What are the recommended antibiotics for acute bacterial sinusitis?

Recommended Antibiotics for Acute Bacterial Sinusitis

Amoxicillin-clavulanate is the preferred first-line antibiotic for acute bacterial sinusitis in adults, dosed at 875 mg/125 mg twice daily for 5-10 days. 1

First-Line Antibiotic Selection

The choice between amoxicillin alone versus amoxicillin-clavulanate depends on recent antibiotic exposure and disease severity:

Standard First-Line Options

• Amoxicillin-clavulanate 875 mg/125 mg twice daily is recommended as the primary choice due to increasing prevalence of beta-lactamase-producing organisms (H. influenzae and M. catarrhalis) 1, 2
• Plain amoxicillin 500 mg twice daily (for mild disease) or 875 mg twice daily (for moderate disease) remains acceptable for uncomplicated cases without recent antibiotic exposure 1, 2
• The 2015 American Academy of Otolaryngology guideline allows either amoxicillin with or without clavulanate as first-line therapy 1

Treatment Duration

• 5-10 days is the recommended duration, with most guidelines suggesting treatment until symptom-free for 7 days 1, 2
• Shorter 5-7 day courses have comparable efficacy with fewer side effects 1
• The traditional 10-14 day duration is still acceptable but may not provide additional benefit 2

Penicillin-Allergic Patients

For patients with documented penicillin allergy (non-Type I hypersensitivity):

• Second-generation cephalosporins: cefuroxime-axetil 1, 2
• Third-generation cephalosporins: cefpodoxime-proxetil or cefdinir 1, 2
• Recent evidence shows the risk of serious allergic reactions to second- and third-generation cephalosporins in penicillin-allergic patients is negligible 1

Critical caveat: Azithromycin and other macrolides should NOT be used for acute bacterial sinusitis due to significant resistance patterns (20-25% bacterial failure rate), even in penicillin-allergic patients 1, 2

Second-Line Treatment for Failure

If no improvement occurs within 72 hours (pediatrics) 1 or 7 days (adults) 1:

Reassessment Required

• Confirm the diagnosis of acute bacterial sinusitis 1
• Exclude complications or alternative diagnoses 1
• Consider imaging if not previously obtained 1

Second-Line Antibiotic Options

• High-dose amoxicillin-clavulanate (if not already used) 2, 3
• Respiratory fluoroquinolones: levofloxacin 500-750 mg daily or moxifloxacin 400 mg daily for 5-10 days 1, 2, 4
• Fluoroquinolones demonstrate 90-92% clinical efficacy and 100% microbiologic eradication for S. pneumoniae, including multi-drug resistant strains 2, 4

Important limitation: Reserve fluoroquinolones for treatment failures, complicated sinusitis (frontal, ethmoidal, or sphenoidal involvement), or multi-drug resistant pathogens to prevent resistance development 2, 5

Treatment Based on Anatomic Location

Maxillary Sinusitis (Most Common)

• Use standard first-line antibiotics (amoxicillin-clavulanate or amoxicillin) 2, 5
• Presents with infraorbital pain worsening when bending forward, pulsatile quality, peaking evening/night 2

Frontal, Ethmoidal, or Sphenoidal Sinusitis

• Fluoroquinolones (levofloxacin or moxifloxacin) are preferred due to higher risk of serious complications 2, 5
• These locations warrant more aggressive initial therapy 2

Pediatric Dosing (Ages 1-18 Years)

Standard Therapy

• Amoxicillin 45 mg/kg/day in 2 divided doses for mild disease without recent antibiotic use 1, 2
• High-dose amoxicillin 80-90 mg/kg/day in 2 divided doses for areas with high prevalence of resistant S. pneumoniae, age <2 years, daycare attendance, or recent antibiotic use 1, 2

Alternative for Penicillin Allergy

• Amoxicillin-clavulanate 90 mg/kg/day of amoxicillin component with 6.4 mg/kg/day clavulanate in 2 divided doses 1, 2
• Cefpodoxime proxetil 8 mg/kg/day in two doses 2
• Ceftriaxone 50 mg/kg as single dose for children unable to tolerate oral medication 2

Adjunctive Therapies

• Intranasal corticosteroids are recommended as adjunct to antibiotic therapy in both acute and chronic sinusitis 2, 3, 5
• Short-term oral corticosteroids (e.g., dexamethasone 4 mg) may be considered for acute hyperalgic sinusitis (severe pain) or marked mucosal edema 2, 3
• Supportive measures include adequate hydration, analgesics, warm facial packs, and sleeping with head elevated 2

Watchful Waiting Option

For adults with uncomplicated acute bacterial sinusitis:

• Watchful waiting without antibiotics is an appropriate initial strategy when follow-up can be assured 1
• Start antibiotics if no improvement by 7 days or worsening at any time 1
• This approach reduces adverse events and antibiotic resistance while maintaining comparable outcomes given favorable natural history (51% spontaneous improvement within 3 days on placebo) 1

Critical Pitfalls to Avoid

• Do not use azithromycin or other macrolides as first-line therapy due to 20-25% resistance rates 1, 2
• Do not routinely prescribe fluoroquinolones as initial therapy; reserve for treatment failures or complicated cases 2, 5
• Ensure adequate treatment duration (minimum 5 days, typically 7-10 days) to prevent relapse 1, 2
• Reassess at 3 days (pediatrics) or 7 days (adults) if no improvement to avoid treatment failure 1
• Recent research shows high-dose amoxicillin-clavulanate (1750 mg amoxicillin twice daily) does NOT provide additional benefit over standard dosing (875 mg twice daily) and may increase diarrhea risk 6, 7