What is the recommended treatment for a patient with acute sinusitis?

Acute Sinusitis Treatment

First-Line Antibiotic Therapy

Amoxicillin-clavulanate 875 mg/125 mg twice daily for 5-10 days is the preferred first-line treatment for confirmed acute bacterial sinusitis in adults, providing superior coverage against β-lactamase-producing organisms. 1

When to Start Antibiotics

Antibiotics should only be prescribed when bacterial infection is confirmed by one of three clinical patterns: 1

• Persistent symptoms ≥10 days without improvement 1
• Severe symptoms (fever ≥39°C with purulent nasal discharge) for ≥3 consecutive days 1
• "Double sickening" - worsening after initial improvement from a viral upper respiratory infection 1, 2

Critical context: 98-99.5% of acute sinusitis is viral and resolves spontaneously within 7-10 days without antibiotics. 1

Standard Dosing Regimens

For uncomplicated cases: 1, 3

• Amoxicillin-clavulanate 875 mg/125 mg twice daily for 5-10 days 1
• Alternative: Amoxicillin 500 mg twice daily (mild disease) or 875 mg twice daily (moderate disease) 3

For high-risk patients (recent antibiotic use, age >65, moderate-to-severe symptoms, comorbidities): 1

• High-dose amoxicillin-clavulanate 2 g/125 mg twice daily 1

Treatment Duration

Treat for 5-10 days, or until symptom-free for 7 days (typically 10-14 days total). 1, 3 Shorter 5-7 day courses have comparable efficacy with fewer adverse effects. 1

Penicillin-Allergic Patients

Non-Anaphylactic Allergy

For non-Type I penicillin allergy (rash, mild reactions), use second- or third-generation cephalosporins - the risk of cross-reactivity is negligible. 1

Recommended options: 1, 3

• Cefuroxime-axetil (second-generation) 1
• Cefpodoxime-proxetil (third-generation) 1
• Cefdinir (third-generation) 1

All dosed for 10 days. 3

Severe Penicillin Allergy (Anaphylaxis)

For documented severe penicillin allergy, use respiratory fluoroquinolones as first-line therapy. 1, 4

• Levofloxacin 500-750 mg once daily for 10-14 days 1, 4
• Moxifloxacin 400 mg once daily for 10-14 days 1, 4

Critical pitfall: Never use azithromycin or other macrolides due to resistance rates exceeding 20-25% for both S. pneumoniae and H. influenzae. 1, 4

Second-Line Treatment for Failure

If no improvement after 3-5 days of initial therapy, switch to a respiratory fluoroquinolone. 1, 3

• Levofloxacin 500-750 mg once daily for 10-14 days 1
• Moxifloxacin 400 mg once daily for 10-14 days 1

These achieve 90-92% clinical efficacy against drug-resistant S. pneumoniae and β-lactamase-producing organisms. 1, 4

Alternative second-line option: 1

• High-dose amoxicillin-clavulanate 2 g/125 mg twice daily 1

Essential Adjunctive Therapies

Prescribe intranasal corticosteroids for all patients with acute bacterial sinusitis to reduce mucosal inflammation and improve drainage. 1, 5

• Mometasone, fluticasone, or budesonide twice daily 1
• Number needed to treat: 14 4
• Provides clinically important benefits with minimal systemic absorption 5

Additional supportive measures: 1, 6

• Saline nasal irrigation for mucus clearance 1, 6
• Analgesics (acetaminophen or NSAIDs) for pain 1, 6
• Short-term oral corticosteroids (5 days) for marked mucosal edema or treatment failure 1, 3

Critical Monitoring Timepoints

Reassess at 3-5 days: If no improvement, switch antibiotics or re-evaluate diagnosis. 1, 3

Reassess at 7 days: Confirm diagnosis if symptoms persist or worsen. 1, 3

When to Refer to Specialist

Refer to otolaryngology or infectious disease if: 1, 4

• No improvement after 7 days of appropriate second-line therapy 1
• Worsening symptoms at any time 1
• Suspected complications (orbital cellulitis, meningitis, abscess) 1, 4
• Recurrent sinusitis (≥3 episodes per year) 1

Pediatric Considerations

For children, use amoxicillin 45 mg/kg/day in 2 divided doses for standard therapy. 1

For high-risk children (age <2 years, daycare, recent antibiotics): 1

• High-dose amoxicillin 80-90 mg/kg/day in 2 divided doses 1

If no improvement at 72 hours, switch to high-dose amoxicillin-clavulanate (80-90 mg/kg/day of amoxicillin component with 6.4 mg/kg/day clavulanate in 2 divided doses). 1

Antibiotics to Avoid

Never use as first-line therapy: 1, 4

• First-generation cephalosporins (cephalexin) - inadequate H. influenzae coverage 4
• Azithromycin/macrolides - 20-25% resistance rates 1, 4, 7
• Trimethoprim-sulfamethoxazole - 50% resistance for S. pneumoniae 4
• Clindamycin monotherapy - no activity against H. influenzae or M. catarrhalis 4

Watchful Waiting Option

For uncomplicated acute bacterial sinusitis, watchful waiting without immediate antibiotics is appropriate when reliable follow-up can be assured. 1 Start antibiotics only if no improvement by 7 days or worsening at any time. 1