Management of Acute Bacterial Sinusitis in Adults
When to Prescribe Antibiotics
Antibiotics are indicated only when acute bacterial rhinosinusitis is confirmed by at least one of three specific clinical patterns:
- Persistent symptoms ≥10 days without improvement (purulent nasal discharge plus either nasal obstruction or facial pain/pressure/fullness). 1
- Severe symptoms ≥3–4 consecutive days with fever ≥39°C (102.2°F), purulent nasal discharge, and facial pain. 1
- "Double sickening": initial improvement from a viral upper respiratory infection followed by worsening symptoms within 10 days. 1
Critical context: Approximately 98–99.5% of acute rhinosinusitis cases are viral and resolve spontaneously within 7–10 days without antibiotics. 1 Do not prescribe antibiotics for symptoms lasting <10 days unless the severe criteria above are met. 1
First-Line Antibiotic Regimen
Amoxicillin-clavulanate 875 mg/125 mg orally twice daily for 5–10 days is the preferred first-line antibiotic for otherwise healthy adults with confirmed acute bacterial sinusitis. 1 This regimen provides 90–92% predicted clinical efficacy against the three major pathogens: Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis. 1
Treatment Duration
- Standard course: 5–10 days, or continue until the patient is symptom-free for 7 consecutive days (typically 10–14 days total). 1
- Shorter courses (5–7 days) provide comparable efficacy with fewer adverse effects and are increasingly recommended. 1, 2
High-Dose Regimen for Specific Risk Factors
Use high-dose amoxicillin-clavulanate (2 g/125 mg twice daily) when any of the following are present: 1
- Recent antibiotic use within the past 4–6 weeks
- Age >65 years
- Daycare exposure
- Moderate-to-severe symptoms
- Comorbidities (diabetes, chronic cardiac/hepatic/renal disease)
- Immunocompromised state
Alternatives for Penicillin Allergy
Non-Severe (Non-Type I) Penicillin Allergy
Use a second- or third-generation cephalosporin for 10 days (e.g., cefuroxime-axetil, cefpodoxime-proxetil, cefdinir, or cefprozil). 1 Cross-reactivity with penicillins is negligible (<1%). 1
Severe (Type I/Anaphylactic) Penicillin Allergy
Respiratory fluoroquinolones are the preferred first-line agents: 1
- Levofloxacin 500 mg once daily for 10–14 days, OR
- Moxifloxacin 400 mg once daily for 10 days
Both achieve 90–92% predicted efficacy against multidrug-resistant S. pneumoniae and β-lactamase-producing organisms. 1
Suboptimal Alternative
Doxycycline 100 mg once daily for 10 days is acceptable only when cephalosporins and fluoroquinolones are contraindicated (e.g., pregnancy, tendon disorders, QT-prolongation risk). 1 It offers lower predicted efficacy (77–81%) and a 20–25% bacteriologic failure rate due to limited activity against H. influenzae. 1
Watchful Waiting Strategy
For adults with uncomplicated acute bacterial sinusitis and reliable follow-up, initial observation without antibiotics is appropriate. 1 Initiate antibiotics only if there is no improvement by day 7 or if symptoms worsen at any time. 1 The number needed to treat (NNT) with antibiotics is 10–15 to achieve one additional cure compared with placebo. 1
Essential Adjunctive Therapies (Add to All Patients)
Intranasal corticosteroids (e.g., mometasone, fluticasone, budesonide) administered twice daily significantly reduce mucosal inflammation and accelerate symptom resolution. 1 This recommendation is supported by strong evidence from multiple randomized controlled trials. 1
- Saline nasal irrigation 2–3 times daily provides symptomatic relief and aids mucus clearance. 1
- Analgesics (acetaminophen or ibuprofen) for pain and fever control. 1
- Decongestants (oral or topical); limit topical agents to ≤3 days to avoid rebound congestion. 1
Monitoring and Reassessment
Early Reassessment (Days 3–5)
If there is no clinical improvement (persistent purulent drainage, unchanged facial pain, or worsening), switch promptly to: 1
- High-dose amoxicillin-clavulanate (875 mg/125 mg twice daily or 2 g/125 mg twice daily), OR
- A respiratory fluoroquinolone (levofloxacin or moxifloxacin)
Day 7 Reassessment
Persistent or worsening symptoms warrant: 1
- Confirmation of diagnosis
- Exclusion of complications (orbital cellulitis, meningitis, intracranial abscess)
- Imaging (CT) only if complications are suspected
- Referral to otolaryngology
Expected Timeline of Recovery
- Noticeable improvement should occur within 3–5 days of appropriate antibiotic therapy. 1
- Complete resolution typically occurs by 10–14 days or when the patient is symptom-free for 7 consecutive days. 1
Antibiotics to Avoid
- Macrolides (azithromycin, clarithromycin): 20–25% resistance rates in S. pneumoniae and H. influenzae. 1 The American Academy of Pediatrics explicitly contraindicates azithromycin for acute bacterial sinusitis. 1
- Trimethoprim-sulfamethoxazole: ≈50% resistance in S. pneumoniae and ≈27% in H. influenzae. 1
- First-generation cephalosporins (e.g., cephalexin): Inadequate coverage because ≈50% of H. influenzae strains produce β-lactamase. 1
Referral to Otolaryngology
Refer immediately if any of the following occur: 1
- No improvement after 7 days of appropriate second-line antibiotic therapy
- Worsening symptoms at any point during treatment
- Signs of complications (severe headache, visual changes, periorbital swelling/erythema, proptosis, diplopia, altered mental status, cranial nerve deficits)
- Recurrent sinusitis (≥3 episodes per year) requiring evaluation for underlying allergic rhinitis, immunodeficiency, or anatomic abnormalities
Critical Pitfalls to Avoid
- Do not prescribe antibiotics for symptoms <10 days unless severe features (fever ≥39°C with purulent discharge for ≥3 consecutive days) are present. 1
- Avoid routine imaging (X-ray or CT) for uncomplicated acute bacterial sinusitis; up to 87% of viral upper-respiratory infections show sinus abnormalities on imaging, leading to unnecessary interventions. 1
- Ensure adequate treatment duration (≥5 days for adults, ≥10 days for children) to prevent relapse. 1
- Reserve fluoroquinolones for severe penicillin allergy or treatment failure; avoid routine first-line use to limit resistance development. 1
- Gastrointestinal adverse effects with amoxicillin-clavulanate are common: diarrhea occurs in 40–43% of patients, with severe diarrhea in 7–8%. 1