Best Antibiotic for Sinus Infections
Amoxicillin-clavulanate (Augmentin) 875 mg/125 mg twice daily for 7-10 days is the best first-line antibiotic for acute bacterial sinusitis in adults. 1
First-Line Treatment
Amoxicillin-clavulanate is the preferred initial choice because of increasing prevalence of beta-lactamase-producing organisms like H. influenzae and M. catarrhalis, which plain amoxicillin cannot adequately cover. 1, 2
The standard dosing is 875 mg/125 mg twice daily, which is as effective as the three-times-daily 500 mg/125 mg formulation but with better compliance and similar safety profile. 3
Treatment duration should be 7-10 days, with some guidelines recommending continuation until symptom-free for 7 days. 1, 2
Plain amoxicillin (500-875 mg twice daily) remains acceptable only for uncomplicated cases in patients without recent antibiotic exposure, but this is becoming less common in practice given resistance patterns. 1
Alternative First-Line Options for Penicillin Allergy
Second or third-generation cephalosporins are appropriate alternatives, including cefuroxime-axetil, cefpodoxime-proxetil (which can be effective in 5 days), or cefdinir. 4, 5, 2
For severe penicillin allergies where cephalosporins are contraindicated, macrolides (clarithromycin or azithromycin) may be used, though resistance is a concern. 6
Location-Based Treatment Considerations
The anatomic site of infection critically determines both antibiotic selection and urgency:
Maxillary sinusitis (most common): Standard first-line therapy with amoxicillin-clavulanate is appropriate. 1
Frontal, ethmoidal, or sphenoidal sinusitis: These carry higher complication risk and warrant immediate use of respiratory fluoroquinolones (levofloxacin 500-750 mg daily or moxifloxacin 400 mg daily) rather than waiting for first-line failure. 4, 1
Acute ethmoiditis in young children and sphenoidal sinus infections require urgent parenteral antibiotic therapy in hospital settings due to serious prognosis. 4
Second-Line Treatment for Failure
If no improvement occurs within 3-5 days of starting amoxicillin-clavulanate, switch to respiratory fluoroquinolones. 1, 2
Levofloxacin 750 mg daily for 5 days or 500 mg daily for 10 days, or moxifloxacin 400 mg daily for 10 days are the recommended fluoroquinolones. 1, 5
These fluoroquinolones should be reserved for treatment failure or complicated sinusitis because they have adequate activity against S. pneumoniae (the most common pathogen), unlike ciprofloxacin which has inadequate pneumococcal coverage. 5
Critical Pitfalls to Avoid
Never use ciprofloxacin for sinusitis—it has an AUC-to-MIC ratio of only 10-20 against S. pneumoniae when the target should be 25-30, making it ineffective for this indication. 5
Avoid empiric fluoroquinolone use for uncomplicated sinusitis to prevent resistance development; reserve them specifically for treatment failure or complicated disease. 5
Do not use aminopenicillins alone, first-generation cephalosporins, or cotrimoxazole due to high resistance rates. 4
Adjunctive Therapies
Intranasal corticosteroids should be used as an adjunct to antibiotic therapy to reduce inflammation and facilitate drainage. 1
Short-term oral corticosteroids are beneficial for acute hyperalgic sinusitis (severe pain) or marked mucosal edema. 4, 1
Decongestants can be used short-term (topical for no more than 3 days to avoid rhinitis medicamentosa) to facilitate drainage. 2