twice daily). 3
- Cefdinir offers superior palatability compared to other cephalosporins, improving adherence. 3
If Cephalexin Must Be Used
The dosing range is 50-100 mg/kg/day divided into 3-4 doses, with 100 mg/kg/day preferred for otitis media to maximize efficacy against susceptible organisms. 1, 2
- For a 20 kg child: 2000 mg/day total, given as 500 mg four times daily or 667 mg three times daily. 1, 2
- Treatment duration should be 10 days. 1, 2
- The oral suspension is typically available as 125 mg/5 mL or 250 mg/5 mL. 5
Critical Monitoring Points
- Reassess at 48-72 hours: if fever persists, ear pain worsens, or the child deteriorates, switch to high-dose amoxicillin-clavulanate (90 mg/kg/day of amoxicillin component) or intramuscular ceftriaxone 50 mg/kg/day. 4
- Address pain management with acetaminophen or ibuprofen regardless of antibiotic choice. 4
- Persistent middle ear effusion at 2-4 weeks post-treatment is common (40-70%) and does not require additional antibiotics unless acute symptoms recur. 4
Common Pitfalls to Avoid
- Do not use cephalexin if H. influenzae is suspected or documented, as treatment failure is highly likely. 1
- Do not underdose: the 50 mg/kg/day lower range has inferior outcomes in otitis media compared to 100 mg/kg/day. 1, 2
- Do not prescribe cephalexin as first-line therapy when guideline-recommended alternatives (amoxicillin, cefdinir) are available and appropriate. 3, 4