Treatment of Sinus Infections
For acute bacterial sinusitis, start with amoxicillin 500 mg twice daily (or 875 mg twice daily for more severe infections) for 10-14 days, reserving amoxicillin-clavulanate for treatment failures or patients with recent antibiotic exposure. 1
Distinguishing Viral from Bacterial Sinusitis
Before prescribing antibiotics, confirm bacterial infection by identifying one of three patterns 1:
- Persistent symptoms ≥10 days without clinical improvement 1
- Severe symptoms (fever >39°C, purulent nasal discharge, facial pain) for ≥3 consecutive days 1
- "Double sickening" - worsening symptoms after initial improvement from a viral upper respiratory infection 1
Critical pitfall: Most acute rhinosinusitis (98-99.5%) is viral and resolves spontaneously within 7 days without antibiotics 1. Antibiotics are prescribed in 81-92% of cases despite only 0.5-2% having bacterial etiology 1.
First-Line Antibiotic Treatment
Standard Therapy
Amoxicillin remains the first-line choice 1:
- Mild disease: 500 mg twice daily for 10-14 days 1
- Moderate-severe disease: 875 mg twice daily for 10-14 days 1
- Pediatric dosing: 45 mg/kg/day in 2 divided doses (standard) or 80-90 mg/kg/day in 2 divided doses (high-dose for resistant S. pneumoniae) 1
When to Use Amoxicillin-Clavulanate Instead
Amoxicillin-clavulanate (875 mg/125 mg twice daily) is preferred for 1:
- Recent antibiotic exposure within past 4-6 weeks 1
- More severe infections 1
- Treatment failures after 3-5 days of amoxicillin 1
- Children with risk factors (age <2 years, daycare attendance) 1
Shorter 5-7 day courses have comparable efficacy with fewer side effects 1.
Penicillin-Allergic Patients
Classify the Allergy Type First
For non-anaphylactic reactions (rash, mild reactions), cephalosporins are safe and preferred 1:
- Second-generation: Cefuroxime-axetil 1
- Third-generation: Cefpodoxime-proxetil, cefdinir, or cefprozil 1
- Pediatric dosing: Cefpodoxime 8 mg/kg/day in two doses 1
The risk of cross-reactivity between penicillins and second/third-generation cephalosporins is negligible 1.
For True Anaphylactic Allergy
Reserve respiratory fluoroquinolones for documented severe beta-lactam allergy 1:
Critical pitfall: Azithromycin should NOT be used for acute bacterial sinusitis due to 20-25% resistance rates for both S. pneumoniae and H. influenzae 1, 2. French guidelines explicitly exclude macrolides from recommended therapy 1.
Second-Line Treatment for Failures
If no improvement after 3-5 days, switch antibiotics 1:
Treatment Algorithm for Failures
First failure (after amoxicillin): Switch to high-dose amoxicillin-clavulanate (90 mg/kg/day of amoxicillin component with 6.4 mg/kg/day clavulanate in 2 divided doses, maximum 2 g every 12 hours) 1
Second failure (after amoxicillin-clavulanate): Switch to respiratory fluoroquinolones 1:
Pediatric treatment failure: Clindamycin (15 mg/kg three times daily) PLUS cefixime or cefpodoxime to cover both resistant S. pneumoniae and gram-negative organisms 1
Critical pitfall: Never use clindamycin as monotherapy for sinusitis—it lacks activity against H. influenzae and M. catarrhalis, causing failure in 30-40% of cases 1.
Adjunctive Therapies (Essential for All Patients)
Intranasal Corticosteroids (Strongly Recommended)
Intranasal corticosteroids are the cornerstone of adjunctive therapy 1, 4:
- Mometasone, fluticasone, or budesonide twice daily 1
- Reduce mucosal inflammation and improve symptom resolution 1
- Continue for 3 months if cough disappears with treatment 5
- Strong evidence from multiple randomized controlled trials 1
Supportive Measures
Provide symptomatic relief with 1:
- Saline nasal irrigation: Prevents crusting and facilitates mechanical mucus removal 4
- Analgesics: Acetaminophen or NSAIDs for pain 1
- Decongestants: Pseudoephedrine or oxymetazoline (limit topical use to 5 days) 5, 1
- Adequate hydration, warm facial packs, sleeping with head elevated 1
Oral Corticosteroids (Limited Use)
Short-term oral corticosteroids (e.g., dexamethasone 4 mg) may be considered for 1:
- Acute hyperalgic sinusitis (severe pain) not responding to other treatments 1
- Marked mucosal edema 1
- Duration: Typically 5 days 1
Critical caveat: Systemic corticosteroids should never be used as monotherapy—antibiotics remain necessary for bacterial infection 1.
Special Considerations by Anatomic Location
Maxillary Sinusitis (Most Common)
Use standard first-line antibiotics 1:
- Symptoms include unilateral/bilateral infraorbital pain worsening when bending forward, pulsatile, peaking evening/night 1
Frontal, Ethmoidal, or Sphenoidal Sinusitis
Reserve fluoroquinolones due to potential for serious complications 1:
When to Refer to a Specialist
Refer to otolaryngology for 1:
- Symptoms refractory to two courses of appropriate antibiotics 1
- Recurrent sinusitis (≥3 episodes per year) 1
- Suspected complications (orbital cellulitis, meningitis) 1, 6
- Need for sinus aspiration/culture in immunocompromised patients 1
- Anatomic abnormalities requiring endoscopic sinus surgery 5
Critical Pitfalls to Avoid
Do not prescribe antibiotics for viral rhinosinusitis—wait at least 10 days unless severe symptoms are present 1. Mucus color alone does not indicate bacterial infection, as color reflects neutrophils, not bacteria 1.
Complete the full antibiotic course even after symptoms improve to prevent relapse 1. Inadequate treatment duration is a common cause of treatment failure 1.
Avoid fluoroquinolone overuse to prevent resistance development—reserve for treatment failures, severe disease, or complicated sinusitis 1. Never use as routine first-line therapy 1.
Reassess patients at 3 days (pediatrics) or 3-5 days (adults) if no improvement 1. Consider complications, alternative diagnosis, or specialist referral if symptoms worsen or fail to improve 1.