What is the recommended management for acute sinusitis in a generally healthy adult without penicillin allergy, including indications for antibiotics and the first‑line antibiotic regimen?

Management of Acute Sinusitis in Generally Healthy Adults Without Penicillin Allergy

Distinguishing Bacterial from Viral Sinusitis

Most acute rhinosinusitis (98-99.5%) is viral and resolves spontaneously within 7-10 days without antibiotics. 1, 2 You should diagnose acute bacterial rhinosinusitis (ABRS) only when the patient meets one of three specific clinical patterns:

• Persistent symptoms ≥10 days without improvement: purulent nasal discharge accompanied by nasal obstruction, facial pain/pressure/fullness, or both 1, 2
• Severe symptoms for ≥3-4 consecutive days: fever ≥39°C (102°F) with purulent nasal discharge and facial pain 1, 2, 3
• "Double worsening": initial improvement from a viral URI followed by worsening symptoms within 10 days 1, 2

Do not obtain imaging (X-ray or CT) for uncomplicated acute rhinosinusitis unless you suspect complications or an alternative diagnosis. 1, 2 Radiographic abnormalities appear in approximately 87% of viral URIs and cannot differentiate bacterial from viral disease. 2

Initial Management Strategy: Watchful Waiting vs. Immediate Antibiotics

For uncomplicated ABRS, you may offer either watchful waiting without antibiotics OR prescribe immediate antibiotic therapy. 1 Watchful waiting is appropriate only when you can ensure reliable follow-up, with antibiotics started if the patient fails to improve by 7 days or worsens at any time. 1, 2

The number needed to treat with antibiotics is 10-15 to achieve one additional cure over 7-15 days, reflecting the high spontaneous recovery rate. 2 However, approximately 73-85% of patients improve by 7 days even with placebo treatment. 2

First-Line Antibiotic Therapy

If you decide to prescribe antibiotics, amoxicillin-clavulanate 875 mg/125 mg twice daily for 5-10 days is the preferred first-line agent for most adults. 1, 2, 4 This regimen provides 90-92% predicted clinical efficacy against the three major pathogens: Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis. 2, 4

The preference for amoxicillin-clavulanate over plain amoxicillin reflects the increasing prevalence of β-lactamase-producing organisms—approximately 30-40% of H. influenzae and 90-100% of M. catarrhalis strains produce β-lactamase. 2, 5

When to Use High-Dose Amoxicillin-Clavulanate

Prescribe high-dose amoxicillin-clavulanate (2 g/125 mg twice daily) for patients with:

• Recent antibiotic use within the past 4-6 weeks 2
• Age >65 years 2
• Moderate-to-severe symptoms 2
• Comorbid conditions or immunocompromised state 2

Treatment Duration

Continue antibiotics for 5-10 days, or until the patient is symptom-free for 7 consecutive days (typically 10-14 days total). 1, 2 Recent evidence supports shorter 5-7 day courses with comparable efficacy and fewer adverse effects. 2

Essential Adjunctive Therapies for All Patients

Add intranasal corticosteroids (mometasone, fluticasone, or budesonide) twice daily to all patients regardless of whether you prescribe antibiotics. 1, 2, 6 Multiple randomized controlled trials demonstrate that intranasal corticosteroids significantly reduce mucosal inflammation and accelerate symptom resolution. 2, 6

Recommend saline nasal irrigation 2-3 times daily to provide symptomatic relief and clear mucus. 1, 2, 6

Prescribe analgesics (acetaminophen or ibuprofen) for pain and fever control. 1, 2, 6

Decongestants may provide short-term relief but limit topical agents to ≤3 days to avoid rebound congestion (rhinitis medicamentosa). 6

Monitoring and Reassessment Protocol

Reassess at 3-5 days after starting antibiotics:

• If no improvement, switch immediately to high-dose amoxicillin-clavulanate (if not already prescribed) or a respiratory fluoroquinolone (levofloxacin 500 mg once daily or moxifloxacin 400 mg once daily for 10 days) 1, 2, 4
• If symptoms worsen at any time, evaluate urgently for complications (orbital cellulitis, meningitis, brain abscess) 1, 2

Reassess at 7 days:

• If symptoms persist or worsen, reconfirm the diagnosis of ABRS using the three clinical patterns above 1, 2
• Exclude complications and consider alternative diagnoses 1, 2
• Reserve CT imaging for suspected complications only 1, 2

Most patients with bacterial sinusitis show noticeable improvement within 3-5 days, with complete resolution by 10-14 days. 2, 4 Only 30-41% improve by days 3-5, so lack of complete resolution at this early timepoint does not necessarily indicate treatment failure. 2

Antibiotics to Avoid

Never use azithromycin or other macrolides as first-line therapy due to resistance rates exceeding 20-25% for both S. pneumoniae and H. influenzae. 2, 4

Avoid trimethoprim-sulfamethoxazole due to 50% resistance in S. pneumoniae and 27% resistance in H. influenzae. 2

Do not use first-generation cephalosporins (cephalexin, cefadroxil) because they provide inadequate coverage against H. influenzae—approximately 50% of strains produce β-lactamase. 2

Common Pitfalls to Avoid

Do not prescribe antibiotics for symptoms lasting <10 days unless severe features are present (fever ≥39°C with purulent discharge for ≥3 consecutive days). 1, 2, 3 This practice contributes to antimicrobial resistance without clinical benefit, as 98-99.5% of cases are viral. 2

Do not use mucus color alone to determine antibiotic need—color reflects neutrophils, not bacteria. 2

Ensure adequate treatment duration (minimum 5 days for adults) to prevent relapse. 2

Do not delay switching antibiotics in non-responders beyond 3-5 days, as this allows complications to develop. 2

When to Refer to Otolaryngology

Refer patients when:

• No improvement after 7 days of appropriate second-line antibiotic therapy 2
• Worsening symptoms at any point during treatment 2
• Suspected complications (severe headache, visual changes, periorbital swelling, altered mental status) 2, 3
• Recurrent sinusitis (≥3 episodes per year) requiring evaluation for underlying allergic rhinitis, immunodeficiency, or anatomic abnormalities 1, 2, 6