What is the appropriate amoxicillin dose for a 5-year-old female with acute otitis media weighing 15 kg?

Amoxicillin Dosing for 5-Year-Old with Acute Otitis Media

For a 5-year-old female weighing 15 kg with acute otitis media, prescribe high-dose amoxicillin at 80–90 mg/kg/day divided into two doses, which equals 600–675 mg twice daily (1,200–1,350 mg total daily dose) for 7–10 days depending on symptom severity. 1

Exact Dose Calculation

• Calculate the total daily dose: 15 kg × 80 mg/kg = 1,200 mg/day (minimum) or 15 kg × 90 mg/kg = 1,350 mg/day (maximum) 1
• Divide into two equal doses given 12 hours apart: 600 mg twice daily or 675 mg twice daily 1
• Maximum single dose is 2,000 mg (not applicable to this patient) 2

Treatment Duration Based on Severity

• For mild-to-moderate symptoms: 7-day course is equally effective as 10 days in children 2–5 years old 3
• For severe symptoms (moderate-to-severe otalgia, otalgia ≥48 hours, or fever ≥39°C): prescribe a full 10-day course 3

When to Switch to Amoxicillin-Clavulanate Instead

Use amoxicillin-clavulanate (90 mg/kg/day amoxicillin + 6.4 mg/kg/day clavulanate, divided twice daily) as first-line therapy if any of the following apply: 1, 2

• The child received amoxicillin within the previous 30 days 1
• Concurrent purulent conjunctivitis is present (suggests Haemophilus influenzae) 1, 2
• The child attends daycare (higher risk of β-lactamase-producing organisms) 2

For this 15 kg patient, amoxicillin-clavulanate would be: 1,350 mg amoxicillin + 96 mg clavulanate total daily, divided into 675 mg/48 mg twice daily 2

Pain Management (Critical First Step)

• Initiate acetaminophen or ibuprofen immediately for all children with ear pain, regardless of antibiotic decision 3
• Analgesics provide relief within 24 hours, whereas antibiotics provide no symptomatic benefit in the first 24 hours 3
• Continue pain medication throughout the acute phase 3

Reassessment Protocol

• Re-evaluate at 48–72 hours if symptoms worsen or fail to improve 1, 3
• If amoxicillin fails, switch to amoxicillin-clavulanate 1
• If amoxicillin-clavulanate fails, administer intramuscular ceftriaxone 50 mg/kg once daily for 3 consecutive days 1, 3

Rationale for High-Dose Therapy

• High-dose amoxicillin achieves middle ear fluid concentrations that exceed the minimum inhibitory concentration for approximately 87% of Streptococcus pneumoniae isolates, including intermediately resistant strains 1
• This is superior to standard-dose amoxicillin, which covers only 83% of pneumococcal isolates 1
• The three principal pathogens—S. pneumoniae, H. influenzae, and Moraxella catarrhalis—are adequately covered by this regimen 1

Common Pitfalls to Avoid

• Do not use standard-dose amoxicillin (40–45 mg/kg/day) in areas with drug-resistant S. pneumoniae 1
• Do not prescribe azithromycin or other macrolides as first-line therapy—pneumococcal macrolide resistance exceeds 40% in the United States, with bacterial failure rates of 20–25% 3
• Do not use trimethoprim-sulfamethoxazole or erythromycin-sulfisoxazole for treatment failures due to substantial resistance 3
• The 14:1 ratio formulation of amoxicillin-clavulanate causes significantly less diarrhea than older 7:1 formulations 1, 2

Post-Treatment Expectations

• Middle ear effusion persists in 60–70% of children at 2 weeks after successful treatment, declining to 40% at 1 month and 10–25% at 3 months 3
• This post-treatment effusion (otitis media with effusion) requires monitoring but not additional antibiotics unless it persists >3 months with hearing loss 3