What is the appropriate amoxicillin dose and duration for a 22‑month‑old child weighing 24.13 lb with uncomplicated acute otitis media?

Amoxicillin Dosing for Acute Otitis Media in a 22-Month-Old

For this 22-month-old child weighing 24.13 lbs (10.96 kg), prescribe high-dose amoxicillin 90 mg/kg/day divided into two doses every 12 hours for a full 10-day course, which equals approximately 985 mg total daily (492.5 mg per dose, rounded to 500 mg twice daily). 1

Weight-Based Calculation

• The child weighs 24.13 lbs = 10.96 kg (24.13 ÷ 2.2)
• High-dose amoxicillin dosing: 80–90 mg/kg/day divided twice daily 1
• Using 90 mg/kg/day: 90 × 10.96 kg = 987 mg total daily dose
• Divided twice daily: 493.5 mg per dose (round to 500 mg twice daily for practical administration) 1
• Using common suspension concentrations (400 mg/5 mL): administer 6.2 mL twice daily 2

Rationale for High-Dose Therapy

• All children younger than 2 years with acute otitis media require a 10-day antibiotic course regardless of severity 1
• High-dose amoxicillin (80–90 mg/kg/day) achieves middle ear fluid concentrations that overcome penicillin-resistant Streptococcus pneumoniae (MIC 0.12–2.0 µg/mL), which accounts for approximately 48% of pneumococcal isolates in symptomatic children 1, 3, 4
• This dosing provides 92% eradication of S. pneumoniae including penicillin-nonsusceptible strains 4
• The maximum single dose is capped at 2 grams per dose regardless of weight 1, 2

Treatment Duration

• 10 days is mandatory for all children under 2 years, even with mild symptoms 1
• Shorter courses (5–7 days) are associated with higher failure rates in this age group and should not be used 1
• Complete the full course even if symptoms resolve earlier to minimize relapse and recurrence 5

When to Switch to Amoxicillin-Clavulanate

Switch to high-dose amoxicillin-clavulanate (90 mg/kg/day amoxicillin component + 6.4 mg/kg/day clavulanate, divided twice daily) if any of the following apply:

• The child received amoxicillin within the previous 30 days 1, 2
• No clinical improvement or worsening after 48–72 hours of amoxicillin therapy 1, 5
• Presence of concurrent purulent conjunctivitis (otitis-conjunctivitis syndrome suggesting H. influenzae) 1, 2
• Severe presentation at initial visit (moderate-to-severe otalgia or fever ≥39°C/102.2°F) 1

The rationale is that beta-lactamase-producing Haemophilus influenzae (34–62% of isolates) and Moraxella catarrhalis are resistant to amoxicillin alone but susceptible to amoxicillin-clavulanate 4, 1

Clinical Monitoring Protocol

• Reassess at 48–72 hours if symptoms worsen or fail to improve 1, 5
• Specific red flags requiring reassessment include:
  • Persistent or worsening ear pain
  • Continued high fever (≥38.5°C)
  • New otorrhea
  • Increased irritability 5
• If amoxicillin-clavulanate also fails, administer intramuscular ceftriaxone 50 mg/kg once daily for 3 consecutive days (superior to single-dose regimen) 1, 2

Pain Management

• Initiate weight-based acetaminophen or ibuprofen immediately at diagnosis, regardless of antibiotic decision 1, 5
• Analgesics provide symptomatic relief within 24 hours, whereas antibiotics provide no pain relief in the first 24 hours 1
• Continue analgesia throughout the acute phase (typically 3–7 days) 1

Expected Post-Treatment Course

• 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 1, 5
• This persistent effusion without acute symptoms represents otitis media with effusion (OME), not treatment failure, and requires only observation—not additional antibiotics 1, 5
• Routine follow-up visits are unnecessary for uncomplicated cases that improve clinically 5

Critical Pitfalls to Avoid

• Do not use standard-dose amoxicillin (40–45 mg/kg/day) in children under 2 years, as it fails to achieve adequate concentrations against resistant pneumococci 1, 3
• Do not prescribe trimethoprim-sulfamethoxazole or erythromycin-sulfisoxazole as second-line agents due to substantial pneumococcal resistance (>40% macrolide resistance) 1, 2
• Do not use shorter courses (5–7 days) in children under 6 years; full 10-day therapy is required 1, 5
• Do not treat isolated tympanic membrane redness without bulging or effusion, as this does not meet diagnostic criteria for bacterial AOM 1
• Antibiotics do not prevent complications: 33–81% of children who develop acute mastoiditis had received prior antibiotics 6, 1

Practical Administration Tips

• Using 400 mg/5 mL suspension: 6.2 mL twice daily provides approximately 496 mg per dose
• Using 250 mg/5 mL suspension: 10 mL twice daily provides 500 mg per dose
• Administer doses every 12 hours to maintain therapeutic middle ear fluid concentrations 2
• Verify suspension concentration before dispensing to avoid dosing errors 2