Acute Sinusitis Treatment Guidelines
Distinguish Viral from Bacterial Sinusitis First
Most acute sinusitis (98–99.5%) is viral and resolves spontaneously within 7–10 days without antibiotics—reserve antibiotics only for confirmed acute bacterial rhinosinusitis (ABRS). 1
Diagnose ABRS when at least one of these patterns is present:
- Persistent symptoms ≥10 days without improvement (purulent nasal discharge plus 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 URI followed by worsening symptoms within 10 days 1
Do not prescribe antibiotics for symptoms <10 days unless severe criteria are met. 1
First-Line Antibiotic Therapy for ABRS
Amoxicillin-clavulanate 875 mg/125 mg orally twice daily for 5–10 days is the preferred first-line antibiotic for adults with confirmed ABRS, providing 90–92% predicted clinical efficacy against the three major pathogens (Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis). 1, 2
Dosing Specifications
- Standard dose: 875 mg/125 mg twice daily for most adults 1, 2
- High-dose regimen (2 g/125 mg twice daily) for patients with: 1, 2
- Recent antibiotic use within past 4–6 weeks
- Age >65 years
- Daycare attendance or close contact with daycare children
- Moderate-to-severe symptoms
- Comorbidities (diabetes, chronic cardiac/hepatic/renal disease)
- Immunocompromised state
Treatment Duration
- 5–10 days or until symptom-free for 7 consecutive days (typically 10–14 days total) 1, 2
- Recent evidence supports shorter 5–7 day courses with comparable efficacy and fewer adverse effects 1, 2
Watchful Waiting as Initial Strategy
For uncomplicated ABRS with reliable follow-up, watchful waiting without immediate antibiotics is equally appropriate—start antibiotics only if no improvement by day 7 or symptoms worsen at any time. 1, 3
- Number needed to treat (NNT) with antibiotics is 10–15 to achieve one additional cure over placebo 1, 2
- Approximately 73–85% of patients improve by day 7 even without antibiotics 2
Alternatives for Penicillin Allergy
Non-Severe (Non-Type I) Penicillin Allergy
Use second- or third-generation cephalosporins for 10 days—cross-reactivity with penicillin is negligible. 1, 2
Severe (Type I/Anaphylactic) Penicillin Allergy
Use respiratory fluoroquinolones with 90–92% predicted efficacy against multidrug-resistant pathogens. 1, 2
Suboptimal Alternative
- Doxycycline 100 mg once daily for 10 days (predicted efficacy only 77–81% with 20–25% bacteriologic failure rate due to limited H. influenzae coverage) 1, 2
Essential Adjunctive Therapies (Add to All Patients)
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. 1, 2
- Saline nasal irrigation 2–3 times daily for symptomatic relief and mucus clearance 1, 2
- Analgesics (acetaminophen or ibuprofen) for pain and fever control 1, 2
- Decongestants (oral or topical)—limit topical use to ≤3 days to avoid rebound congestion 1
Monitoring and Reassessment Protocol
Early Reassessment (Days 3–5)
If no clinical improvement by days 3–5, switch immediately to high-dose amoxicillin-clavulanate or a respiratory fluoroquinolone. 1, 2
- Only 30–41% of patients show improvement by days 3–5; zero improvement indicates treatment failure 2
Day 7 Reassessment
If symptoms persist or worsen by day 7, reconfirm the diagnosis, exclude complications (orbital cellulitis, meningitis, intracranial abscess), and consider imaging or ENT referral. 1, 2
- By day 7, most patients (73–85%) should demonstrate significant improvement 2
Signs Requiring Urgent Evaluation
- Worsening symptoms at any time (increasing pain, fever, purulent drainage) 1, 2
- Severe headache, visual changes, periorbital swelling/erythema 1, 2
- Altered mental status, cranial nerve deficits 1, 2
Antibiotics to Avoid
Never use these agents as first-line therapy for ABRS:
- Macrolides (azithromycin, clarithromycin): 20–25% resistance rates for S. pneumoniae and H. influenzae 1, 2
- Trimethoprim-sulfamethoxazole: 50% resistance in S. pneumoniae, 27% in H. influenzae 1, 2
- First-generation cephalosporins (cephalexin): inadequate coverage against H. influenzae (≈50% produce β-lactamase) 2
Pediatric Dosing Considerations
- Standard-dose amoxicillin: 45 mg/kg/day divided twice daily 1, 2
- High-dose amoxicillin: 80–90 mg/kg/day divided twice daily for children <2 years, daycare attendance, or recent antibiotic use 1, 2
- High-dose amoxicillin-clavulanate: 80–90 mg/kg/day (amoxicillin component) with 6.4 mg/kg/day clavulanate divided twice daily 1, 2
- Treatment duration: minimum 10–14 days for children (longer than adult courses) 1, 2
- Reassess at 72 hours; switch to high-dose amoxicillin-clavulanate if no improvement 1, 2
When to Refer to Otolaryngology
Refer immediately if any of the following occur:
- No improvement after 7 days of appropriate second-line antibiotic therapy 1, 2
- Worsening symptoms at any point during treatment 1, 2
- Suspected complications (orbital cellulitis, meningitis, intracranial abscess) 1, 2
- Recurrent sinusitis (≥3 episodes per year) requiring evaluation for underlying allergic rhinitis, immunodeficiency, or anatomic abnormalities 1, 2
Critical Pitfalls to Avoid
- Do not obtain routine imaging (X-ray or CT) for uncomplicated ABRS—87% of viral URIs show sinus abnormalities on imaging, leading to unnecessary interventions 1, 2
- Do not use fluoroquinolones as first-line therapy in patients without documented β-lactam allergy—reserve them to prevent resistance development 1, 2
- Ensure minimum treatment duration (≥5 days for adults, ≥10 days for children) to prevent relapse 1, 2
- Gastrointestinal adverse effects are common with amoxicillin-clavulanate (diarrhea in 40–43% of patients; severe diarrhea in 7–8%) 1, 2
- Do not extend therapy beyond 7 days without clinical justification—this increases adverse effects without improving outcomes 2