What is the recommended treatment for acute sinusitis in a healthy adult patient with no significant underlying health conditions?

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—do not prescribe antibiotics unless the patient meets specific bacterial criteria. 1, 2

Diagnose acute bacterial rhinosinusitis (ABRS) only when one of three patterns is present: 1, 2, 3

• Persistent symptoms ≥10 days without improvement (nasal congestion, purulent discharge, facial pain/pressure)
• Severe symptoms ≥3-4 consecutive days (fever ≥39°C with purulent nasal discharge)
• "Double sickening": worsening after initial improvement from a viral upper respiratory infection

First-Line Antibiotic Treatment

For adults with confirmed ABRS, prescribe amoxicillin-clavulanate 875 mg/125 mg twice daily for 5-10 days as first-line therapy. 1, 2, 3, 4

The combination provides superior coverage against β-lactamase-producing Haemophilus influenzae and Moraxella catarrhalis, which have become increasingly prevalent and render plain amoxicillin less effective. 2, 3 Predicted clinical efficacy is 90-92% against major pathogens (Streptococcus pneumoniae, H. influenzae, M. catarrhalis). 2

Alternative: Watchful waiting without immediate antibiotics is equally appropriate for uncomplicated ABRS when reliable follow-up can be assured—start antibiotics only if no improvement by 7 days or symptoms worsen at any time. 1, 2, 3

High-Dose Amoxicillin-Clavulanate for High-Risk Patients

Use amoxicillin-clavulanate 2 g/125 mg twice daily for patients with: 2, 3

• Recent antibiotic use within past 4-6 weeks
• Age >65 years
• Moderate-to-severe symptoms
• Comorbid conditions or immunocompromised state

Recent evidence shows conflicting results on high-dose efficacy: one trial found 18% greater improvement at day 3 with immediate-release high-dose formulation 5, while another larger trial found no benefit and stopped early for futility. 6 Given this equipoise, reserve high-dose for the specific risk factors above rather than routine use.

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, 3 Recent evidence supports shorter 5-7 day courses with comparable efficacy and fewer adverse effects. 2, 7

Penicillin-Allergic Patients

Non-Severe Penicillin Allergy (Rash, Mild Reactions)

Use second- or third-generation cephalosporins as first-line alternatives—the risk of cross-reactivity is negligible: 1, 2, 3

• Cefuroxime-axetil (second-generation)
• Cefpodoxime-proxetil (third-generation, superior H. influenzae activity)
• Cefdinir (third-generation)

Dose cefdinir 300 mg twice daily or 600 mg once daily for 10 days. 2

Severe Penicillin Allergy (Anaphylaxis/Type I Hypersensitivity)

Use respiratory fluoroquinolones: 1, 2, 3

• Levofloxacin 500 mg once daily for 10-14 days (preferred)
• Moxifloxacin 400 mg once daily for 10 days

These provide 90-92% predicted clinical efficacy with excellent coverage against drug-resistant S. pneumoniae and β-lactamase-producing organisms. 2

Alternative: Doxycycline 100 mg once daily for 10 days is acceptable but suboptimal, with only 77-81% predicted efficacy and limited H. influenzae activity. 2

What NOT to Use

Never use these as first-line therapy due to high resistance rates: 1, 2, 3

• Azithromycin and macrolides: 20-25% resistance for S. pneumoniae and H. influenzae
• Trimethoprim-sulfamethoxazole: 50% resistance for S. pneumoniae, 27% for H. influenzae
• First-generation cephalosporins (cephalexin): inadequate H. influenzae coverage

Reassessment and Treatment Failure Protocol

Reassess at 3-5 days: If no improvement or worsening, switch antibiotics immediately. 1, 2, 3

Reassess at 7 days: If symptoms persist, reconfirm diagnosis and switch to second-line therapy: 1, 2

• High-dose amoxicillin-clavulanate (if not already used)
• Respiratory fluoroquinolone (levofloxacin or moxifloxacin)
• Third-generation cephalosporin (cefpodoxime or cefdinir)

Refer to ENT specialist if: 1, 2, 3

• No improvement after 7 days of appropriate second-line therapy
• Symptoms refractory to two courses of antibiotics
• Suspected complications (orbital cellulitis, meningitis, brain abscess)
• Recurrent sinusitis (≥3 episodes per year)

Essential Adjunctive Therapies

Add these to antibiotic therapy in ALL patients to improve outcomes: 1, 2, 3

• Intranasal corticosteroids (mometasone, fluticasone, or budesonide twice daily): Reduce mucosal inflammation and improve symptom resolution with strong RCT evidence
• Saline nasal irrigation: Provides symptomatic relief and removes mucus
• Analgesics (acetaminophen or ibuprofen): For pain and fever
• Adequate hydration

Short-term oral corticosteroids may be considered for patients with marked mucosal edema or who fail initial treatment, typically for 5 days. 1, 2

Pediatric Dosing

Standard-dose amoxicillin: 45 mg/kg/day in 2 divided doses for 10-14 days 2, 3, 4

High-dose amoxicillin: 80-90 mg/kg/day in 2 divided doses for: 2, 3

• Age <2 years
• Daycare attendance
• Recent antibiotic use within 4-6 weeks
• Areas with high prevalence of resistant S. pneumoniae

High-dose amoxicillin-clavulanate: 80-90 mg/kg/day of amoxicillin component with 6.4 mg/kg/day clavulanate in 2 divided doses for treatment failures or children with risk factors. 2, 3

Reassess pediatric patients at 72 hours—switch to high-dose amoxicillin-clavulanate if no improvement. 2

Critical Pitfalls to Avoid

Do not prescribe antibiotics for symptoms <10 days unless severe features present (fever ≥39°C with purulent discharge for ≥3 consecutive days)—this promotes antimicrobial resistance without benefit. 1, 2, 3

Do not use fluoroquinolones as first-line therapy in patients without documented β-lactam allergies—reserve them to prevent resistance development. 1, 2

Do not use mucus color alone to determine antibiotic need—purulent discharge reflects neutrophils, not necessarily bacteria. 2

Ensure adequate treatment duration (minimum 5 days, typically 7-10 days)—inadequate duration leads to relapse. 1, 2

Do not wait beyond 7 days to change therapy in non-responders—this delays effective treatment and may allow complications. 2

Expected Timeline for Improvement

Most patients should experience noticeable improvement within 3-5 days of starting appropriate antibiotic therapy. 2 By 7 days, approximately 73-85% show clinical improvement. 2 Complete resolution typically occurs by 10-14 days or when symptom-free for 7 consecutive days. 1, 2

If worsening at any time, immediately reassess for complications and switch antibiotics. 1, 2