Treatment of Acute Sinusitis
For adults with acute bacterial sinusitis, amoxicillin-clavulanate 875 mg/125 mg twice daily for 5-7 days is the first-line treatment, with antibiotics initiated only when specific diagnostic criteria are met: persistent symptoms ≥10 days without improvement, severe symptoms (fever ≥39°C with purulent discharge) for ≥3 consecutive days, or "double sickening" (worsening after initial viral improvement). 1, 2
Confirm Bacterial Sinusitis Before Prescribing Antibiotics
Most acute rhinosinusitis (98-99.5%) is viral and resolves spontaneously within 7-10 days without antibiotics 1, 2. Do not prescribe antibiotics for symptoms lasting less than 10 days unless severe symptoms are present 1, 2. The three diagnostic patterns that justify antibiotic therapy are:
- Persistent symptoms: Nasal discharge, congestion, or facial pain lasting ≥10 days without improvement 1, 2
- Severe symptoms: Fever ≥39°C with purulent nasal discharge for ≥3 consecutive days 1, 2
- Double sickening: Worsening symptoms after initial improvement from a viral upper respiratory infection 1, 2
Watchful waiting without immediate antibiotics is appropriate when reliable follow-up can be assured, with antibiotics started only if no improvement occurs by 7 days or symptoms worsen at any time 2.
First-Line Antibiotic Treatment
Adults
Amoxicillin-clavulanate 875 mg/125 mg twice daily for 5-7 days is the preferred first-line agent 1, 2. The IDSA guideline explicitly recommends amoxicillin-clavulanate over plain amoxicillin for adults (weak recommendation, low-quality evidence) 1. The clavulanate component provides essential coverage against β-lactamase-producing Haemophilus influenzae and Moraxella catarrhalis, which have become increasingly prevalent 2.
High-dose amoxicillin-clavulanate (2 g amoxicillin/125 mg clavulanate twice daily) should be used for patients with: 1, 2
- Recent antibiotic use within the past month
- Age >65 years
- Moderate-to-severe symptoms
- Comorbid conditions (diabetes, heart disease, COPD)
- Immunocompromised state
Plain amoxicillin 500 mg twice daily (mild disease) or 875 mg twice daily (moderate disease) remains acceptable only for uncomplicated cases without recent antibiotic exposure 2.
Children
Amoxicillin-clavulanate rather than amoxicillin alone is recommended as empiric therapy for children (strong recommendation, moderate-quality evidence) 1. High-dose amoxicillin-clavulanate (80-90 mg/kg/day of amoxicillin component with 6.4 mg/kg/day clavulanate in 2 divided doses) should be used for children with risk factors 1, 2:
- Age <2 years
- Daycare attendance
- Recent antibiotic use within 4-6 weeks
- High local prevalence of resistant S. pneumoniae
Standard-dose amoxicillin (45 mg/kg/day in 2 divided doses) may be used for uncomplicated cases without these risk factors 2.
Treatment duration for children is 10-14 days (weak recommendation, low-moderate quality evidence), which is longer than the 5-7 days recommended for adults 1, 2.
Treatment Duration
- Adults: 5-7 days for uncomplicated acute bacterial sinusitis 1, 2
- Children: 10-14 days 1, 2
- Alternative approach: Treat until symptom-free for 7 days (typically 10-14 days total) 2, 3
Shorter 5-7 day courses have comparable efficacy to 10-day regimens with fewer adverse effects in adults 2, 4.
Penicillin-Allergic Patients
Non-Severe Allergy (Rash, Delayed Reactions)
Second- or third-generation cephalosporins are safe and preferred 1, 2:
- Cefuroxime-axetil (second-generation): Effective alternative with good coverage 2
- Cefpodoxime-proxetil (third-generation): Superior activity against H. influenzae 2
- Cefdinir (third-generation): Excellent coverage, well-tolerated 2
The risk of cross-reactivity between penicillins and second/third-generation cephalosporins is negligible for non-Type I reactions 2.
Severe Allergy (Anaphylaxis/Type I Hypersensitivity)
Respiratory fluoroquinolones are first-line when β-lactams are contraindicated 1, 2:
These provide 90-92% predicted clinical efficacy against drug-resistant S. pneumoniae and β-lactamase-producing H. influenzae 2.
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 2.
What NOT to Use in Penicillin-Allergic Patients
Azithromycin and other macrolides should NOT be used due to resistance rates exceeding 20-25% for both S. pneumoniae and H. influenzae 1, 2, 5. The American Academy of Pediatrics explicitly states that azithromycin should not be used to treat acute bacterial sinusitis in persons with penicillin hypersensitivity due to resistance patterns 2.
Trimethoprim-sulfamethoxazole should NOT be used due to 50% resistance rates for S. pneumoniae and 27% for H. influenzae 2.
Treatment Failure Protocol
When to Reassess
Reassess at 3-5 days: If no improvement or worsening occurs, switch antibiotics or re-evaluate the diagnosis 1, 2. For children, reassess at 72 hours 1, 2.
Reassess at 7 days: Confirm the diagnosis of acute bacterial sinusitis if symptoms persist or worsen 2.
Second-Line Options After First-Line Failure
If amoxicillin-clavulanate fails after 3-5 days, switch to: 1, 2
Respiratory fluoroquinolones (preferred):
High-dose amoxicillin-clavulanate (if not already used): 2 g amoxicillin/125 mg clavulanate twice daily 2
Third-generation cephalosporins:
Ceftriaxone 1-2 g IM or IV once daily for 5 days for patients who cannot tolerate oral medications or have moderate-to-severe disease with recent antibiotic exposure 2. For children, use 50 mg/kg IM or IV once daily 2.
Essential Adjunctive Therapies
These should be prescribed for ALL patients with acute bacterial sinusitis, regardless of antibiotic choice:
Intranasal Corticosteroids (Strongly Recommended)
Prescribe mometasone, fluticasone, or budesonide twice daily 1, 2. These reduce mucosal inflammation, improve drainage, and enhance symptom resolution with strong evidence from multiple randomized controlled trials 2. The IDSA recommends intranasal corticosteroids as an adjunct to antibiotics, primarily in patients with a history of allergic rhinitis (weak recommendation, moderate-quality evidence) 1.
Saline Nasal Irrigation
Recommend intranasal saline irrigation with physiologic or hypertonic saline 1, 2. This promotes mucus clearance, reduces tissue edema, and provides symptomatic relief (weak recommendation, low-moderate quality evidence) 1.
Analgesics
Prescribe acetaminophen or NSAIDs for pain management 2. These relieve facial pain, pressure, and fever 2.
Short-Term Oral Corticosteroids (Selected Cases)
Consider oral corticosteroids for 5 days in patients with: 1, 2
- Marked mucosal edema
- Failure to respond to initial antibiotic treatment
- Nasal polyposis
These should never be given without antibiotics when bacterial sinusitis is suspected, as this may suppress the immune response and allow bacterial proliferation 2.
What NOT to Use
Decongestants and antihistamines are NOT recommended as adjunctive treatment in patients with acute bacterial sinusitis (strong recommendation, low-moderate quality evidence) 1. These have limited evidence for efficacy and may cause adverse effects 2.
When to Refer to a Specialist
Refer to otolaryngology when: 1, 2
- No improvement after 7 days of appropriate second-line therapy
- Worsening symptoms at any time despite treatment
- Suspected complications (orbital cellulitis, meningitis, brain abscess)
- Recurrent sinusitis (≥3 episodes per year)
- Seriously ill or immunocompromised patients
- Need for sinus aspiration/culture
Critical Pitfalls to Avoid
Do not prescribe antibiotics for viral rhinosinusitis lasting <10 days unless severe symptoms are present 1, 2. This contributes to antimicrobial resistance without clinical benefit.
Do not use fluoroquinolones as routine first-line therapy in patients without documented β-lactam allergies 2. Reserve these for treatment failures or severe penicillin allergy to prevent resistance development.
Do not use first-generation cephalosporins (cephalexin) due to inadequate coverage against H. influenzae 2. Nearly 50% of H. influenzae strains are β-lactamase producing, rendering cephalexin ineffective.
Do not use clindamycin as monotherapy due to lack of activity against H. influenzae and M. catarrhalis 2. If used, it must be combined with a third-generation cephalosporin.
Do not continue ineffective therapy beyond 3-5 days (adults) or 72 hours (children) 1, 2. Early reassessment is designed to catch treatment failures before complications develop.
Ensure adequate treatment duration to prevent relapse 2. Minimum 5 days for adults, 10-14 days for children.