Treatment of Acute Bacterial Sinusitis
Amoxicillin-clavulanate 875 mg/125 mg twice daily for 5-10 days is the recommended first-line treatment for adults with acute bacterial sinusitis. 1
Confirming the Diagnosis Before Starting Antibiotics
Before prescribing antibiotics, confirm the patient meets one of three diagnostic criteria for acute bacterial sinusitis 1:
- Persistent symptoms ≥10 days without improvement (nasal discharge, congestion, facial pain/pressure)
- 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
Most acute rhinosinusitis (98-99.5%) is viral and resolves spontaneously within 7-10 days without antibiotics. 1 Do not prescribe antibiotics for symptoms lasting less than 10 days unless severe symptoms are present. 1
First-Line Antibiotic Treatment
Adults
Amoxicillin-clavulanate 875 mg/125 mg twice daily for 5-10 days is the preferred first-line agent. 1, 2 This provides coverage against β-lactamase-producing Haemophilus influenzae and Moraxella catarrhalis, which have become increasingly prevalent. 2, 3
For patients with high-risk features (recent antibiotic use within past month, age >65 years, moderate-to-severe symptoms, comorbidities, or immunocompromised state), use high-dose amoxicillin-clavulanate 2 g/125 mg twice daily. 1, 2
Treatment duration: 5-7 days for uncomplicated cases in adults, though most guidelines recommend continuing until symptom-free for 7 days (typically 10-14 days total). 1, 2
Children
High-dose amoxicillin-clavulanate 90 mg/kg/day of amoxicillin component with 6.4 mg/kg/day clavulanate in 2 divided doses is recommended for children, especially those with risk factors (age <2 years, daycare attendance, recent antibiotic use). 1, 2
Treatment duration for children: 10-14 days. 1, 2 The longer duration in children is necessary despite adult data supporting shorter courses. 1
Penicillin-Allergic Patients
Non-Severe Allergy (Rash, Delayed Reaction)
Second- or third-generation cephalosporins are safe and preferred for patients with non-Type I penicillin allergy. 1, 2 The risk of cross-reactivity is negligible. 2
Options include:
- Cefuroxime-axetil (second-generation cephalosporin) 1, 2
- Cefpodoxime-proxetil (third-generation, superior activity against H. influenzae) 1, 2
- Cefdinir (third-generation) 1, 2
Dosing: Cefdinir 300 mg twice daily or 600 mg once daily for 10 days. 2
Severe Allergy (Anaphylaxis, Type I Hypersensitivity)
Respiratory fluoroquinolones are the treatment of choice when β-lactams are contraindicated. 1, 2
These provide 90-92% predicted clinical efficacy against drug-resistant Streptococcus pneumoniae and β-lactamase-producing organisms. 1, 2
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. 2
What NOT to Use
Azithromycin and other macrolides should NOT be used for acute bacterial sinusitis due to resistance rates exceeding 20-25% for both S. pneumoniae and H. influenzae. 1, 2 The American Academy of Pediatrics explicitly contraindicates azithromycin for this indication. 2
First-generation cephalosporins (cephalexin, cefadroxil) should NOT be used due to inadequate coverage against H. influenzae, with nearly 50% of strains being β-lactamase producing. 2
Trimethoprim-sulfamethoxazole should NOT be used due to 50% resistance rates for S. pneumoniae and 27% for H. influenzae. 2
When to Reassess and Switch Antibiotics
Reassess at 3-5 days: If no improvement or worsening symptoms, switch to second-line therapy. 1, 2 For children, reassess at 72 hours. 1, 2
Reassess at 7 days: If symptoms persist, reconfirm the diagnosis and consider complications or alternative diagnoses. 1, 2
Second-Line Treatment Options
If initial therapy fails:
Switch to high-dose amoxicillin-clavulanate (if not already used) or respiratory fluoroquinolone (levofloxacin 500 mg once daily or moxifloxacin 400 mg once daily for 10 days). 1, 2
Third-generation cephalosporins (cefpodoxime, cefdinir) offer superior activity against H. influenzae but have limitations against drug-resistant S. pneumoniae. 2
Ceftriaxone 1-2 g IM or IV once daily for 5 days is indicated when patients cannot tolerate oral medications or have moderate-to-severe disease with recent antibiotic exposure. 2 For children: 50 mg/kg once daily. 2
Essential Adjunctive Therapies
These should be added to antibiotic therapy to improve outcomes:
Intranasal corticosteroids (mometasone, fluticasone, or budesonide twice daily) reduce mucosal inflammation and improve symptom resolution. 1, 2 Strong evidence from multiple randomized controlled trials supports their use. 2
Saline nasal irrigation (high-volume, physiologic or hypertonic saline) provides symptomatic relief and removes mucus. 1, 2
Analgesics (acetaminophen or NSAIDs) for pain and fever relief. 1, 2
Short-term oral corticosteroids may be considered for patients with marked mucosal edema or who fail to respond to initial treatment, typically for 5 days. 1, 2
What NOT to Use as Adjunctive Therapy
Oral or topical decongestants and antihistamines are NOT recommended as adjunctive treatment in acute bacterial sinusitis. 1 If topical decongestants are used, limit to 3-5 days maximum to avoid rebound congestion. 4
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, 2 Instruct patients to start antibiotics only if no improvement occurs by 7 days or if symptoms worsen at any time. 2
Approximately 73% of bacterial sinusitis cases show spontaneous improvement by 7-12 days without antibiotics. 2 The number needed to treat with antibiotics is 10-15 to get one additional person better after 7-15 days. 2
When to Refer to a Specialist
Refer to otolaryngology or allergist-immunologist for 1, 2:
- No improvement after 7 days of appropriate second-line antibiotic therapy
- Worsening symptoms at any time despite treatment
- Suspected complications (orbital cellulitis, meningitis, brain abscess)
- Recurrent sinusitis (≥3 episodes per year)
- Chronic sinusitis (symptoms >8 weeks)
- Need for evaluation of underlying allergic rhinitis, immunodeficiency, or anatomic abnormalities
Critical Pitfalls to Avoid
Do not prescribe antibiotics for viral rhinosinusitis lasting less than 10 days unless severe symptoms are present. 1, 2 This contributes to antimicrobial resistance without clinical benefit.
Do not use fluoroquinolones as first-line therapy in patients without documented β-lactam allergies. 1, 2 Reserve them for treatment failures or severe allergies to prevent resistance development.
Do not continue ineffective therapy beyond 3-5 days (72 hours in children) without reassessment. 1, 2 Early recognition of treatment failure is essential.
Do not use inadequate treatment duration. Complete the full course even after symptoms improve to prevent relapse. 2 For adults: minimum 5-7 days; for children: 10-14 days. 1
Do not use systemic corticosteroids without antibiotics when bacterial sinusitis is suspected, as this may suppress the immune response and allow bacterial proliferation. 2