What is the recommended dose of Augmentin (amoxicillin-clavulanate) for a 4-year-old child with sinusitis?

Augmentin Dosing for a 4-Year-Old with Sinusitis

For a 4-year-old child with acute bacterial sinusitis, prescribe high-dose amoxicillin-clavulanate (Augmentin) at 90 mg/kg/day of the amoxicillin component with 6.4 mg/kg/day of clavulanate, divided into 2 doses daily for 10-14 days. 1, 2

Why High-Dose Therapy for This Age Group

Children under 2 years are at higher risk for harboring resistant organisms, but the 4-year age group also benefits from high-dose therapy when there are risk factors. 1 The high-dose formulation effectively targets β-lactamase-producing H. influenzae and M. catarrhalis, as well as potentially resistant S. pneumoniae. 1

Risk factors that warrant high-dose therapy in a 4-year-old include:

• Recent antibiotic exposure within the past 30 days 1
• Daycare attendance 2, 3
• Severe infection presentation 2
• Geographic areas with high prevalence of resistant S. pneumoniae 2, 3

Specific Dosing Instructions

Use the 400 mg/57 mg per 5 mL oral suspension formulation for children aged 3 months and older. 4 For a typical 4-year-old weighing approximately 16-18 kg:

• Calculate the amoxicillin dose: 90 mg/kg/day = approximately 1440-1620 mg/day total
• Divide into 2 doses: approximately 720-810 mg per dose, given every 12 hours 1, 4
• Duration: Continue for 10-14 days 5, 1

The FDA label specifies that for sinusitis in children 12 weeks and older, the recommended dosing is 45 mg/kg/day every 12 hours using the 400 mg/5 mL formulation for standard therapy, but high-dose therapy (90 mg/kg/day) is preferred when resistance is a concern. 4

When to Use Standard-Dose Instead

Standard-dose amoxicillin alone (45 mg/kg/day in 2 divided doses) is acceptable only if the child has no risk factors for resistant organisms and uncomplicated disease. 2, 3 However, given the increasing prevalence of β-lactamase-producing organisms, most guidelines now favor starting with amoxicillin-clavulanate rather than plain amoxicillin. 5

Alternative for Vomiting or Non-Compliance

If the child is vomiting or cannot tolerate oral medication, give a single dose of ceftriaxone 50 mg/kg intramuscularly or intravenously. 5, 1 After clinical improvement at 24 hours, transition to oral amoxicillin-clavulanate to complete the 10-14 day course. 1

Monitoring and Treatment Failure Protocol

Reassess the child at 3-5 days after starting treatment. 5, 1 If no improvement is seen:

• Switch to a respiratory fluoroquinolone (though this is rarely used in young children) 5
• Consider ceftriaxone 50 mg/kg IM/IV daily 5, 2
• Re-evaluate the diagnosis for complications or alternative causes 5

If symptoms worsen at any time—especially with severe headache, high fever, eye swelling, or neurologic symptoms—immediately evaluate for orbital or intracranial complications. 5

Critical Pitfalls to Avoid

Do not substitute two 250 mg/125 mg tablets for one 500 mg/125 mg tablet, as they contain different amounts of clavulanate. 4 Always dose based on the amoxicillin component and ensure the clavulanate ratio is correct (6.4 mg/kg/day). 1

Do not use azithromycin or trimethoprim-sulfamethoxazole as alternatives, as resistance rates exceed 20-25% for both S. pneumoniae and H. influenzae. 5, 2

Ensure the full 10-14 day course is completed even if symptoms improve earlier, to prevent relapse and reduce the risk of developing resistance. 5, 3

Penicillin Allergy Alternatives

If the child has a documented penicillin allergy:

• For non-severe reactions: Use cefdinir, cefuroxime, or cefpodoxime 5, 2
• For severe Type I hypersensitivity: Avoid all β-lactams and consult with a specialist, as fluoroquinolones are generally avoided in young children 2