What is the appropriate treatment for a patient with a sinus infection, considering their medical history, potential allergies, and symptom severity?

Treatment of Sinus Infection

For acute bacterial sinusitis, amoxicillin-clavulanate 875 mg/125 mg twice daily for 5-10 days is the preferred first-line antibiotic for most adults, but watchful waiting without immediate antibiotics is equally appropriate when reliable follow-up can be assured. 1

Confirm the Diagnosis Before Prescribing Antibiotics

Before starting any antibiotic, verify the patient meets one of three diagnostic criteria for bacterial sinusitis (not viral rhinosinusitis, which accounts for 98-99.5% of cases): 1

• Persistent symptoms ≥10 days without clinical improvement (nasal congestion, purulent discharge, facial pain/pressure) 1
• Severe symptoms for ≥3-4 consecutive days: fever ≥39°C with purulent nasal discharge 1
• "Double sickening": worsening symptoms after initial improvement from a viral upper respiratory infection 1

Do not prescribe antibiotics for symptoms lasting less than 10 days unless severe features are present, as most cases resolve spontaneously within 7-10 days. 1

First-Line Antibiotic Treatment

Amoxicillin-clavulanate 875 mg/125 mg twice daily for 5-10 days is the preferred first-line agent, providing 90-92% predicted clinical efficacy against the major pathogens (Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis). 1, 2 The clavulanate component covers β-lactamase-producing organisms, which have become increasingly prevalent. 1

Take each dose with a meal or snack to reduce gastrointestinal upset. 2

When to Use High-Dose Amoxicillin-Clavulanate

Use high-dose amoxicillin-clavulanate (2 g amoxicillin/125 mg clavulanate twice daily) for patients with: 1

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

Alternative First-Line Option: Plain Amoxicillin

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

Treatment Duration

Standard duration is 5-10 days, with most guidelines recommending treatment until symptom-free for 7 days (typically 10-14 days total). 1 Recent evidence supports shorter 5-7 day courses with comparable efficacy and fewer adverse effects. 1

Watchful Waiting Strategy

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

Penicillin-Allergic Patients

Non-Severe Penicillin Allergy (Rash, Mild Reactions)

Second- or third-generation cephalosporins are safe and preferred: 1

• Cefuroxime-axetil (second-generation) 1
• Cefpodoxime-proxetil, cefdinir, or cefprozil (third-generation) 1

The risk of cross-reactivity with penicillin allergy is negligible for these agents. 1

Severe Penicillin Allergy (Anaphylaxis/Type I Hypersensitivity)

Respiratory fluoroquinolones are the treatment of choice: 1

• Levofloxacin 500 mg once daily for 10-14 days 1
• Moxifloxacin 400 mg once daily for 10 days 1

These provide 90-92% predicted clinical efficacy with excellent coverage against drug-resistant S. pneumoniae and β-lactamase-producing organisms. 1

Doxycycline 100 mg once daily for 10 days is an acceptable alternative but has a predicted bacteriologic failure rate of 20-25% and limited activity against H. influenzae. 1

What NOT to Use

Avoid these antibiotics due to high resistance rates: 1

• Azithromycin and other macrolides: 20-25% resistance for both S. pneumoniae and H. influenzae 1
• Trimethoprim-sulfamethoxazole: 50% resistance for S. pneumoniae, 27% for H. influenzae 1
• First-generation cephalosporins (cephalexin): inadequate coverage against H. influenzae 1

Essential Adjunctive Therapies

All patients should receive symptomatic treatment regardless of antibiotic choice: 1

• Intranasal corticosteroids (mometasone, fluticasone, or budesonide twice daily): reduce mucosal inflammation and improve symptom resolution 1
• Saline nasal irrigation: provides symptomatic relief and removes mucus 1
• Analgesics (acetaminophen or ibuprofen): for pain and fever 1
• Adequate hydration 3
• Warm facial packs, sleeping with head elevated 3

When to Reassess and Switch Antibiotics

Critical reassessment timepoints: 1

Day 3-5

If no improvement or worsening symptoms, switch to second-line therapy immediately: 1

• High-dose amoxicillin-clavulanate (if not already used) 1
• Respiratory fluoroquinolone (levofloxacin or moxifloxacin) 1
• Third-generation cephalosporin (cefpodoxime or cefdinir) 1

Day 7

If symptoms persist or worsen: 1

• Reconfirm the diagnosis using clinical criteria
• Consider imaging (CT) only if complications suspected
• Switch to broader-spectrum antibiotics if bacterial sinusitis confirmed

Expected Timeline for Improvement

Most patients should experience noticeable improvement within 3-5 days of starting appropriate antibiotic therapy. 1 Complete resolution typically occurs by 10-14 days or when symptom-free for 7 consecutive days. 1

By day 3-5: reduction in fever, facial pain, and purulent nasal discharge 1 By day 7: approximately 73-85% show clinical improvement 1 By 7-15 days: 86-91% achieve cure or improvement with appropriate antibiotics 1

When to Refer to a Specialist

Refer to otolaryngology or allergist-immunologist for: 4, 3

• No improvement after 7 days of appropriate second-line antibiotic therapy
• Worsening symptoms at any time
• Suspected complications (orbital cellulitis, meningitis, brain abscess)
• Recurrent sinusitis (≥3 episodes per year)
• Chronic sinusitis (symptoms >8 weeks)
• Need to evaluate for underlying allergic rhinitis, immunodeficiency, or anatomic abnormalities

Critical Pitfalls to Avoid

• Do not prescribe antibiotics for viral rhinosinusitis lasting <10 days unless severe symptoms are present 1
• Do not use fluoroquinolones as first-line therapy in patients without documented β-lactam allergies—this promotes antimicrobial resistance 1
• Do not wait beyond 7 days to change therapy in non-responders—this delays effective treatment 1
• Do not use azithromycin or macrolides as first-line therapy due to 20-25% resistance rates 1
• Ensure adequate treatment duration (minimum 5 days, typically 7-10 days) to prevent relapse 1

Special Considerations for Chronic Sinusitis

Chronic sinusitis (symptoms ≥8 weeks) requires fundamentally different management: 5

• Daily high-volume saline irrigation combined with intranasal corticosteroid sprays as first-line treatment 5
• Evaluate for underlying allergic rhinitis, GERD, and asthma 5
• Reserve antibiotics for chronic infectious sinusitis with evidence of active bacterial infection, potentially requiring longer duration therapy (up to 3 months) 5
• Refer to otolaryngologist when first-line medical therapy fails after 8-12 weeks 5