What is the best antibiotic for treating sinus infections?

Best Antibiotic for Sinus Infection

Amoxicillin-clavulanate (875 mg/125 mg twice daily) is the best first-line antibiotic for acute bacterial sinusitis in adults, given for 7-10 days. 1, 2

First-Line Treatment Algorithm

For uncomplicated maxillary sinusitis (most common type):

• Amoxicillin-clavulanate 875 mg/125 mg twice daily is the preferred choice due to increasing prevalence of beta-lactamase-producing organisms like H. influenzae and M. catarrhalis 2
• Plain amoxicillin 500 mg twice daily (or 875 mg twice daily for more severe infections) remains acceptable only in patients without recent antibiotic exposure 1
• Duration: 7-10 days until symptom-free for 7 days 3, 1, 2

For penicillin-allergic patients:

• Second-generation cephalosporins: cefuroxime-axetil 3
• Third-generation cephalosporins: cefpodoxime-proxetil or cefdinir 3, 1, 2
• Pristinamycin for true beta-lactam allergy 3
• Avoid azithromycin and other macrolides due to significant resistance patterns in S. pneumoniae and H. influenzae 1, 4

Treatment Based on Anatomic Location

The site of infection determines both antibiotic selection and urgency of treatment 2:

Maxillary sinusitis (most common):

• Standard first-line antibiotics as above 3, 2
• Symptoms: unilateral/bilateral infraorbital pain worsening when bending forward, pulsatile, peaking evening/night 3

Frontal, ethmoidal, or sphenoidal sinusitis (higher complication risk):

• Reserve fluoroquinolones (levofloxacin 500-750 mg daily or moxifloxacin 400 mg daily) for these locations due to potential for serious complications 3, 1, 2
• Symptoms requiring fluoroquinolones: supraorbital headache (frontal), retro-orbital pain with palpebral edema (ethmoidal), permanent retro-orbital headache radiating to vertex (sphenoidal) 3

Treatment Failure Protocol

If no improvement after 3-5 days:

• Switch to high-dose amoxicillin-clavulanate if not already prescribed 1, 2
• Consider respiratory fluoroquinolones: levofloxacin 750 mg daily for 5 days or 500 mg daily for 10 days; moxifloxacin 400 mg daily for 10 days 1, 2
• Do not use fluoroquinolones as routine first-line therapy to prevent resistance development 1

Critical Pitfalls to Avoid

Macrolide resistance: Azithromycin and clarithromycin should NOT be used for acute bacterial sinusitis due to widespread resistance, even in penicillin-allergic patients 1, 4. Despite FDA approval of clarithromycin for acute maxillary sinusitis 4, surveillance data demonstrates significant resistance making it unsuitable 1.

Fluoroquinolone overuse: Levofloxacin demonstrates 90-92% predicted clinical efficacy and 100% microbiologic eradication of S. pneumoniae 1, but should be reserved as second-line therapy to prevent resistance 1, 5. Use fluoroquinolones only for: complicated sinusitis (frontal/ethmoidal/sphenoidal), first-line treatment failure, or multi-drug resistant S. pneumoniae 3, 1.

Inadequate treatment duration: Some cephalosporins (cefuroxime-axetil, cefpodoxime-proxetil) are effective in 5-day courses 3, but standard therapy is 7-10 days 3, 1, 2. Complete the full course even after symptom improvement to prevent relapse 1.

Adjunctive Therapies

Intranasal corticosteroids are recommended as adjuncts to antibiotic therapy in both acute and chronic sinusitis 1, 2.

Short-term oral corticosteroids may be beneficial for acute hyperalgic sinusitis (severe pain) or marked mucosal edema 3, 1, 2.

Pediatric Considerations

For children:

• Amoxicillin-clavulanate 80 mg/kg/day of amoxicillin component with 6.4 mg/kg/day clavulanate in 2 divided doses 3, 1
• High-dose amoxicillin 80-90 mg/kg/day in 2 divided doses for areas with high prevalence of resistant S. pneumoniae 1
• Cefpodoxime-proxetil 8 mg/kg/day in 2 doses for penicillin-allergic children 3, 1
• Avoid macrolides, first-generation cephalosporins, and cotrimoxazole due to resistance 3