What is the recommended treatment for a patient with a sinus infection?

Treatment of Acute Bacterial Sinusitis

For adults with acute bacterial sinusitis, start with amoxicillin-clavulanate 875 mg/125 mg twice daily for 5-10 days, as this provides superior coverage against β-lactamase-producing organisms compared to amoxicillin alone. 1

Confirming the Diagnosis Before Starting Antibiotics

Before prescribing antibiotics, confirm the patient meets one of three diagnostic criteria for bacterial (not viral) sinusitis 1:

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

Critical pitfall: 98-99.5% of acute rhinosinusitis is viral and resolves spontaneously within 7-10 days without antibiotics 1. Do not prescribe antibiotics for symptoms lasting <10 days unless severe symptoms are present 1.

First-Line Antibiotic Treatment

Standard Patients (No Recent Antibiotics, Age <65, No Comorbidities)

Amoxicillin-clavulanate 875 mg/125 mg twice daily for 5-10 days is the preferred first-line agent 1. This combination covers the three main pathogens: Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis 1. The clavulanate component is essential because 50% of H. influenzae and 90-100% of M. catarrhalis produce β-lactamase 1.

Plain amoxicillin 500-875 mg twice daily remains acceptable for uncomplicated cases without recent antibiotic exposure 1, though amoxicillin-clavulanate is generally preferred 1.

High-Risk Patients

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

Evidence note: Two recent randomized trials 2, 3 showed conflicting results on whether high-dose provides additional benefit over standard-dose, but guidelines still recommend high-dose for high-risk patients 1.

Treatment Duration

Treat for 5-10 days, or until symptom-free for 7 consecutive days (typically 10-14 days total) 1. Recent evidence supports shorter 5-7 day courses for uncomplicated cases with comparable efficacy and fewer adverse effects 1.

Penicillin-Allergic Patients

Non-Severe Allergy (Rash, Mild Reactions)

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

• Cefuroxime-axetil (second-generation)
• Cefpodoxime-proxetil (third-generation)
• Cefdinir (third-generation)

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

Severe Type I Allergy (Anaphylaxis)

Respiratory fluoroquinolones are the treatment of choice 1:

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

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

Alternative: Doxycycline 100 mg once daily for 10 days is acceptable but has a 20-25% predicted bacteriologic failure rate 1.

Critical pitfall: Never use azithromycin or other macrolides due to resistance rates exceeding 20-25% for both S. pneumoniae and H. influenzae 1, 4. The FDA label lists azithromycin 500 mg daily for 3 days for acute bacterial sinusitis 4, but current guidelines explicitly contraindicate its use due to resistance 1.

When to Reassess and Switch Antibiotics

Reassess at 3-5 days 1:

• If no improvement or worsening, switch to second-line therapy immediately
• If partial improvement, continue current antibiotic for full course

Reassess at 7 days 1:

• If symptoms persist, reconfirm diagnosis and switch to second-line therapy
• Consider complications (orbital cellulitis, meningitis) if worsening

Second-Line Options After Treatment Failure

If amoxicillin-clavulanate fails 1:

1. Respiratory fluoroquinolones (levofloxacin 500 mg daily or moxifloxacin 400 mg daily for 10 days) - provides 90-92% efficacy against resistant organisms 1

2. Third-generation cephalosporins (cefpodoxime or cefdinir) - superior activity against H. influenzae 1

3. Ceftriaxone 1-2 g IM/IV once daily for 5 days - for patients unable to tolerate oral medications or with moderate-to-severe disease 1

Essential Adjunctive Therapies

Always add these regardless of antibiotic choice 1:

• Intranasal corticosteroids (mometasone, fluticasone, or budesonide twice daily) - reduces mucosal inflammation and improves symptom resolution with strong RCT evidence 1
• Saline nasal irrigation - provides symptomatic relief and removes mucus 1
• Analgesics (acetaminophen or NSAIDs) - for pain and fever 1
• Adequate hydration 5

Short-term oral corticosteroids (typically 5 days) may be reasonable for patients with marked mucosal edema or who fail initial treatment 5, 1, though they should never be given without antibiotics when bacterial sinusitis is suspected 1.

Watchful Waiting Option

For adults with uncomplicated acute bacterial sinusitis, watchful waiting without immediate antibiotics is appropriate when reliable follow-up can be assured 1. Instruct patients to start antibiotics only if no improvement by 7 days or if symptoms worsen at any time 1. This approach is reasonable because approximately 73% of bacterial sinusitis cases improve spontaneously by 7-12 days without antibiotics 1.

When to Refer to a Specialist

Refer to otolaryngology or allergy/immunology for 5, 1:

• No improvement after two courses of appropriate antibiotics
• Recurrent sinusitis (≥3 episodes per year)
• Suspected complications (orbital cellulitis, meningitis, brain abscess)
• Need for evaluation of underlying allergic rhinitis, immunodeficiency, or anatomic abnormalities

Pediatric Considerations

For children ≥6 months with acute bacterial sinusitis 1:

• Standard-dose amoxicillin: 45 mg/kg/day in 2 divided doses
• High-dose amoxicillin: 80-90 mg/kg/day in 2 divided doses (for age <2 years, daycare attendance, recent antibiotic use, or high local resistance)
• High-dose amoxicillin-clavulanate: 90 mg/kg/day of amoxicillin component with 6.4 mg/kg/day clavulanate in 2 divided doses (for treatment failure or risk factors)
• Duration: 10-14 days (children require longer courses than adults) 1
• Reassess at 72 hours and switch to amoxicillin-clavulanate if no improvement 1

For penicillin-allergic children, use cefpodoxime proxetil 8 mg/kg/day in two doses 1.