What is the recommended treatment plan for acute bacterial sinusitis, including first‑line antibiotic choice, alternatives for penicillin allergy, adjunct intranasal corticosteroid spray, saline nasal irrigation, analgesic use, dosing instructions, and follow‑up?

Treatment Plan for Acute Bacterial Sinusitis

For adults with acute bacterial sinusitis, prescribe amoxicillin-clavulanate 875 mg/125 mg twice daily for 5–10 days as first-line therapy, combined with intranasal corticosteroid spray (mometasone or fluticasone, 2 sprays per nostril twice daily), saline nasal irrigation (high-volume, hypertonic 3–5% solution), and analgesics (acetaminophen or NSAIDs) for symptom relief. 1, 2, 3

Confirming the Diagnosis

Before initiating antibiotics, confirm acute bacterial rhinosinusitis (ABRS) using one of three clinical patterns: 4, 1, 3

• Persistent symptoms: Purulent nasal drainage plus nasal obstruction or facial pain-pressure-fullness lasting ≥10 days without improvement 4
• Severe symptoms: High fever (≥102°F) with purulent nasal discharge for ≥3–4 consecutive days 3, 5
• Double worsening: Initial improvement followed by worsening of respiratory symptoms within 10 days 4, 1

Do not obtain imaging (CT or plain radiographs) for uncomplicated cases, as it does not change management and viral infections show similar abnormalities. 4, 3

First-Line Antibiotic Therapy

Standard-dose amoxicillin-clavulanate 875 mg/125 mg twice daily is the preferred first-line antibiotic for most adults with uncomplicated ABRS. 1, 3, 5

High-dose amoxicillin-clavulanate (2000 mg/125 mg twice daily) should be used in patients with: 1

• Recent antibiotic use within the past month
• Age >65 years
• Moderate-to-severe symptoms
• Comorbid conditions (diabetes, COPD, heart disease)
• Immunocompromised state
• Geographic areas with high prevalence of penicillin-resistant S. pneumoniae

Treatment duration: 5–10 days for adults (5–7 days is sufficient for uncomplicated cases). 1, 3

Penicillin Allergy Alternatives

For non-severe penicillin allergy (rash without anaphylaxis), use second- or third-generation cephalosporins: 1, 3

• Cefuroxime-axetil, cefpodoxime-proxetil, cefdinir, or cefprozil
• Same 5–10 day duration

For severe penicillin allergy (anaphylaxis, angioedema, severe urticaria), use respiratory fluoroquinolones: 1, 3

• Levofloxacin 500 mg once daily for 5–7 days, OR
• Moxifloxacin 400 mg once daily for 5–7 days

Avoid macrolides (azithromycin, clarithromycin) due to high rates of S. pneumoniae resistance (>30% in most regions). 6

Mandatory Adjunctive Therapies

These should be prescribed to all patients regardless of antibiotic choice: 1, 2

Intranasal Corticosteroid Spray

• Preferred agents: Mometasone furoate or fluticasone propionate (negligible systemic absorption) 2
• Dosing: 2 sprays per nostril twice daily (total 200–400 µg/day) 2
• Duration: Continue for 15–21 days (concurrent with antibiotic course) 2
• Mechanism: Reduces mucosal inflammation, nasal congestion, and purulent drainage 2
• Evidence: Increases treatment success from 66% to 73% (NNT = 14); in recurrent cases, success improves from 74% to 93% 2
• Patient instruction: Direct spray away from nasal septum to minimize bleeding risk 2
• Onset: Patients may not perceive improvement for 3–5 days; counsel against premature discontinuation 2

Saline Nasal Irrigation

• Type: High-volume (≥150 mL per nostril), hypertonic (3–5%) saline solution 2
• Frequency: 2–3 times daily 4, 1
• Mechanism: Mechanical clearance of purulent secretions and inflammatory mediators 2

Analgesics

• Options: Acetaminophen or NSAIDs (ibuprofen, naproxen) 4, 1
• Purpose: Facial pain-pressure-fullness relief 4
• Dosing: Standard over-the-counter dosing as needed

Therapies to Avoid

Do not prescribe: 3

• Oral or topical decongestants (no proven benefit; rebound congestion with prolonged use)
• Antihistamines (unless concurrent allergic rhinitis; may thicken secretions)
• Topical or systemic antifungal agents (no benefit demonstrated) 2

Watchful Waiting Option

For adults with uncomplicated ABRS and mild symptoms, watchful waiting without immediate antibiotics is acceptable only when reliable follow-up is assured. 4, 1, 3

• Prescribe intranasal corticosteroids, saline irrigation, and analgesics for symptomatic relief 4, 1
• Start antibiotics if no improvement by 7 days or worsening at any time 4, 1
• Evidence: Without antibiotics, 46% cure at 1 week and 64% at 14 days; antibiotics add only 5–11 more cures per 100 patients (NNT 10–19) but cause side effects in 13 more per 100 (NNTH 8) 7

Follow-Up and Treatment Failure

Reassess at 7 days if symptoms persist or worsen: 4, 1

• If initially managed with watchful waiting: Start amoxicillin-clavulanate 4
• If initially treated with amoxicillin-clavulanate: Switch to high-dose amoxicillin-clavulanate or respiratory fluoroquinolone 4, 1
• Exclude complications (orbital cellulitis, meningitis, brain abscess) and alternative diagnoses 4, 5

Refer to otolaryngology if: 1, 3

• No improvement after 7 days of appropriate second-line therapy
• Suspected complications (periorbital swelling, severe headache, altered mental status, visual changes)
• Recurrent episodes (≥4 per year) suggesting chronic rhinosinusitis
• Immunocompromised state

Common Pitfalls to Avoid

• Prescribing macrolides as first-line therapy: High resistance rates make azithromycin and clarithromycin inappropriate choices despite their convenience. 6
• Omitting intranasal corticosteroids: This adjunctive therapy significantly improves outcomes and should be prescribed to all patients. 2
• Using imaging routinely: CT or plain films do not distinguish bacterial from viral infection and are unnecessary in uncomplicated cases. 4, 3
• Treating viral upper respiratory infections with antibiotics: Most "sinus infections" are viral and resolve spontaneously; reserve antibiotics for patients meeting ABRS diagnostic criteria. 4, 7
• Inadequate patient counseling on intranasal steroid technique: Improper spray direction toward the septum increases bleeding risk and reduces efficacy. 2