Treatment Guidelines for Acute Sinusitis
Distinguishing Bacterial from Viral Sinusitis Before Starting Antibiotics
Most acute rhinosinusitis (98-99.5%) is viral and resolves spontaneously within 7-10 days without antibiotics—antibiotics should only be prescribed when bacterial infection is confirmed by one of three specific clinical patterns. 1
Diagnose acute bacterial sinusitis (ABRS) only when the patient meets one of these three criteria: 1, 2
- Persistent symptoms ≥10 days without improvement (nasal discharge, congestion, facial pain/pressure, or cough)
- Severe symptoms for ≥3 consecutive days (fever ≥39°C [102.2°F] with purulent nasal discharge and facial pain)
- "Double sickening" (worsening of symptoms after initial improvement from a viral upper respiratory infection)
If symptoms last <10 days without severe features, treat symptomatically and withhold antibiotics. 1, 3
First-Line Antibiotic Treatment
For Adults Without Recent Antibiotic Exposure
Amoxicillin-clavulanate 875 mg/125 mg twice daily for 5-10 days is the preferred first-line antibiotic for uncomplicated acute bacterial sinusitis. 1, 4, 2
- Provides coverage against β-lactamase-producing Haemophilus influenzae and Moraxella catarrhalis 4, 2
- Plain amoxicillin 500 mg twice daily (mild disease) or 875 mg twice daily (moderate disease) is acceptable for uncomplicated cases without recent antibiotic exposure 4, 2
High-Dose Regimen for High-Risk Patients
Use high-dose amoxicillin-clavulanate (2 g amoxicillin/125 mg clavulanate twice daily) for patients with: 4, 2
- Recent antibiotic use within the past month
- Age >65 years
- Moderate-to-severe symptoms
- Comorbid conditions or immunocompromised state
- Geographic areas with high prevalence of drug-resistant Streptococcus pneumoniae
Treatment Duration
- Adults: 5-10 days, with most guidelines recommending treatment until symptom-free for 7 days (typically 10-14 days total) 1, 4, 2
- Children: 10-14 days 1, 4
- Shorter 5-7 day courses have comparable efficacy with fewer side effects for uncomplicated cases 1, 4
Pediatric Dosing
For children, amoxicillin 45 mg/kg/day in 2 divided doses is standard therapy. 4, 2
Use high-dose amoxicillin 80-90 mg/kg/day in 2 divided doses for children with: 4, 2
- Age <2 years
- Daycare attendance
- Recent antibiotic use within 4-6 weeks
- Geographic areas with high prevalence of resistant S. pneumoniae
For children with risk factors, use amoxicillin-clavulanate 80-90 mg/kg/day of amoxicillin component with 6.4 mg/kg/day clavulanate in 2 divided doses (maximum 2 g every 12 hours). 4, 2
Penicillin-Allergic Patients
Non-Severe Penicillin Allergy (Rash, Delayed Reactions)
Second- or third-generation cephalosporins are safe and preferred for patients with non-severe penicillin allergy. 1, 4, 2
Options include:
- Cefuroxime-axetil (second-generation cephalosporin) 4, 2
- Cefpodoxime-proxetil (third-generation, superior activity against H. influenzae) 4, 2
- Cefdinir (third-generation, excellent coverage) 4, 2
- Cefprozil (second-generation alternative) 2
The risk of cross-reactivity between penicillins and second/third-generation cephalosporins is negligible. 4
Severe Penicillin Allergy (Anaphylaxis/Type I Hypersensitivity)
For documented severe penicillin allergy, use respiratory fluoroquinolones: levofloxacin 500 mg once daily or moxifloxacin 400 mg once daily for 10 days. 4, 5, 6
- Provides 90-92% predicted clinical efficacy against drug-resistant S. pneumoniae and β-lactamase-producing organisms 4, 5
- Doxycycline 100 mg once daily for 10 days is an acceptable alternative but has a 20-25% predicted bacteriologic failure rate 4
Do NOT use azithromycin or other macrolides due to resistance rates exceeding 20-25% for both S. pneumoniae and H. influenzae. 1, 4
Treatment Failure Protocol
When to Reassess
Reassess patients at 3-5 days after starting antibiotics. 1, 4, 2
- If no improvement or worsening at 3-5 days: switch antibiotics immediately
- If no improvement by 7 days: reconfirm diagnosis and switch to second-line therapy
- If worsening at any time: immediately evaluate for complications (orbital cellulitis, meningitis, brain abscess) 1, 4
Second-Line Antibiotic Options
For treatment failure after first-line therapy, switch to high-dose amoxicillin-clavulanate (if not already used) or a respiratory fluoroquinolone. 1, 4, 2
Options include:
- High-dose amoxicillin-clavulanate (2 g/125 mg twice daily for 10-14 days) 4, 2
- Levofloxacin 500 mg once daily for 10-14 days 4, 5
- Moxifloxacin 400 mg once daily for 10 days 4, 6
- Third-generation cephalosporins (cefpodoxime or cefdinir) offer superior activity against H. influenzae 4
For children unable to tolerate oral medications, ceftriaxone 50 mg/kg IM as a single dose can be used. 4
Adjunctive Therapies (Strongly Recommended)
Intranasal Corticosteroids
Intranasal corticosteroids (mometasone, fluticasone, or budesonide twice daily) are strongly recommended as adjunct to antibiotic therapy in both acute and chronic sinusitis. 1, 4, 2
- Reduce mucosal inflammation and improve symptom resolution 1, 4
- Strong evidence from multiple randomized controlled trials 4
- Minimal systemic absorption 2
Saline Nasal Irrigation
Saline nasal irrigation with physiologic or hypertonic saline is recommended for symptomatic relief. 1, 4, 2
Analgesics and Decongestants
- Analgesics (acetaminophen, NSAIDs) for pain and fever relief 1, 4, 2
- Decongestants (systemic or topical) may provide symptomatic relief, though evidence for efficacy is limited 1, 2
- Topical decongestants (oxymetazoline) should be limited to 5 days to avoid rhinitis medicamentosa 1
Short-Term Oral Corticosteroids
Oral corticosteroids may be considered for patients with marked mucosal edema or who fail to respond to initial treatment, typically for 5 days. 4, 2
- Never give systemic corticosteroids without antibiotics when bacterial sinusitis is suspected, as this may suppress immune response and allow bacterial proliferation 4
What NOT to Use
Antihistamines and decongestants are NOT recommended as adjunctive treatment in acute bacterial sinusitis. 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. 4, 2
- Start antibiotics only if no improvement by 7 days or worsening at any time 4
- Approximately 73% of bacterial sinusitis cases improve spontaneously by 7-12 days without antibiotics 4
- Number needed to treat with antibiotics is 10-15 to get one additional person better after 7-15 days 4
When to Refer to a Specialist
Refer to an otolaryngologist, infectious disease specialist, or allergist when: 1, 2
- No improvement after two courses of appropriate antibiotics
- Recurrent sinusitis (≥3 episodes per year)
- Suspected complications (orbital cellulitis, meningitis, brain abscess)
- Seriously ill or immunocompromised patients
- Need for sinus aspiration/culture
- Evaluation for underlying allergic rhinitis, immunodeficiency, or anatomic abnormalities 2
Critical Pitfalls to Avoid
- Do NOT prescribe antibiotics for symptoms lasting <10 days unless severe symptoms are present (fever ≥39°C with purulent discharge for ≥3 consecutive days) 1, 4
- Do NOT use first-generation cephalosporins (cephalexin, cefadroxil) due to inadequate coverage against H. influenzae 4
- Do NOT use azithromycin or macrolides as first-line therapy due to 20-25% resistance rates 1, 4
- Do NOT use trimethoprim-sulfamethoxazole due to 50% resistance rate for S. pneumoniae 4
- Do NOT use clindamycin as monotherapy due to lack of activity against H. influenzae and M. catarrhalis 4
- Reserve fluoroquinolones for second-line therapy or severe penicillin allergy to prevent resistance development 1, 4
- Reassess at 3-5 days—waiting beyond 7 days to change therapy in non-responders delays effective treatment 4
- Complete the full antibiotic course even after symptoms improve to prevent relapse 4, 2