Management of Acute Sinusitis in Adults
For an adult with acute sinusitis, distinguish viral from bacterial infection first: if symptoms persist ≥10 days without improvement, prescribe amoxicillin-clavulanate 875 mg/125 mg twice daily for 5–10 days, and add intranasal corticosteroids plus saline irrigation to all patients regardless of antibiotic use. 1
Step 1: Confirm the Diagnosis – Is This Bacterial or Viral?
98–99.5% of acute sinus infections are viral and resolve spontaneously within 7–10 days without antibiotics. 1 You must meet at least one of three patterns to diagnose acute bacterial rhinosinusitis (ABRS):
- Persistent symptoms ≥10 days with purulent nasal discharge plus either nasal obstruction or facial pain/pressure/fullness, without improvement 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 cold followed by worsening symptoms within 10 days 1
If symptoms are <10 days and not worsening, this is viral rhinosinusitis—do not prescribe antibiotics. 1, 2 Purulent nasal discharge alone does not indicate bacterial infection; it reflects neutrophilic inflammation common to viral disease. 1
Step 2: First-Line Antibiotic Therapy (When Bacterial Criteria Are Met)
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, 3 The clavulanate component is essential because 30–40% of H. influenzae and 90–100% of M. catarrhalis produce β-lactamase. 1, 4
When to Use High-Dose Amoxicillin-Clavulanate (2 g/125 mg Twice Daily)
Use the high-dose regimen if any of the following risk factors are present: 1, 3
- Recent antibiotic use within the past 4–6 weeks
- Age >65 years
- Daycare exposure (patient or close contact)
- Moderate-to-severe symptoms
- Comorbidities (diabetes, chronic cardiac/hepatic/renal disease)
- Immunocompromised state
Treatment Duration
- Standard course: 5–10 days, or continue until symptom-free for 7 consecutive days (typically 10–14 days total) 1, 3
- Shorter 5–7 day courses provide comparable efficacy with fewer adverse effects and are increasingly recommended 1, 5
- Ensure a minimum of 5 days to prevent relapse 1
Step 3: Alternatives for Penicillin Allergy
Non-Severe (Non-Type I) Penicillin Allergy (e.g., Mild Rash)
Use a second- or third-generation cephalosporin for 10 days—cross-reactivity is negligible: 1
- Cefuroxime-axetil
- Cefpodoxime-proxetil
- Cefdinir
- Cefprozil
Severe (Type I/Anaphylactic) Penicillin Allergy
Use a respiratory fluoroquinolone, which provides 90–92% predicted efficacy against multidrug-resistant S. pneumoniae: 1, 3
- Levofloxacin 500 mg once daily for 10–14 days, or
- Moxifloxacin 400 mg once daily for 10 days
Reserve fluoroquinolones for documented severe β-lactam allergy or treatment failure to prevent resistance development. 1
Suboptimal Alternative: Doxycycline
Doxycycline 100 mg once daily for 10 days is acceptable but yields only 77–81% predicted efficacy with a 20–25% bacteriologic failure rate due to limited H. influenzae coverage. 1, 3 Use only when cephalosporins and fluoroquinolones are contraindicated.
Step 4: Watchful Waiting (When Appropriate)
For uncomplicated ABRS with reliable follow-up, initial observation without antibiotics is appropriate. 1 Start antibiotics only if:
- No improvement by day 7, or
- Symptoms worsen at any time 1
The number needed to treat (NNT) with antibiotics is 10–15 to achieve one additional cure, reflecting the high rate of spontaneous recovery. 1
Step 5: Essential Adjunctive Therapies (Add to All Patients)
Intranasal Corticosteroids (Strongest Evidence)
Prescribe mometasone, fluticasone, or budesonide nasal spray twice daily to reduce mucosal inflammation and accelerate symptom resolution—supported by strong evidence from multiple randomized controlled trials. 1, 3, 2
Saline Nasal Irrigation
Perform 2–3 saline rinses daily to clear mucus and provide immediate symptomatic relief. 1, 2
Analgesics
Administer acetaminophen or ibuprofen as needed for facial pain, headache, and fever. 1
Decongestants (Use with Caution)
Oral pseudoephedrine or topical oxymetazoline may alleviate severe congestion, but limit topical agents to ≤3 days to avoid rebound congestion. 1, 2
Step 6: Monitoring and Reassessment
Early Reassessment (Days 3–5)
If no clinical improvement (persistent purulent drainage, unchanged facial pain, or worsening), switch immediately to: 1, 3
- High-dose amoxicillin-clavulanate (875 mg/125 mg or 2 g/125 mg twice daily), or
- A respiratory fluoroquinolone (levofloxacin or moxifloxacin)
Worsening at any time (new fever, increasing pain, periorbital swelling, visual changes, severe headache, altered mental status) mandates urgent evaluation for complications. 1
Day 7 Reassessment
Persistent or worsening symptoms should prompt: 1
- Confirmation of diagnosis
- Exclusion of complications (orbital cellulitis, meningitis, intracranial abscess)
- Imaging (CT) only if complications are suspected—routine imaging is not recommended 1, 2
Expected Timeline of Recovery
- Noticeable improvement within 3–5 days of appropriate antibiotic therapy 3, 6
- Complete symptom resolution by 10–14 days or when symptom-free for 7 consecutive days 1, 3
- Only 30–41% of patients achieve improvement by days 3–5; zero improvement at this stage indicates likely treatment failure 3
Step 7: Antibiotics to Avoid
- Macrolides (azithromycin, clarithromycin): 20–25% resistance rates in S. pneumoniae and H. influenzae 1, 3
- Trimethoprim-sulfamethoxazole: 50% resistance in S. pneumoniae and 27% in H. influenzae 1, 3
- First-generation cephalosporins (cephalexin): inadequate against H. influenzae because ~50% of strains produce β-lactamase 1, 3
Step 8: When to Refer 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
- Suspected 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
Common 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, 2
- 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 1, 2
- Do not use fluoroquinolones as first-line therapy in patients without documented β-lactam allergy to prevent resistance development 1
- Gastrointestinal adverse effects with amoxicillin-clavulanate are common: diarrhea in 40–43% of patients; severe diarrhea in 7–8% 1, 3
- Ensure adequate treatment duration (≥5 days for adults) to prevent relapse 1