Treatment of Acute Sinusitis
Distinguish Viral from Bacterial Sinusitis First
Most acute rhinosinusitis (98-99.5%) is viral and resolves spontaneously within 7-10 days without antibiotics. 1 You should only prescribe antibiotics when the patient meets one of three specific criteria for acute bacterial rhinosinusitis (ABRS): 1, 2
- Persistent symptoms ≥10 days without improvement 1, 2
- Severe symptoms (fever ≥39°C with purulent nasal discharge) for ≥3-4 consecutive days 1, 2
- "Double sickening": worsening after initial improvement from a viral upper respiratory infection 1, 2
Do not prescribe antibiotics for symptoms lasting less than 10 days unless severe features are present. 1
First-Line Antibiotic Treatment
For Adults Without Penicillin Allergy
Amoxicillin-clavulanate 875 mg/125 mg twice daily for 5-10 days is the preferred first-line antibiotic. 1, 2, 3 This provides 90-92% predicted clinical efficacy against the major pathogens (Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis). 1, 4 The clavulanate component is essential because 30-50% of H. influenzae and 90-100% of M. catarrhalis produce β-lactamase, rendering plain amoxicillin ineffective. 1, 4
Watchful waiting without immediate antibiotics is equally appropriate when reliable follow-up can be assured—start antibiotics only if no improvement by 7 days or symptoms worsen at any time. 1, 2
High-Dose Amoxicillin-Clavulanate for High-Risk Patients
Use amoxicillin-clavulanate 2000 mg/125 mg twice daily for patients with: 1, 2
- Recent antibiotic use within the past 4-6 weeks
- Age >65 years
- Moderate-to-severe symptoms
- Comorbid conditions or immunocompromised state
Treatment Duration
Treat for 5-10 days, with most guidelines recommending treatment until symptom-free for 7 days (typically 10-14 days total). 1, 2 Recent evidence supports shorter 5-7 day courses with comparable efficacy and fewer adverse effects. 1, 5
For Penicillin-Allergic Patients
Non-Severe Penicillin Allergy (Rash, Mild Reactions)
Second- or third-generation cephalosporins are safe and preferred: 1, 4, 2
- Cefuroxime-axetil (second-generation) 1, 4
- Cefpodoxime-proxetil (third-generation with superior H. influenzae activity) 1, 4
- Cefdinir (third-generation) 1, 4
The risk of cross-reactivity between penicillins and second/third-generation cephalosporins is negligible. 1
Severe Penicillin Allergy (Anaphylaxis/Type I Hypersensitivity)
Respiratory fluoroquinolones are the treatment of choice: 1, 4, 2
These provide 90-92% predicted clinical efficacy with excellent coverage against drug-resistant S. pneumoniae and β-lactamase-producing organisms. 1, 4
Doxycycline 100 mg once daily for 10 days is an acceptable but suboptimal alternative, with only 77-81% predicted efficacy and limited activity against H. influenzae. 1, 4
What NOT to Use
Avoid these antibiotics due to high resistance rates: 1, 4, 2
- Azithromycin and other macrolides: 20-25% resistance for both S. pneumoniae and H. influenzae 1, 4
- Trimethoprim-sulfamethoxazole (Bactrim/Septra): 50% resistance for S. pneumoniae, 27% for H. influenzae 1, 4
- First-generation cephalosporins (cephalexin): inadequate coverage against H. influenzae 1, 4
Reassessment and Treatment Failure Protocol
Critical Timepoints
- If no improvement or worsening, switch to second-line therapy immediately
- Only 30-41% of patients improve by days 3-5, so lack of complete resolution does not necessarily indicate failure 1
- If symptoms persist or worsen, reconfirm diagnosis and exclude complications
- This is the critical decision point for changing management
Second-Line Therapy After Treatment Failure
Switch to high-dose amoxicillin-clavulanate (2000 mg/125 mg twice daily) or a respiratory fluoroquinolone (levofloxacin or moxifloxacin). 1, 4, 2 These provide superior coverage against drug-resistant S. pneumoniae and β-lactamase-producing organisms. 1, 4
Essential Adjunctive Therapies
These should be offered to ALL patients regardless of antibiotic choice: 1, 2
- Intranasal corticosteroids (mometasone, fluticasone, or budesonide twice daily): reduce mucosal inflammation and improve symptom resolution 1, 2
- Saline nasal irrigation: provides symptomatic relief and removes mucus 1, 2
- Analgesics (acetaminophen or ibuprofen): relieve pain and fever 1, 2
- Adequate hydration 1, 2
Short-term oral corticosteroids may be considered for patients with marked mucosal edema or who fail to respond to initial treatment. 1, 4
Pediatric Dosing
Standard Therapy
Amoxicillin 45 mg/kg/day in 2 divided doses for 10-14 days for children ≥3 months with uncomplicated disease. 1, 2
High-Dose Therapy for High-Risk Children
Amoxicillin 80-90 mg/kg/day in 2 divided doses OR amoxicillin-clavulanate 80-90 mg/kg/day (of amoxicillin component) with 6.4 mg/kg/day clavulanate in 2 divided doses for children with: 1, 2
- Age <2 years
- Daycare attendance
- Recent antibiotic use within past 4-6 weeks
- Areas with high prevalence of resistant S. pneumoniae
Reassess pediatric patients at 72 hours—switch to high-dose amoxicillin-clavulanate if worsening or no improvement. 1, 2
When to Refer to a Specialist
Refer to otolaryngology or allergy/immunology for: 1, 2
- Symptoms refractory to 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
Critical Pitfalls to Avoid
- Do not prescribe antibiotics for viral rhinosinusitis lasting <10 days unless severe symptoms are present—this promotes antimicrobial resistance without clinical benefit 1, 2
- Do not use fluoroquinolones as first-line therapy in patients without documented β-lactam allergies—reserve them for treatment failures or severe allergies to prevent resistance development 1, 4
- Do not use plain amoxicillin when amoxicillin-clavulanate is appropriate—the increasing prevalence of β-lactamase-producing organisms makes plain amoxicillin inadequate 1, 2
- Ensure adequate treatment duration (minimum 5 days for adults, 10 days for children) to prevent relapse 1, 2
- Gastrointestinal adverse effects are common with amoxicillin-clavulanate, particularly diarrhea (reported in 40-43% of patients, with severe diarrhea in 7-8%) 5, 6