What is the dosage and treatment duration of cephalexin (cephalosporin) for an ear infection?

Cephalexin Dosage for Ear Infections

For ear infections, cephalexin is not recommended as first-line therapy due to its ineffectiveness against common pathogens, particularly Haemophilus influenzae. 1 Instead, amoxicillin or amoxicillin-clavulanate should be used as first-line treatment for acute otitis media.

First-Line Treatment Options for Ear Infections

• Amoxicillin: 80-90 mg/kg/day in 2 divided doses 1, 2
• Amoxicillin-clavulanate: 90 mg/kg/day of amoxicillin with 6.4 mg/kg/day of clavulanate in 2 divided doses (for patients who have taken amoxicillin in the previous 30 days or have concurrent conjunctivitis) 1, 2

When Cephalexin Might Be Used (Despite Not Being First-Line)

If cephalexin must be used (e.g., in specific cases of penicillin allergy where other alternatives aren't suitable), the FDA-approved dosing is:

• Adults: 250 mg every 6 hours (1-4g daily in divided doses) 3
• Children: 75-100 mg/kg/day in 4 divided doses specifically for otitis media 3, 4
• Duration: 10-12 days 4

Why Cephalexin Is Not Recommended for Ear Infections

First-generation cephalosporins like cephalexin have poor coverage for Haemophilus influenzae, a common pathogen in ear infections 1. The Journal of Allergy and Clinical Immunology explicitly states that first-generation cephalosporins such as cephalexin are "ineffective for treatment" and "should not be used" for sinusitis and related infections 1.

Better Cephalosporin Options for Ear Infections

If a cephalosporin is needed (e.g., in case of non-severe penicillin allergy), the following are preferred:

• Cefdinir: 14 mg/kg/day in 1-2 doses 1, 2
• Cefuroxime: 30 mg/kg/day in 2 divided doses 1
• Cefpodoxime: 10 mg/kg/day in 2 divided doses 1

Treatment Algorithm for Ear Infections

1. First episode of acute otitis media:

   • Use amoxicillin 80-90 mg/kg/day in 2 divided doses for 10 days 1, 2

2. Recent amoxicillin use (within 30 days) or concurrent conjunctivitis:

   • Use amoxicillin-clavulanate 90 mg/kg/day in 2 divided doses for 10 days 1, 2

3. Penicillin allergy:

   • For non-severe allergy: Cefdinir, cefuroxime, or cefpodoxime 1, 2
   • For severe allergy: Clindamycin or macrolides (though macrolides have limited effectiveness) 2

4. Treatment failure after 48-72 hours:

   • Switch to amoxicillin-clavulanate if initially on amoxicillin 1
   • Consider ceftriaxone (50 mg IM or IV for 3 days) if failing on amoxicillin-clavulanate 1
   • Consider clindamycin (30-40 mg/kg/day in 3 divided doses) with or without a third-generation cephalosporin 1, 2

Important Clinical Considerations

• Clinical improvement should be noted within 48-72 hours; if no improvement occurs, reassess diagnosis or consider alternative antibiotics 2
• Persistent middle ear effusion is common after successful treatment (60-70% at 2 weeks, 40% at 1 month) and does not necessarily indicate treatment failure if symptoms have resolved 2
• Pain management with acetaminophen or ibuprofen is essential regardless of antibiotic choice 2

Conclusion

While cephalexin has FDA-approved dosing for otitis media at 75-100 mg/kg/day in 4 divided doses for 10-12 days, it is not recommended due to inadequate coverage against common ear infection pathogens. Amoxicillin or amoxicillin-clavulanate should be used as first-line therapy, with specific second or third-generation cephalosporins as alternatives in cases of penicillin allergy.