What is the recommended treatment for a patient with acute sinusitis?

Treatment for Acute Sinusitis

Confirm Bacterial Infection Before Prescribing Antibiotics

Most acute sinusitis (98-99.5%) is viral and resolves spontaneously within 7-10 days without antibiotics—only prescribe antibiotics when bacterial infection is confirmed by one of three criteria: persistent symptoms ≥10 days without improvement, severe symptoms (fever ≥39°C with purulent discharge) for ≥3-4 consecutive days, or "double sickening" (worsening after initial improvement) 1, 2.

• Wait at least 10 days before considering antibiotics unless severe symptoms are present 1, 2.
• Watchful waiting without immediate antibiotics is an appropriate initial strategy when reliable follow-up can be assured, with antibiotics started only if no improvement by 7 days or symptoms worsen at any time 1, 2.

First-Line Antibiotic Treatment

Amoxicillin-clavulanate 875 mg/125 mg twice daily for 5-10 days is the preferred first-line antibiotic for confirmed acute bacterial sinusitis in adults, providing superior coverage against β-lactamase-producing organisms (Haemophilus influenzae and Moraxella catarrhalis) with 90-92% predicted clinical efficacy 1, 2.

• Use high-dose amoxicillin-clavulanate (2 g/125 mg twice daily) for patients with recent antibiotic use within the past month, age >65 years, moderate-to-severe symptoms, comorbid conditions, or immunocompromised state 1, 2.
• Plain amoxicillin 500 mg twice daily (mild disease) or 875 mg twice daily (moderate disease) remains acceptable for uncomplicated cases without recent antibiotic exposure 1, 2.
• Treatment duration is 5-10 days, with most guidelines recommending treatment until symptom-free for 7 days (typically 10-14 days total) 1, 2.

Penicillin-Allergic Patients

For documented penicillin allergy (non-anaphylactic), prescribe second- or third-generation cephalosporins: cefuroxime-axetil, cefpodoxime-proxetil, or cefdinir for 10 days, as the risk of cross-reactivity is negligible 1, 2.

• For severe penicillin allergy (anaphylaxis), prescribe levofloxacin 500 mg once daily for 10-14 days as first-line therapy 1, 3.
• Never use azithromycin or other macrolides as first-line therapy due to resistance rates exceeding 20-25% for both S. pneumoniae and H. influenzae 1, 2, 4.
• Avoid trimethoprim-sulfamethoxazole due to 50% resistance rates for S. pneumoniae 1, 3.

Essential Adjunctive Therapies

Prescribe intranasal corticosteroids (mometasone, fluticasone, or budesonide) twice daily for all patients with acute bacterial sinusitis to reduce mucosal inflammation and improve drainage, with a number needed to treat of 14 1, 2.

• Recommend saline nasal irrigation to promote mucus clearance and reduce tissue edema 1, 3.
• Prescribe analgesics (acetaminophen or NSAIDs) for pain management based on severity 1, 3.
• Consider short-term oral corticosteroids (5 days) for marked mucosal edema or failure to respond to initial antibiotic therapy 1, 2.

Treatment Failure Protocol

Reassess at 3-5 days: if no improvement, switch to a respiratory fluoroquinolone (levofloxacin 500-750 mg once daily or moxifloxacin 400 mg once daily) for 10-14 days 1, 3, 5.

• At 7 days: confirm the diagnosis of acute bacterial sinusitis if symptoms persist or worsen 1, 3.
• Respiratory fluoroquinolones provide 90-92% predicted clinical efficacy and excellent coverage against multi-drug resistant S. pneumoniae 1, 3, 5.

When to Refer to a Specialist

Refer to otolaryngology or infectious disease if: no improvement after 7 days of appropriate second-line therapy, worsening symptoms at any time, suspected complications (orbital cellulitis, meningitis, abscess formation), recurrent sinusitis (≥3 episodes per year), or need for sinus aspiration/culture in immunocompromised patients 1, 3.

Pediatric Dosing

For children, prescribe amoxicillin 45 mg/kg/day in 2 divided doses for standard therapy, or high-dose amoxicillin 80-90 mg/kg/day in 2 divided doses for high-risk children (age <2 years, daycare attendance, recent antibiotic use) 1, 2.

• Switch to high-dose amoxicillin-clavulanate (80-90 mg/kg/day of amoxicillin component with 6.4 mg/kg/day clavulanate in 2 divided doses) for treatment failure at 72 hours 1, 2.
• Pediatric patients require 10-14 days of treatment 1, 2.

Critical Pitfalls to Avoid

• Never prescribe antibiotics for symptoms lasting <10 days unless severe symptoms are present (fever ≥39°C with purulent discharge for ≥3 consecutive days) 1, 2.
• Never use first-generation cephalosporins (cephalexin) due to inadequate H. influenzae coverage 3, 2.
• Never use fluoroquinolones as routine first-line therapy in patients without documented β-lactam allergies to prevent resistance development 1, 3.
• Ensure adequate treatment duration (minimum 5 days, typically 7-10 days) to prevent relapse 1, 2.