Suspected Acute Bacterial Sinusitis

Clinical definition:

Acute bacterial infection of para-nasal sinuses. Common bacterial pathogens include S. pneumoniae, H. influenzae, and M. catarrhalis. Symptoms include a preceding upper respiratory tract infection, fever, nasal congestion, nasal discharge, facial pain and tenderness. Uncommon in children, particularly in young children in whom sinuses are not fully developed.


Infant, Child & Adolescent

Preferred antibiotic choice
Amoxicillin (PO)APowder for oral liquid: 125 mg (as trihydrate) /5 mL; 250 mg (as trihydrate) /5 mL; Solid oral dosage form: 250 mg; 500 mg (as trihydrate)40 – 45 mg/kg/dose 12 hourly, maximum dose 1.5 g 12 hourly5 – 7 days
For patients who received amoxicillin in the previous 30 days, or for those who are non-responsive to first-line treatment with amoxicillin after 48 – 72 hours.
Amoxicillin + clavulanic acid (PO)AOral liquid: 125 mg amoxicillin + 31.25 mg clavulanic acid/5 mL; 250 mg amoxicillin + 62.5 mg clavulanic acid/5 mL; Tablet: 500 mg (as trihydrate) + 125 mg (as potassium salt).40 – 45 mg/kg of amoxicillin component per dose 12 hourly, maximum dose of amoxicillin component: 875 mg 12 hourly. (Refer to Other NotesB below for guidance on dosing accurately)5 – 7 days
In case of confirmed drug allergy or medical contraindication
Azithromycin (PO)COral liquid: 200 mg/5 mL; Capsule: 250 mg; 500 mg (anhydrous).10 mg/kg once daily, maximum dose 500 mg daily5 days


Principles of Stewardship:

  • Practice watchful waiting and withhold antibiotics except for patients with severe symptoms. For severe cases or poor response to initial therapy, expert advice and radiological imaging may be required to exclude intracranial extension.


A. If a patient cannot tolerate oral antibiotics (e.g. persistent vomiting), IV or IM antibiotics may be considered:

  • Ampicillin (25 mg/kg/dose 6 hourly, Maximum dose: 500 mg 6 hourly), or
  • Ceftriaxone (50 mg/kg/dose once daily, Maximum dose: 1 g)

B. Current widely available oral liquid formulations contain amoxicillin + clavulanic acid in a 4:1 ratio. To achieve 40-45 mg/kg/dose of amoxicillin component, when using the 4:1 formulation, prescribe amoxicillin + clavulanic acid 10-15 mg/kg/dose of amoxicillin component 12 hourly and separately prescribe amoxicillin 30-35 mg/kg/dose 12 hourly in order not to exceed the maximum recommended dose of clavulanic acid (10 mg/kg/day) thereby reducing the risk of antibiotic-associated diarrhoea. If oral liquid formulations with a higher dose of amoxicillin are available (7:1 ratio – 400 mg amoxicillin + 57.5 mg clavulanic acid/5 mL, or 14:1 ratio – 600 mg amoxicillin + 42.9 mg clavulanic acid/5 mL), these may be dosed at 40-45 mg/kg dose of amoxicillin component 12 hourly without a separate amoxicillin prescription (the clavulanic acid dose will not be exceeded). If the 7:1 ratio tablet formulation is available (875 mg amoxicillin + 125 mg clavulanic acid) it may be prescribed 12 hourly for children weighing 25 kg or more.

C. If patient fails macrolide therapy, consider ceftriaxone or refer to a specialist.