What is the recommended dose of amoxicillin (amoxicillin) for a 13-year-old with otitis media?

Amoxicillin Dosing for Acute Otitis Media in a 13-Year-Old

For a 13-year-old with acute otitis media, the recommended dose of amoxicillin is 80-90 mg/kg/day divided twice daily, with a maximum of 2-3 grams per day. 1

First-Line Treatment Algorithm

Initial Assessment

• Confirm diagnosis of acute otitis media (AOM) based on:
  • Distinct erythema of the tympanic membrane
  • Middle ear effusion
  • Signs of inflammation
  • Presence of otalgia (ear pain)

Antibiotic Selection and Dosing

1. First-line therapy: Amoxicillin

   • Dosage: 80-90 mg/kg/day divided twice daily 1
   • For a 13-year-old (likely weighing >40 kg), use adult dosing:
     • 875 mg twice daily or 500 mg three times daily
   • Duration: 5-7 days for uncomplicated AOM

2. For penicillin allergy (non-Type I hypersensitivity):

   • Cefdinir, cefpodoxime, or cefuroxime 1

Rationale for High-Dose Amoxicillin

• High-dose amoxicillin (80-90 mg/kg/day) is recommended over standard dose (40-45 mg/kg/day) to overcome intermediate and highly resistant pneumococcal strains 1
• Higher doses achieve middle ear fluid levels that exceed the minimum inhibitory concentration for longer periods, improving both bacteriologic and clinical efficacy 1
• The American Academy of Pediatrics and American Academy of Family Physicians specifically recommend this higher dosage based on microbiologic studies and expert opinion 1

Treatment Failure Management

If no improvement within 48-72 hours:

1. Reassess to confirm AOM diagnosis and exclude other causes
2. Switch to amoxicillin-clavulanate (90 mg/kg/day of amoxicillin component) if initial treatment was amoxicillin alone 1
3. Consider tympanocentesis or referral if second-line therapy fails

Important Clinical Considerations

• Twice-daily dosing is preferred over three-times-daily dosing as it:

  • Shows comparable efficacy 2
  • Is associated with significantly less diarrhea (14% vs. 34%) 3
  • Improves medication compliance 4

• Pain management should be addressed regardless of antibiotic use, especially during the first 24 hours 1

• For patients weighing ≥40 kg (most 13-year-olds), adult dosing can be used, but should not exceed 3 grams per day 3

Common Pitfalls to Avoid

• Underdosing: Using standard-dose amoxicillin (40-45 mg/kg/day) may be inadequate for resistant strains of S. pneumoniae, particularly during viral co-infection 5
• Inappropriate duration: Shorter courses may be insufficient; 5-7 days is generally appropriate for uncomplicated cases 1
• Neglecting pain management: Pain control should be addressed regardless of antibiotic therapy 1
• Unnecessary broad-spectrum coverage: Amoxicillin remains first-line therapy before escalating to broader agents like amoxicillin-clavulanate 1

By following this evidence-based approach with high-dose amoxicillin as first-line therapy, you can optimize treatment outcomes while minimizing adverse effects and antibiotic resistance development in adolescents with acute otitis media.