What antibiotics are recommended for treating bacterial sinus infections?

Antibiotic Treatment for Acute Bacterial Sinusitis

Amoxicillin-clavulanate 875 mg/125 mg twice daily for 5-10 days is the preferred first-line antibiotic for acute bacterial sinusitis in adults. 1, 2, 3

First-Line Treatment Selection

For most adults with uncomplicated maxillary sinusitis, start with amoxicillin-clavulanate 875 mg/125 mg twice daily for 5-10 days. 1, 2, 3 This combination provides superior coverage against beta-lactamase-producing organisms (H. influenzae and M. catarrhalis) that are increasingly prevalent. 3

• Plain amoxicillin 500 mg twice daily (mild disease) or 875 mg twice daily (moderate disease) remains acceptable only for uncomplicated cases without recent antibiotic exposure. 1, 2
• Treatment duration of 5-7 days has comparable efficacy to 10-14 days with fewer side effects. 1
• The standard recommendation is to treat until symptom-free for 7 days, typically totaling 10-14 days. 1

The choice between plain amoxicillin versus amoxicillin-clavulanate depends on recent antibiotic exposure and disease severity. 2 Use amoxicillin-clavulanate if the patient has received antibiotics within the past 4-6 weeks or has moderate-to-severe symptoms. 1, 3

Penicillin-Allergic Patients

For documented penicillin allergy, use second- or third-generation cephalosporins as first-line alternatives. 1, 2

• Second-generation: Cefuroxime 250-500 mg twice daily 1, 2
• Third-generation: Cefpodoxime 200-400 mg twice daily or cefdinir (standard dosing) 1, 2
• Recent evidence shows negligible risk of serious allergic reactions to second- and third-generation cephalosporins in penicillin-allergic patients. 1

Critical pitfall: Never use azithromycin or other macrolides for acute bacterial sinusitis due to 20-25% resistance rates among S. pneumoniae and H. influenzae. 1, 2 French and American guidelines explicitly exclude macrolides from recommended therapy. 1

Treatment Based on Anatomic Location

The anatomic site determines both antibiotic selection and urgency of treatment. 2, 3

Maxillary Sinusitis (Most Common)

• Use standard first-line antibiotics (amoxicillin-clavulanate or amoxicillin). 1, 2
• Symptoms include unilateral/bilateral infraorbital pain worsening when bending forward, pulsatile quality, peaking evening/night. 1

Frontal, Ethmoidal, or Sphenoidal Sinusitis

Reserve fluoroquinolones (levofloxacin 500 mg daily or moxifloxacin 400 mg daily) for these locations due to higher risk of major complications like meningitis or orbital involvement. 1, 2, 3 These sites require more aggressive treatment given proximity to critical structures. 1

Second-Line Treatment for Treatment Failure

If no improvement occurs within 3-5 days, switch antibiotics immediately. 1, 3

• First option: High-dose amoxicillin-clavulanate (if not already used) 3
• Second option: Respiratory fluoroquinolones:
  • Levofloxacin 750 mg daily for 5 days OR 500 mg daily for 10 days 1, 4
  • Moxifloxacin 400 mg daily for 10 days 1

Fluoroquinolones demonstrate 90-92% predicted clinical efficacy and 100% microbiologic eradication of S. pneumoniae, including multi-drug resistant strains (MDRSP). 1, 4 However, reserve them for treatment failures or complicated sinusitis to prevent resistance development. 1

Adjunctive Therapies

Add intranasal corticosteroids to antibiotic therapy for modest symptom relief (number needed to treat = 14). 1, 2, 3

Consider short-term oral corticosteroids (dexamethasone 4 mg) only for acute hyperalgic sinusitis (severe pain) or marked mucosal edema, always as adjunctive therapy with antibiotics, never as monotherapy. 1, 2, 3

Additional supportive measures include adequate hydration, analgesics, warm facial packs, and sleeping with head elevated. 1

Pediatric Dosing

For children, use amoxicillin 45 mg/kg/day in 2 divided doses for standard therapy. 1, 2

In areas with high prevalence of resistant S. pneumoniae or for children with risk factors (age <2 years, daycare attendance, recent antibiotic use), use high-dose amoxicillin 80-90 mg/kg/day in 2 divided doses. 1, 3

For children with risk factors, use amoxicillin-clavulanate 80-90 mg/kg/day (amoxicillin component) with 6.4 mg/kg/day clavulanate in 2 divided doses. 1, 3

For penicillin-allergic children, cefpodoxime proxetil 8 mg/kg/day in two doses is recommended. 1

Critical Pitfalls to Avoid

• Never use first-generation cephalosporins (cephalexin, cefadroxil)—they lack adequate coverage for H. influenzae. 2
• Do not prescribe antibiotics for viral upper respiratory infections lasting <10 days without bacterial features. 2
• Ensure adequate treatment duration (minimum 5 days, typically 7-10 days) to prevent relapse. 1
• Complete the full antibiotic course even after symptoms improve. 1
• Reassess at 3 days (pediatrics) or 7 days (adults) if no improvement to avoid treatment failure. 1

When to Consider Watchful Waiting

For adults with uncomplicated acute bacterial sinusitis, watchful waiting without immediate antibiotics is appropriate when follow-up can be assured, with antibiotics started if no improvement by 7 days or worsening at any time. 1

Recurrent Sinusitis

For patients with recurrent sinusitis (≥3 episodes per year), evaluate for underlying factors including allergic rhinitis, immunodeficiency, or anatomic abnormalities, and consider referral to an allergist-immunologist or otolaryngologist. 1, 3