Treatment Protocol for Acute Sinusitis
Diagnosis: Distinguish Viral from Bacterial Infection First
Before prescribing antibiotics, confirm acute bacterial rhinosinusitis (ABRS) using one of three patterns:
- Persistent symptoms ≥10 days without improvement: purulent nasal discharge plus nasal obstruction OR facial pain/pressure/fullness 1, 2
- Severe symptoms ≥3–4 consecutive days: fever ≥39°C (102.2°F) with purulent nasal discharge and facial pain 1, 2
- "Double sickening": initial improvement from a viral URI followed by worsening symptoms within 10 days 1, 2
Critical context: 98–99.5% of acute rhinosinusitis is viral and resolves spontaneously within 7–10 days without antibiotics 2, 3. Do not prescribe antibiotics for symptoms <10 days unless severe features are present 1, 2.
First-Line Antibiotic Therapy
Amoxicillin-clavulanate 875 mg/125 mg orally twice daily for 5–10 days is the preferred first-line regimen, providing 90–92% predicted clinical efficacy against Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis 1, 2. The clavulanate component is essential because 30–40% of H. influenzae and 90–100% of M. catarrhalis produce β-lactamase 2.
Treatment duration: Continue for 5–10 days or until symptom-free for 7 consecutive days (typically 10–14 days total) 1, 2, 4. Recent evidence supports shorter 5–7 day courses with comparable efficacy and fewer adverse effects 2, 4.
High-dose regimen (2 g/125 mg twice daily) is indicated when any of these risk factors are present: recent antibiotic use (≤4–6 weeks), age >65 years, daycare exposure, moderate-to-severe symptoms, comorbidities (diabetes, chronic cardiac/hepatic/renal disease), or immunocompromised state 2.
Alternatives for Penicillin Allergy
Non-severe (non-Type I) allergy: Second- or third-generation cephalosporins (cefuroxime-axetil, cefpodoxime-proxetil, cefdinir, cefprozil) for 10 days—cross-reactivity is negligible 1, 2.
Severe (Type I/anaphylactic) allergy: Respiratory fluoroquinolones are preferred:
- 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, 2.
Doxycycline 100 mg once daily for 10 days is an acceptable but suboptimal alternative (77–81% efficacy with 20–25% bacteriologic failure rate); reserve only when fluoroquinolones and cephalosporins are contraindicated 2.
Watchful Waiting Option
For uncomplicated ABRS with reliable follow-up, initial observation without antibiotics is appropriate 1, 5. Start antibiotics only if no improvement by day 7 or if symptoms worsen at any time 1, 2. The number needed to treat (NNT) with antibiotics is 10–15 to achieve one additional cure 2, 6.
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, 6.
Saline nasal irrigation 2–3 times daily provides symptomatic relief and aids mucus clearance 1, 2, 6.
Analgesics (acetaminophen or ibuprofen) for pain and fever control 1, 2, 6.
Decongestants (oral or topical); limit topical agents to ≤3 days to avoid rebound congestion 2, 6.
Monitoring and Reassessment Protocol
Reassess at 3–5 days: If no clinical improvement (persistent purulent drainage, unchanged facial pain, or worsening), switch immediately to high-dose amoxicillin-clavulanate OR a respiratory fluoroquinolone 2, 6.
Reassess at 7 days: Persistent or worsening symptoms require:
- Reconfirm ABRS diagnosis
- Exclude complications (orbital cellulitis, meningitis, intracranial abscess)
- Consider imaging (CT) only if complications suspected
- Refer to ENT if appropriate 1, 2, 6
Expected timeline: Noticeable improvement within 3–5 days; complete resolution by 10–14 days or when symptom-free for 7 consecutive days 2, 6.
Antibiotics to Avoid
Macrolides (azithromycin, clarithromycin): 20–25% resistance rates in S. pneumoniae and H. influenzae—explicitly contraindicated 2.
Trimethoprim-sulfamethoxazole: ≈50% resistance in S. pneumoniae and ≈27% in H. influenzae 2.
First-generation cephalosporins (cephalexin): Inadequate coverage since ~50% of H. influenzae strains produce β-lactamase 2.
Red-Flag Situations Requiring Urgent ENT Referral
- No improvement after 7 days of appropriate second-line antibiotic therapy 2, 6
- Any worsening of symptoms at any time (increasing facial pain, fever, purulent drainage) 2, 6
- Signs of complications: severe headache, visual changes, periorbital swelling/erythema, proptosis, diplopia, altered mental status, cranial nerve deficits 2, 6
- Recurrent sinusitis (≥3 episodes per year) suggesting underlying allergic rhinitis, immunodeficiency, or anatomic abnormalities 1, 2
Common Pitfalls to Avoid
Do not obtain routine imaging (X-ray or CT) for uncomplicated ABRS; up to 87% of viral URIs show sinus abnormalities on imaging, leading to unnecessary interventions 2.
Do not use fluoroquinolones as first-line therapy in patients without documented β-lactam allergy—reserve them to prevent resistance development 2.
Ensure adequate treatment duration (≥5 days for adults, ≥10 days for children) to prevent relapse 2, 4.
Gastrointestinal adverse effects with amoxicillin-clavulanate are common: diarrhea in 40–43% of patients; severe diarrhea in 7–8% 2, 6.