What is the treatment for a sinus infection?

Treatment for Sinus Infection

Amoxicillin is the first-line antibiotic for acute bacterial sinusitis in adults at 500 mg twice daily (or 875 mg twice daily for severe infections) for 10-14 days, combined with intranasal corticosteroids as adjunctive therapy. 1, 2

When to Start Antibiotics

Not all sinus infections require antibiotics. Start antibiotics when you identify one of these three clinical presentations:

• Persistent symptoms: Nasal discharge/congestion or cough lasting >10 days without improvement 3
• Severe onset: High fever (≥39°C) with purulent nasal discharge for 3-4 consecutive days 3
• Worsening course: Initial improvement followed by worsening of symptoms ("double-sickening") 3

First-Line Antibiotic Treatment

Standard Therapy

• Amoxicillin 500 mg twice daily for most patients with acute bacterial sinusitis 1
• Amoxicillin 875 mg twice daily for more severe infections 1
• Duration: 10-14 days, or until symptom-free for 7 days 1, 2

For Penicillin Allergy

If truly allergic to penicillin, use cephalosporins as alternatives:

• Cefuroxime, cefpodoxime, cefprozil, or cefdinir 1, 2
• Some cephalosporins effective in 5-day courses 2

Critical caveat: Do NOT use azithromycin or clarithromycin for penicillin-allergic patients due to significant resistance of Streptococcus pneumoniae and Haemophilus influenzae to macrolides 1

Second-Line Treatment (Treatment Failure)

If no improvement after 3-5 days of initial therapy, switch to:

• Amoxicillin-clavulanate (high-dose: 90 mg/kg amoxicillin component with 6.4 mg/kg clavulanate, not exceeding 2g every 12 hours in adults) 1, 2
• This provides better coverage against beta-lactamase-producing organisms 1

Treatment Based on Sinus Location

Maxillary Sinusitis (Most Common)

• Use standard first-line antibiotics (amoxicillin or amoxicillin-clavulanate) 1

Frontal, Ethmoidal, or Sphenoidal Sinusitis

• Consider fluoroquinolones (levofloxacin or moxifloxacin) due to higher risk of complications 1, 2
• Reserve fluoroquinolones for these complicated cases only to prevent resistance development 1

Essential Adjunctive Therapies

Intranasal Corticosteroids

• Recommended for all patients with acute sinusitis as adjunct to antibiotics 1, 2
• Reduces mucosal inflammation and promotes drainage 2

Short-Term Oral Corticosteroids

• Consider when patient fails initial treatment, has marked mucosal edema, or nasal polyps 1, 2
• Particularly useful in acute hyperalgic sinusitis (severe pain) 1

Nasal Decongestants

• Oxymetazoline may help reduce congestion and improve drainage 2
• Limit to 5 days maximum to avoid rebound congestion (rhinitis medicamentosa) 2

Supportive Care

• Adequate hydration, analgesics for pain, warm facial packs, steamy showers, sleeping with head elevated 1, 2

Common Pitfalls to Avoid

• Overdiagnosis: Most upper respiratory infections are viral and do not require antibiotics 2
• Using macrolides: Azithromycin and clarithromycin should NOT be used due to resistance patterns 1, 4
• Inadequate duration: Complete the full 10-14 day course even after symptoms improve to prevent relapse 1
• Overusing fluoroquinolones: Reserve levofloxacin/moxifloxacin for complicated cases or treatment failures only 1
• Extended decongestant use: Never use topical decongestants >5 days 2

When to Refer to Specialist

Refer when encountering:

• Sinusitis refractory to usual antibiotic treatment 1
• Recurrent sinusitis (≥3 episodes per year) 1
• Need to clarify allergic or immunologic basis 1
• Sinusitis associated with unusual opportunistic infections 1