Does acute rhinosinusitis require antibiotic therapy?

Does a Sinus Infection Need Antibiotics?

Most sinus infections do not need antibiotics because 98–99.5% are viral and resolve spontaneously within 7–10 days without treatment. 1, 2

When Antibiotics Are NOT Indicated

• Do not prescribe antibiotics for symptoms lasting less than 10 days unless severe features are present (fever ≥39°C with purulent discharge for ≥3 consecutive days). 1, 2
• Purulent nasal discharge alone does not indicate bacterial infection—it reflects normal neutrophil activity in viral inflammation and should not trigger antibiotic therapy. 3
• The presence of rhinorrhea, cough, oral ulcers, and/or hoarseness strongly suggests viral etiology and argues against bacterial infection. 3

Three Clinical Patterns That Justify Antibiotics

Antibiotics should be prescribed only when acute bacterial rhinosinusitis (ABRS) is confirmed by at least one of these patterns: 1, 2

1. Persistent symptoms ≥10 days without improvement: purulent nasal discharge plus either nasal obstruction or facial pain/pressure/fullness 1, 2

2. Severe symptoms ≥3–4 consecutive days: fever ≥39°C with purulent nasal discharge and facial pain 1, 2

3. "Double sickening": initial improvement from a viral URI followed by new-onset fever, worsening nasal discharge, or markedly increased cough within 10 days 1, 2

First-Line Antibiotic Regimen

When antibiotics are indicated, amoxicillin-clavulanate 875 mg/125 mg twice daily for 5–10 days is the preferred first-line agent, providing 90–92% predicted clinical efficacy against the three major pathogens (Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis). 2

Why Amoxicillin-Clavulanate Over Plain Amoxicillin

• The clavulanate component is essential because 30–40% of H. influenzae and 90–100% of M. catarrhalis produce β-lactamase enzymes that inactivate plain amoxicillin. 2
• Plain amoxicillin may be used only for mild disease in patients who have not received antibiotics in the preceding 4–6 weeks. 2

Watchful Waiting Strategy

For patients meeting the persistent-symptom criterion (≥10 days), initial observation without antibiotics is appropriate when reliable follow-up can be ensured. 2, 4

• Start antibiotics only if there is no improvement by day 7 or if symptoms worsen at any time. 2
• The number needed to treat (NNT) with antibiotics is 10–15 to achieve one additional cure compared with placebo, reflecting the high rate of spontaneous recovery. 2

Essential Adjunctive Therapies (For All Patients)

These should be added regardless of whether antibiotics are prescribed: 2, 5

• Intranasal corticosteroids (mometasone, fluticasone, or budesonide) twice daily significantly reduce mucosal inflammation and accelerate symptom resolution—supported by strong evidence from multiple randomized controlled trials. 2
• Saline nasal irrigation 2–3 times daily provides symptomatic relief and aids mucus clearance. 2, 5
• Analgesics (acetaminophen or ibuprofen) for pain and fever control. 2, 3

Monitoring and Reassessment

• Reassess at 3–5 days of antibiotic therapy: if no clinical improvement (persistent purulent drainage, unchanged facial pain, or worsening), switch to high-dose amoxicillin-clavulanate (2 g/125 mg twice daily) or a respiratory fluoroquinolone (levofloxacin 500 mg once daily or moxifloxacin 400 mg once daily). 2
• Reassess at 7 days: persistent or worsening symptoms warrant confirmation of diagnosis, exclusion of complications (orbital cellulitis, meningitis, intracranial abscess), and consideration of imaging or ENT referral. 2

Alternatives for Penicillin Allergy

Non-Severe (Non-Type I) Penicillin Allergy

• Second- or third-generation cephalosporins (cefuroxime-axetil, cefpodoxime-proxetil, cefdinir, or cefprozil) for 10 days—cross-reactivity with penicillins is negligible (<1%). 2

Severe (Type I/Anaphylactic) Penicillin Allergy

• Respiratory fluoroquinolones are preferred: levofloxacin 500 mg once daily for 10–14 days or moxifloxacin 400 mg once daily for 10 days, both achieving 90–92% predicted efficacy against multidrug-resistant pathogens. 2

Common Pitfalls to Avoid

• Do not obtain routine imaging (X-ray or CT) for uncomplicated acute rhinosinusitis; up to 87% of viral upper-respiratory infections show sinus abnormalities on imaging, leading to unnecessary interventions. 2
• Avoid macrolides (azithromycin, clarithromycin) due to 20–25% resistance rates in S. pneumoniae and H. influenzae. 2
• Avoid trimethoprim-sulfamethoxazole due to ≈50% resistance in S. pneumoniae and ≈27% in H. influenzae. 2
• Ensure adequate treatment duration (≥5 days for adults) to prevent relapse. 2

Red-Flag Situations Requiring Urgent ENT Referral

• No improvement after 7 days of appropriate second-line antibiotic therapy 2
• Worsening symptoms at any point (increasing facial pain, fever, purulent drainage) 2
• Signs of complications: severe headache, visual changes, periorbital swelling/erythema, proptosis, diplopia, altered mental status, or cranial nerve deficits 2
• Recurrent sinusitis (≥3 episodes per year) suggesting underlying allergic rhinitis, immunodeficiency, or anatomic abnormalities 2