What is the treatment for a sinus infection?

Treatment of Acute Bacterial Sinusitis

Amoxicillin 500 mg twice daily for 10-14 days is the first-line treatment for most adults with acute bacterial sinusitis, with treatment continuing until symptom-free for 7 days. 1

Confirming the Diagnosis Before Treatment

Before initiating antibiotics, ensure the diagnosis meets criteria for acute bacterial sinusitis—not just viral rhinosinusitis 2:

• Persistent symptoms ≥10 days without improvement (nasal discharge, congestion, facial pain/pressure, or cough) 1, 2
• Severe symptoms for ≥3 consecutive days (fever >39°C with purulent nasal discharge and facial pain) 1, 2
• "Double sickening" pattern: initial improvement from viral URI followed by worsening symptoms 1, 2

Most cases of acute rhinosinusitis are viral and resolve within 7 days without antibiotics 2. Overdiagnosis leads to unnecessary antibiotic use and resistance 2.

First-Line Antibiotic Selection

Standard Therapy (Uncomplicated Cases)

• Amoxicillin 500 mg twice daily for mild disease without recent antibiotic exposure 1, 2
• Amoxicillin 875 mg twice daily for moderate severity or areas with resistant S. pneumoniae 1, 2
• Duration: 10-14 days or until symptom-free for 7 days 1, 2

High-Risk or Severe Cases

Amoxicillin-clavulanate 875 mg/125 mg twice daily is preferred for 1, 2:

• Recent antibiotic use within 4-6 weeks
• Severe symptoms at presentation
• Age <2 years or >65 years
• Daycare attendance (children)
• Areas with high prevalence of β-lactamase-producing organisms

The clavulanate component provides essential coverage against β-lactamase-producing H. influenzae and M. catarrhalis, which have become increasingly prevalent 1.

Penicillin-Allergic Patients

Second- or third-generation cephalosporins are the preferred alternatives due to negligible cross-reactivity risk 1, 2:

• Cefuroxime-axetil (second-generation): standard alternative 1, 2
• Cefpodoxime-proxetil (third-generation): superior activity against H. influenzae 1, 2
• Cefdinir (third-generation): excellent coverage 1, 2

For severe β-lactam allergy, use respiratory fluoroquinolones 1:

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

Critical caveat: Azithromycin and other macrolides should NOT be used due to 20-25% resistance rates in S. pneumoniae and H. influenzae 1. Doxycycline has 20-25% predicted bacteriologic failure and limited activity against H. influenzae 1.

Treatment Failure Protocol

If no improvement after 3-5 days, reassess and switch antibiotics 1, 2:

1. Switch to amoxicillin-clavulanate 875 mg/125 mg twice daily if started on plain amoxicillin 1, 2
2. Switch to respiratory fluoroquinolone (levofloxacin or moxifloxacin) if already on amoxicillin-clavulanate 1
3. Consider imaging (CT sinuses) to confirm diagnosis and rule out complications 1

Fluoroquinolones provide 90-92% predicted clinical efficacy and excellent coverage against multi-drug resistant S. pneumoniae 1.

Anatomic Location Considerations

• Maxillary sinusitis (most common): standard first-line antibiotics as above 1
• Frontal, ethmoidal, or sphenoidal sinusitis: consider starting with fluoroquinolones due to risk of serious complications (orbital cellulitis, meningitis, brain abscess) 1, 2

Adjunctive Therapies (Always Recommended)

Intranasal corticosteroids are the cornerstone adjunct 1, 2:

• Reduce inflammation and mucosal edema
• Improve sinus drainage
• May decrease need for antibiotics
• Continue throughout antibiotic course

Supportive measures 1, 2:

• Saline nasal irrigation (hypertonic preferred for better mucociliary clearance) 3
• Analgesics (acetaminophen or NSAIDs) for pain 1
• Adequate hydration 1
• Warm facial packs 1
• Sleep with head elevated 1

Oral decongestants (pseudoephedrine) or topical decongestants (oxymetazoline) may provide symptomatic relief 2:

• Limit topical decongestants to ≤5 days to avoid rebound congestion (rhinitis medicamentosa) 2

Short-term oral corticosteroids (e.g., prednisone 40-60 mg daily for 5 days) may be reasonable for 1, 2:

• Marked mucosal edema
• Failure to respond to initial antibiotic treatment
• Nasal polyposis
• Severe pain (acute hyperalgic sinusitis)

Pediatric Dosing

• Standard therapy: Amoxicillin 45 mg/kg/day divided twice daily 1
• High-dose therapy (areas with resistant S. pneumoniae or risk factors): Amoxicillin 80-90 mg/kg/day divided twice daily 1, 2
• High-dose amoxicillin-clavulanate: 80-90 mg/kg/day of amoxicillin component with 6.4 mg/kg/day clavulanate divided twice daily 1, 2
• Duration: 10-14 days 1
• Reassess at 72 hours if no improvement 1

Watchful Waiting Option

For uncomplicated acute bacterial sinusitis in adults with reliable follow-up, watchful waiting without immediate antibiotics is appropriate 1:

• Start antibiotics if no improvement by 7 days or worsening at any time 1
• Number needed to treat with antibiotics is 3-5 for persistent symptoms 1

Critical Pitfalls to Avoid

• Do not use azithromycin as first-line therapy—resistance rates are 20-25% 1
• Do not use fluoroquinolones routinely—reserve for treatment failures, severe disease, or complicated sinusitis to prevent resistance 1, 2
• Do not use topical decongestants >5 days—causes rebound congestion 2
• Complete the full antibiotic course even after symptom improvement to prevent relapse and resistance 1, 4
• Reassess at 3-5 days if no improvement—early recognition of treatment failure prevents complications 1, 2
• Take amoxicillin-clavulanate with food to reduce gastrointestinal upset 4

When to Refer to Specialist

Refer to otolaryngology or allergy/immunology for 1, 3:

• Sinusitis refractory to appropriate antibiotic treatment
• Recurrent sinusitis (≥3 episodes per year)
• Suspected complications (orbital cellulitis, meningitis, abscess)
• Need to clarify allergic or immunologic basis
• Consideration for endoscopic sinus surgery