What is the first line treatment for sinusitis?

First-Line Treatment for Sinusitis

Amoxicillin-clavulanate 875 mg/125 mg twice daily for 7-10 days is the preferred first-line antibiotic for acute bacterial sinusitis in adults, but antibiotics should only be started when symptoms persist ≥10 days without improvement, severe symptoms last ≥3 consecutive days, or "double sickening" occurs after initial improvement. 1, 2

When to Start Antibiotics vs. Symptomatic Treatment

Most acute rhinosinusitis (98-99.5%) is viral and resolves spontaneously within 7-10 days without antibiotics. 1, 3 For symptoms lasting less than 10 days, start with over-the-counter symptomatic treatment only:

• Oral analgesics (acetaminophen or NSAIDs) for pain and fever relief 1, 3
• Oral decongestants (pseudoephedrine) for nasal congestion 1, 3
• Intranasal corticosteroids (mometasone, fluticasone, or budesonide) to reduce mucosal inflammation 1, 3
• Saline nasal irrigation for symptomatic relief and drainage 1, 3
• Topical decongestants for ≤3 days maximum to avoid rhinitis medicamentosa (rebound congestion) 2, 3

Diagnostic Criteria for Bacterial Sinusitis Requiring Antibiotics

Start antibiotics only when one of these three patterns is present: 1, 2

1. Persistent symptoms ≥10 days without clinical improvement (nasal discharge, congestion, facial pain/pressure) 1, 2
2. Severe symptoms for ≥3 consecutive days: fever ≥39°C (102.2°F) with purulent nasal discharge and facial pain 1, 2
3. "Double sickening": worsening symptoms after initial improvement from a viral upper respiratory infection 1, 2

First-Line Antibiotic Selection

For most adults with confirmed acute bacterial sinusitis: 1, 2

• Amoxicillin-clavulanate 875 mg/125 mg twice daily for 7-10 days is preferred due to increasing prevalence of β-lactamase-producing organisms (H. influenzae and M. catarrhalis) 1, 2
• Plain amoxicillin 500 mg twice daily (mild disease) or 875 mg twice daily (moderate disease) remains acceptable for uncomplicated cases without recent antibiotic exposure 1, 2

The clavulanate component provides critical coverage against β-lactamase-producing Haemophilus influenzae and Moraxella catarrhalis, which have become increasingly prevalent. 1

Treatment Duration

• Standard duration: 7-10 days until symptom-free for 7 days (typically 10-14 days total) 1, 2
• Some cephalosporins (cefuroxime-axetil, cefpodoxime-proxetil) are effective in 5-day courses 1, 2
• Reassess at 3-5 days: if no improvement, switch antibiotics or re-evaluate diagnosis 1, 2

Penicillin-Allergic Patients

For documented penicillin allergy (non-anaphylactic reactions like rash): 1, 2

• Second-generation cephalosporins: cefuroxime-axetil 1, 2
• Third-generation cephalosporins: cefpodoxime-proxetil, cefdinir, or cefprozil 1, 2

The risk of cross-reactivity between penicillins and second/third-generation cephalosporins is negligible for non-Type I allergies. 1

For severe penicillin allergy (anaphylaxis/Type I hypersensitivity): 1

• Respiratory fluoroquinolones: levofloxacin 500 mg once daily or moxifloxacin 400 mg once daily for 10 days 1, 4
• Reserve fluoroquinolones for this specific indication to prevent resistance development 1, 2

Second-Line Treatment for Treatment Failure

If no improvement after 3-5 days of initial therapy: 1, 2

• Switch to high-dose amoxicillin-clavulanate (4 g amoxicillin/250 mg clavulanate per day) for 10-14 days 1
• Or switch to respiratory fluoroquinolones: levofloxacin 500-750 mg once daily or moxifloxacin 400 mg once daily for 10 days, which provide 90-92% predicted clinical efficacy 1, 4

Adjunctive Therapies to Enhance Recovery

• Intranasal corticosteroids as adjunct to antibiotic therapy reduce mucosal inflammation and improve symptom resolution 1, 2
• Short-term oral corticosteroids (5 days) may be reasonable for patients with marked mucosal edema or who fail initial treatment 1, 2
• Adequate hydration, warm facial packs, sleeping with head elevated provide supportive relief 1

Critical Pitfalls to Avoid

• Never use azithromycin or other macrolides as first-line therapy due to 20-25% resistance rates for S. pneumoniae and H. influenzae 1, 5
• Never use first-generation cephalosporins (cephalexin) due to inadequate coverage against H. influenzae (50% β-lactamase producing) 1
• Never use topical decongestants >3 days due to risk of rhinitis medicamentosa 2, 3
• Never prescribe antibiotics for viral rhinosinusitis lasting <10 days unless severe symptoms are present—this contributes to antimicrobial resistance without clinical benefit 1, 3
• Inadequate treatment duration leads to relapse—complete the full 7-10 day course even after symptoms improve 1, 2
• Do not use fluoroquinolones as routine first-line therapy—reserve for treatment failures, severe penicillin allergy, or complicated sinusitis to prevent resistance 1, 2

When to Refer to a Specialist

Refer to otolaryngology when: 1

• Symptoms refractory to two courses of appropriate antibiotics 1
• Recurrent sinusitis (≥3 episodes per year) 1
• Suspected complications (orbital cellulitis, meningitis, intracranial sepsis) 1
• Need for sinus aspiration/culture in immunocompromised patients 1