Antibiotic Treatment for Acute Bacterial Sinusitis
Amoxicillin or amoxicillin-clavulanate are the first-line antibiotics for acute bacterial sinusitis, with treatment duration of 5-10 days. 1, 2
First-Line Antibiotic Selection
For uncomplicated acute bacterial sinusitis without recent antibiotic exposure:
- Amoxicillin 500 mg twice daily for mild disease 2
- Amoxicillin 875 mg twice daily for moderate disease 2
- High-dose amoxicillin 80-90 mg/kg/day (up to 2g per dose) in areas with high prevalence of resistant S. pneumoniae 1
For patients with risk factors (recent antibiotic use, daycare attendance, age <2 years, or severe disease):
- Amoxicillin-clavulanate 875 mg/125 mg twice daily for adults 2, 3
- High-dose amoxicillin-clavulanate 80-90 mg/kg/day of amoxicillin component with 6.4 mg/kg/day clavulanate in 2 divided doses for children 1, 2
The clavulanate component provides coverage against β-lactamase-producing H. influenzae and M. catarrhalis, which have become increasingly prevalent 1, 4.
Treatment Duration
Standard duration is 5-10 days, with most guidelines recommending treatment until symptom-free for 7 days (typically 10-14 days total) 1, 2, 5. Shorter 5-7 day courses demonstrate comparable efficacy with fewer adverse effects 5.
Penicillin-Allergic Patients
For documented penicillin allergy:
- Second-generation cephalosporins: cefuroxime-axetil 1, 2
- Third-generation cephalosporins: cefpodoxime-proxetil, cefdinir, or cefprozil 1, 2
Recent evidence demonstrates the risk of serious allergic reactions to second- and third-generation cephalosporins in penicillin-allergic patients is negligible 1, 2.
Azithromycin should NOT be used due to 20-25% resistance rates among S. pneumoniae and H. influenzae 2, 6, 4.
Second-Line Treatment for Treatment Failure
If no improvement within 72 hours (pediatrics) or 3-5 days (adults):
- Respiratory fluoroquinolones: levofloxacin 500-750 mg once daily or moxifloxacin 1, 2, 7
- High-dose amoxicillin-clavulanate if not used initially 2
Fluoroquinolones provide 90-92% predicted clinical efficacy and excellent coverage against multi-drug resistant S. pneumoniae (MDRSP) 1, 7. However, they should be reserved for treatment failures or complicated sinusitis to prevent resistance development 2, 6.
Treatment Based on Anatomic Location
For maxillary sinusitis (most common):
- Standard first-line antibiotics (amoxicillin or amoxicillin-clavulanate) 2
For frontal, ethmoidal, or sphenoidal sinusitis:
- Consider fluoroquinolones (levofloxacin or moxifloxacin) due to potential for serious complications 1, 2
Pediatric-Specific Dosing
Standard therapy:
High-dose therapy (areas with resistant S. pneumoniae or risk factors):
- Amoxicillin 80-90 mg/kg/day in 2 divided doses 1, 2
- Amoxicillin-clavulanate 80-90 mg/kg/day of amoxicillin component with 6.4 mg/kg/day clavulanate in 2 divided doses 1, 2
For children unable to tolerate oral medication:
- Ceftriaxone 50 mg/kg as single intramuscular or intravenous dose, then switch to oral therapy if improved at 24 hours 1
Adjunctive Therapies
Intranasal corticosteroids are recommended as adjuncts to antibiotic therapy in both acute and chronic sinusitis 2.
Short-term oral corticosteroids (e.g., dexamethasone 4 mg) may be considered for acute hyperalgic sinusitis (severe pain) or marked mucosal edema when combined with appropriate antibiotic therapy 2.
Critical Pitfalls to Avoid
Do not use azithromycin or other macrolides as first-line therapy due to high resistance rates (20-25%) among common pathogens 1, 2, 6.
Do not use doxycycline as first-line therapy—it has only 77-81% predicted clinical efficacy compared to 90-92% for amoxicillin-clavulanate 6.
Reassess at 72 hours (pediatrics) or 3-5 days (adults) if no improvement to avoid treatment failure 1, 2. Number needed to treat with antibiotics is 3-5 for persistent symptoms 1.
Complete the full antibiotic course even after symptoms improve to prevent relapse 2.
Reserve fluoroquinolones for second-line therapy, treatment failures, or complicated sinusitis to minimize resistance development 2, 6.