What is the treatment for acute sinusitis?

Treatment of Acute Sinusitis

Amoxicillin 500 mg twice daily for 10-14 days is the first-line treatment for uncomplicated acute bacterial sinusitis in adults, with high-dose amoxicillin-clavulanate (875 mg/125 mg twice daily) preferred when β-lactamase-producing organisms are suspected or in patients with recent antibiotic exposure. 1, 2

Confirming the Diagnosis Before Treatment

Before initiating antibiotics, confirm acute bacterial sinusitis by identifying one of three clinical patterns 1, 3:

• Persistent symptoms: Nasal discharge, congestion, or cough lasting ≥10 days without improvement 1, 4
• Severe onset: High fever (≥39°C) with purulent nasal discharge and facial pain for ≥3-4 consecutive days 1, 4
• "Double sickening": Worsening symptoms after initial improvement from a viral upper respiratory infection 1, 4

Physical examination should document purulent nasal discharge, sinus tenderness on palpation, and nasal congestion 3. Most acute rhinosinusitis (98-99.5%) is viral and resolves spontaneously within 7 days without antibiotics 1.

First-Line Antibiotic Selection

Standard Therapy for Uncomplicated Cases

• Amoxicillin 500 mg twice daily for mild disease without recent antibiotic exposure 1, 2
• Amoxicillin 875 mg twice daily for moderate disease or areas with high prevalence of resistant Streptococcus pneumoniae 1, 2
• Treatment duration: 10-14 days, or until symptom-free for 7 days 5, 1, 2

The predominant bacterial pathogens are Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis 5, 3. β-lactamase production occurs in up to 20% of H. influenzae strains and 50-70% of M. catarrhalis strains 5, 3.

When to Use Amoxicillin-Clavulanate First-Line

High-dose amoxicillin-clavulanate (875 mg/125 mg twice daily) should be used as first-line therapy when 1, 2:

• Recent antibiotic exposure within past 4-6 weeks
• High local resistance to amoxicillin
• Severe symptoms requiring broader coverage
• Risk factors: age <2 years, daycare attendance

Treatment for Penicillin-Allergic Patients

Non-Anaphylactic Penicillin Allergy (Rash, Mild Reactions)

Second- or third-generation cephalosporins are safe and appropriate 1, 3, 2:

• Cefuroxime-axetil (second-generation cephalosporin) 1, 2
• Cefpodoxime-proxetil (third-generation, superior activity against H. influenzae) 1, 2
• Cefdinir (third-generation, excellent coverage) 1, 2

The risk of cross-reactivity between penicillins and second/third-generation cephalosporins is negligible 1.

Severe Beta-Lactam Allergy (Anaphylaxis)

• Levofloxacin 500 mg once daily for 10-14 days 1
• Doxycycline 100 mg once daily for 10 days (acceptable alternative but suboptimal due to 20-25% predicted bacteriologic failure rate) 1

Critical caveat: Azithromycin and other macrolides should NOT be used due to 20-25% resistance rates among S. pneumoniae and H. influenzae 1, 2.

Treatment Failure Protocol

When to Reassess

• Pediatric patients: Reassess at 72 hours if no improvement 1, 3, 2
• Adult patients: Reassess at 3-5 days if no improvement 1, 3, 2

Second-Line Options After Treatment Failure

Switch to high-dose amoxicillin-clavulanate (4 g amoxicillin/250 mg clavulanate per day) if initial amoxicillin fails 1. This provides enhanced coverage against drug-resistant S. pneumoniae and β-lactamase-producing organisms 1.

For patients who fail amoxicillin-clavulanate, switch to a respiratory fluoroquinolone 1:

• Levofloxacin 500-750 mg once daily for 10 days (90-92% predicted clinical efficacy) 1, 6
• Moxifloxacin 400 mg once daily for 10 days 1

Fluoroquinolones provide excellent coverage against multi-drug resistant S. pneumoniae (MDRSP) and β-lactamase-producing H. influenzae 1, 6.

Alternative Second-Line Options

Third-generation cephalosporins offer superior activity against H. influenzae 1:

• Cefpodoxime-proxetil 1
• Cefdinir 1

Special Anatomic Considerations

Maxillary Sinusitis (Most Common)

Standard first-line antibiotics as outlined above 1. Symptoms include unilateral or bilateral infraorbital pain worsening when bending forward, pulsatile quality, peaking evening/night 1.

Frontal, Ethmoidal, or Sphenoidal Sinusitis

Reserve fluoroquinolones (levofloxacin 500-750 mg once daily or moxifloxacin 400 mg once daily) for these locations due to potential for serious complications 1, 3. These infections may require longer treatment courses of up to 28 days 3.

Adjunctive Therapies

Intranasal Corticosteroids (Strongly Recommended)

Intranasal corticosteroids should be used as adjunct to antibiotic therapy in both acute and chronic sinusitis 1, 2. Options include mometasone, fluticasone, or budesonide twice daily 1. These reduce mucosal inflammation and improve symptom resolution with strong evidence from multiple randomized controlled trials 1.

Oral Corticosteroids (Limited Role)

Short-term oral corticosteroids (typically 5 days) may be reasonable for 1, 2:

• Patients who fail initial antibiotic treatment
• Marked mucosal edema
• Nasal polyposis

Symptomatic Relief

• Analgesics: Acetaminophen or NSAIDs for pain relief 1, 2
• Decongestants: Pseudoephedrine (systemic) or topical decongestants for symptomatic relief 1, 2
• Saline nasal irrigation: For symptomatic relief 1, 2
• Supportive measures: Adequate hydration, warm facial packs, sleeping with head elevated 1

Pediatric Dosing Considerations

• Standard-dose amoxicillin: 45 mg/kg/day in 2 divided doses for uncomplicated disease 1, 3, 2
• High-dose amoxicillin: 80-90 mg/kg/day in 2 divided doses for areas with resistant S. pneumoniae or risk factors (age <2 years, daycare, recent antibiotics) 1, 3, 2
• High-dose amoxicillin-clavulanate: 80-90 mg/kg/day of amoxicillin component with 6.4 mg/kg/day clavulanate in 2 divided doses 1, 3, 2

Watchful Waiting Option

For adults with uncomplicated acute bacterial sinusitis, watchful waiting without antibiotics is an appropriate initial strategy when reliable follow-up can be assured 1, 3. Start antibiotics if no improvement by 7 days or worsening at any time 1.

Critical Pitfalls to Avoid

• Do NOT use mucus color alone to determine antibiotic need—color reflects neutrophils, not bacteria 1
• Do NOT prescribe antibiotics for viral rhinosinusitis—wait at least 10 days unless severe symptoms present 1
• Complete the full antibiotic course even after symptoms improve to prevent relapse 1, 2
• Avoid fluoroquinolone overuse—reserve for treatment failures, severe disease, or complicated sinusitis to prevent resistance development 1, 2
• Do NOT use clindamycin as monotherapy—it lacks activity against H. influenzae and M. catarrhalis 1
• Avoid cefixime and ceftibuten—poor activity against penicillin-resistant S. pneumoniae 3

When to Refer to Specialist

Refer to otolaryngology when 1, 2:

• Symptoms refractory to two courses of appropriate antibiotics
• Recurrent sinusitis (≥3 episodes per year)
• Suspected complications (orbital cellulitis, meningitis)
• Need for sinus aspiration/culture in immunocompromised patients
• Need to clarify allergic or immunologic basis for sinusitis