Treatment for Sinus Infection
For acute bacterial sinusitis, amoxicillin 500 mg twice daily for 10-14 days is the first-line treatment, but antibiotics should only be started when symptoms persist beyond 10 days or worsen after 5-7 days of initial improvement. 1
When to Start Antibiotics
The most critical decision is distinguishing viral from bacterial sinusitis, as most sinus infections are viral and self-limited:
- Wait 10 days before starting antibiotics if symptoms are persistent but not worsening, as bacterial sinusitis is uncommon before this timeframe 2
- Start antibiotics earlier (after 5-7 days) if symptoms initially improve then worsen 2
- Start antibiotics immediately for severe presentations with high fever and purulent discharge for 3-4 consecutive days 3
- Provide symptomatic treatment (analgesics, decongestants, saline irrigation) during the observation period 1
This watchful waiting approach reduces unnecessary antibiotic use while accepting that some bacterial infections may be treated later than ideal—a reasonable trade-off given the public health impact of antibiotic resistance 2
First-Line Antibiotic Treatment
Standard Therapy
- Amoxicillin 500 mg twice daily for uncomplicated cases 1
- Amoxicillin 875 mg twice daily for more severe infections 1
- Duration: 10-14 days until symptom-free for 7 days 1
For Penicillin Allergy
- Cephalosporins (cefuroxime-axetil, cefpodoxime-proxetil, cefdinir) are appropriate alternatives 1, 2
- Pristinamycin for true beta-lactam allergy 2
- Do NOT use azithromycin due to high resistance rates in Streptococcus pneumoniae and Haemophilus influenzae 1
Critical pitfall: Azithromycin is explicitly not recommended despite being commonly prescribed, as surveillance studies demonstrate significant resistance patterns that make it unsuitable for sinusitis treatment 1
Second-Line Treatment (Treatment Failure)
If no improvement after 3-5 days of initial therapy:
- Switch to amoxicillin-clavulanate for better coverage against beta-lactamase-producing organisms 1, 4
- Consider fluoroquinolones (levofloxacin or moxifloxacin) for complicated cases involving frontal, ethmoidal, or sphenoidal sinuses 2, 1
- Reserve fluoroquinolones for treatment failures or high-risk situations, not routine first-line use 2
Site-Specific Considerations
Maxillary Sinusitis (Most Common)
- Standard first-line antibiotics as above 2
- Presents with unilateral or bilateral infraorbital pain worsening when bending forward 2
Frontal, Ethmoidal, or Sphenoidal Sinusitis
- Higher risk of complications requiring more aggressive treatment 2
- Consider fluoroquinolones (levofloxacin, moxifloxacin) as first-line for these sites 2, 1
- May require hospitalization if complications suspected 2
Adjunctive Therapies
- Intranasal corticosteroids are recommended as adjuncts to antibiotics in both acute and chronic sinusitis 1
- Short-term oral corticosteroids (e.g., dexamethasone 4 mg) may be used for acute hyperalgic sinusitis (severe pain) or marked mucosal edema 1
- Saline irrigation facilitates mucus removal 5
- Adequate hydration, analgesics, warm facial packs for symptom relief 1
Important caveat: Systemic corticosteroids like dexamethasone should never be used as monotherapy—antibiotics remain essential for bacterial infection 1
Pediatric Dosing
- Amoxicillin 45 mg/kg/day in 2 divided doses for standard therapy 1
- High-dose amoxicillin 80-90 mg/kg/day in areas with resistant S. pneumoniae or for children <2 years, in daycare, or with recent antibiotic use 1
- Azithromycin 10 mg/kg once daily for 3 days is FDA-approved but should be avoided due to resistance concerns 6, 1
Red Flags Requiring Specialist Referral
- Meningeal signs, exophthalmos, palpebral edema, ocular mobility disorders 2
- Severe pain preventing sleep 2
- Recurrent sinusitis (≥3 episodes per year) 1
- Failure to respond to appropriate antibiotic therapy 1
- Immunocompromised patients 4
Key Microbiology
The primary pathogens are: