What is the recommended treatment for acute sinusitis in children, including supportive care, indications for antibiotics, first‑line antibiotic choice and alternatives for penicillin allergy, use of intranasal corticosteroids, and criteria for specialist referral?

Treatment of Acute Sinusitis in Children

Start amoxicillin 45 mg/kg/day divided twice daily for 10-14 days as first-line therapy when antibiotics are indicated, but only after confirming the diagnosis meets specific clinical criteria for bacterial sinusitis. 1

Diagnostic Criteria Before Treatment

Not every child with nasal discharge needs antibiotics—fewer than 1 in 15 children with a common cold develop true bacterial sinusitis. 2 The diagnosis requires meeting one of three specific patterns:

• Persistent symptoms: Nasal discharge or daytime cough lasting ≥10 days without any improvement 1, 3
• Severe symptoms: Fever ≥39°C for ≥3 consecutive days with thick, purulent nasal discharge 1, 3
• Worsening pattern ("double sickening"): Initial improvement from a viral cold followed by new fever or substantially worse nasal discharge/cough 1, 3

When to Start Antibiotics vs. Watchful Waiting

For children with persistent symptoms only (≥10 days without improvement), you have two evidence-based options: start antibiotics immediately or observe for an additional 3 days. 1, 3 Approximately 73-85% of these children improve spontaneously without antibiotics. 3

For children with severe symptoms or worsening pattern, start antibiotics immediately—do not observe. 1, 3

First-Line Antibiotic Choice

Amoxicillin 45 mg/kg/day divided twice daily (maximum 500 mg per dose) for 10-14 days. 1 This remains first-line due to effectiveness against Streptococcus pneumoniae, favorable safety profile, and low cost. 1

High-Risk Situations Requiring High-Dose Amoxicillin-Clavulanate

Use amoxicillin-clavulanate 80-90 mg/kg/day of the amoxicillin component with 6.4 mg/kg/day clavulanate divided twice daily for: 1, 4

• Recent antibiotic use (within past 30 days)
• Daycare attendance
• Age <2 years
• Moderate-to-severe symptoms at presentation
• Geographic areas with high penicillin-resistant S. pneumoniae rates (>10%)

Penicillin Allergy Alternatives

For true penicillin allergy, use cephalosporins (cefuroxime, cefpodoxime, or cefdinir) unless there is a history of severe IgE-mediated reaction. 5 For serious drug allergy, clarithromycin or azithromycin may be prescribed, though these are less effective. 5

Adjunctive Therapies That Work

Intranasal corticosteroids (mometasone, fluticasone, or budesonide twice daily) reduce inflammation and improve outcomes—use them. 1, 3 Multiple RCTs in adolescents and adults show significant benefit. 2

Saline nasal irrigation (not just spray—actual irrigation or lavage) improves nasal airflow and quality of life when combined with antibiotics. 2, 1

Analgesics/antipyretics (acetaminophen or ibuprofen) for symptomatic relief of pain and fever. 1, 3

Adjunctive Therapies to AVOID

Do not use antihistamines for acute bacterial sinusitis unless the child has documented allergic rhinitis with typical allergic symptoms. 2, 1 They have no role in treating bacterial sinusitis itself. 6

Do not use oral or topical decongestants or mucolytics—insufficient evidence of benefit. 2, 1 A Cochrane review found no appropriately designed studies supporting their use in children. 7

Monitoring and Treatment Failure

Reassess at 72 hours. If the child is worsening or showing no improvement: 1, 2

• Change to high-dose amoxicillin-clavulanate (90 mg/kg/day of amoxicillin component) if initially on amoxicillin alone 1
• Consider second-line options: cephalosporins or intramuscular ceftriaxone 1
• Reevaluate the diagnosis—is this truly bacterial sinusitis?

Red Flags Requiring Urgent Referral

Immediately refer or hospitalize for: 1, 2

• Orbital complications: Periorbital/orbital swelling, proptosis, impaired extraocular movements, vision changes
• CNS complications: Severe headache, photophobia, altered mental status, seizures, focal neurologic signs
• High fever unresponsive to antipyretics with toxic appearance

These children need contrast-enhanced CT of sinuses/orbits/head and intravenous antibiotics including vancomycin to cover methicillin-resistant S. pneumoniae. 2

Common Pitfalls to Avoid

Don't treat every child with colored nasal discharge. Thick, colored mucus frequently occurs with viral colds and does not by itself indicate bacterial sinusitis. 2 Wait for the specific diagnostic patterns described above.

Don't use imaging routinely. Plain radiographs, CT, and MRI should not be performed to differentiate bacterial sinusitis from viral URI. 2 Reserve CT for suspected complications or recurrent cases failing medical management. 8

Don't stop antibiotics too early. Treat for the full 10-14 days, or alternatively for 7 days after symptoms resolve (whichever ensures at least 10 days total). 2, 5