What is the appropriate Augmentin (amoxicillin/clavulanate) dose for a 33 kg child with acute sinusitis?

Augmentin Dosing for 33kg Child with Sinusitis

For a 33kg child with acute bacterial sinusitis, prescribe high-dose amoxicillin-clavulanate (Augmentin) at 90 mg/kg/day of the amoxicillin component, which equals approximately 2970 mg/day total, given as 1485 mg twice daily for 10-14 days. 1

Dose Calculation

For this 33kg child:

• Total daily dose: 90 mg/kg/day × 33 kg = 2970 mg amoxicillin component per day
• Divided dose: 1485 mg twice daily (every 12 hours)
• Clavulanate component: 6.4 mg/kg/day = 211 mg/day total
• Duration: 10-14 days (minimum 10 days, or 7 days after symptom resolution) 1

When to Use High-Dose Augmentin vs Standard Amoxicillin

The 2013 AAP guidelines provide clear criteria for choosing high-dose amoxicillin-clavulanate over standard amoxicillin 1:

Use high-dose Augmentin (80-90 mg/kg/day) if the child has ANY of these risk factors:

• Moderate to severe illness (high fever ≥39°C for ≥3 consecutive days with purulent nasal discharge)
• Age younger than 2 years
• Attends daycare/child care
• Recent antibiotic use (within past 4 weeks)
• Lives in area with high penicillin-resistant S. pneumoniae (>10% resistance)

Use standard amoxicillin (45 mg/kg/day) only if:

• Child is ≥2 years old
• Mild to moderate symptoms
• No daycare attendance
• No recent antibiotics
• Low local resistance rates

Clinical Context: When Antibiotics Are Indicated

Not all sinusitis requires antibiotics. The AAP guidelines distinguish three presentations 1:

1. Persistent sinusitis (most common): Nasal discharge or daytime cough lasting ≥10 days without improvement → May observe 3 more days OR treat
2. Severe sinusitis: Fever ≥39°C for ≥3 consecutive days with purulent nasal discharge → Treat immediately
3. Worsening sinusitis: Initial improvement then worsening with new fever or increased symptoms → Treat immediately

Evidence Supporting This Recommendation

The high-dose Augmentin recommendation is based on strong guideline evidence 1. A 2009 RCT demonstrated that high-dose amoxicillin-clavulanate (90 mg/kg amoxicillin with 6.4 mg/kg clavulanate) resulted in 50% cure rate vs 14% with placebo, with significantly fewer treatment failures (14% vs 68%) 2.

However, recent evidence shows nuance: A 2023 pediatric study found no difference in treatment failure between amoxicillin-clavulanate and amoxicillin alone (RR 0.98), though amoxicillin-clavulanate had higher rates of GI symptoms and yeast infections 3. This supports using plain amoxicillin when resistance risk is low, but the AAP guidelines still recommend Augmentin for children with risk factors given the serious potential complications of untreated resistant infections.

Practical Prescribing Details

For Augmentin ES-600 suspension (if using this formulation):

• This child would need approximately 12 mL twice daily 4
• Must be refrigerated and used within 10 days of reconstitution
• Give at start of meals to minimize GI side effects and enhance clavulanate absorption 4

Common pitfalls to avoid:

• Do not substitute different Augmentin formulations—they contain different clavulanate ratios and are NOT interchangeable 4
• Maximum single dose is 2000 mg amoxicillin component 1
• Do not use standard-dose formulations (200/28.5 or 400/57) when high-dose is indicated

Monitoring and Follow-up

• Reassess if no improvement by 72 hours
• Treatment failure warrants consideration of resistant organisms or complications
• Watch for adverse effects: diarrhea (most common), rash, yeast infections 3