What is the first line treatment for a patient with uncomplicated bacterial sinusitis?

First-Line Treatment for Bacterial Sinusitis

Amoxicillin-clavulanate 875 mg/125 mg twice daily for 5-10 days is the preferred first-line treatment for uncomplicated acute bacterial sinusitis in adults. 1, 2

When to Prescribe Antibiotics

Before initiating antibiotics, confirm the diagnosis meets one of three bacterial criteria:

• Persistent symptoms: Nasal discharge or daytime cough lasting >10 days without improvement 3, 1
• Severe onset: Fever ≥39°C (102.2°F) with purulent nasal discharge for ≥3 consecutive days 3, 1
• Worsening course ("double sickening"): Initial improvement from viral URI followed by worsening or new onset of symptoms 3, 1

Most acute rhinosinusitis (98-99.5%) is viral and resolves spontaneously within 7-10 days without antibiotics—do not prescribe antibiotics for symptoms lasting <10 days unless severe criteria are met. 1

First-Line Antibiotic Selection

Adults

Amoxicillin-clavulanate 875 mg/125 mg twice daily is preferred over plain amoxicillin due to increasing prevalence of β-lactamase-producing organisms (H. influenzae and M. catarrhalis), which now account for 30-40% of cases. 1, 2, 4

Plain amoxicillin remains acceptable for:

• Mild disease: 500 mg twice daily 1, 4
• Moderate disease: 875 mg twice daily 1, 4
• Patients without recent antibiotic exposure (within past 4-6 weeks) 1, 4

Pediatric Patients (Ages 1-18)

• Standard-dose amoxicillin: 45 mg/kg/day divided into 2 doses for uncomplicated cases 3, 1
• High-dose amoxicillin: 80-90 mg/kg/day divided into 2 doses for high-risk children (age <2 years, daycare attendance, recent antibiotic use, or high local resistance rates) 3, 1
• Amoxicillin-clavulanate: 80-90 mg/kg/day of amoxicillin component with 6.4 mg/kg/day clavulanate in 2 divided doses for children with risk factors 3, 1

Treatment Duration

• Adults: 5-10 days, with most guidelines recommending treatment until symptom-free for 7 days (typically 10-14 days total) 1, 2, 4
• Children: 10-14 days 3, 1
• Shorter 5-7 day courses have comparable efficacy with fewer adverse effects for uncomplicated cases 1, 4

Penicillin-Allergic Patients

Non-Severe Allergy (Rash, Delayed Reaction)

Second- or third-generation cephalosporins are safe and effective:

• Cefuroxime-axetil (second-generation) 1, 2, 4
• Cefpodoxime-proxetil (third-generation) 1, 2, 4
• Cefdinir (third-generation) 1, 2, 4

The risk of cross-reactivity between penicillins and second/third-generation cephalosporins is negligible (<1%). 1

Severe Type I Hypersensitivity (Anaphylaxis)

• Respiratory fluoroquinolones: Levofloxacin 500 mg once daily or moxifloxacin 400 mg once daily for 10 days 1, 4, 5
• Doxycycline: 100 mg once daily for 10 days (acceptable alternative but has 20-25% predicted bacteriologic failure rate) 1

Do NOT use azithromycin or other macrolides due to resistance rates exceeding 20-25% for both S. pneumoniae and H. influenzae. 1

Reassessment and Treatment Failure

• Pediatric patients: Reassess at 72 hours 3, 1
• Adult patients: Reassess at 3-5 days 1, 2, 4

If no improvement or worsening occurs, switch to:

• High-dose amoxicillin-clavulanate: 2 g amoxicillin/125 mg clavulanate twice daily 1, 2
• Respiratory fluoroquinolones: Levofloxacin 500 mg once daily or moxifloxacin 400 mg once daily for 10 days 1, 5
• Third-generation cephalosporins: Cefpodoxime or cefdinir 1, 2

Essential Adjunctive Therapies

These improve outcomes regardless of antibiotic choice:

• Intranasal corticosteroids (mometasone, fluticasone, or budesonide twice daily) reduce mucosal inflammation and improve symptom resolution 1, 2
• Saline nasal irrigation provides symptomatic relief 1
• Analgesics (acetaminophen or NSAIDs) for pain and fever 1
• Short-term oral corticosteroids (typically 5 days) may be considered for patients with marked mucosal edema or severe pain who fail initial treatment 1

Critical Pitfalls to Avoid

• Never use first-generation cephalosporins (cephalexin, cefadroxil) due to inadequate coverage against H. influenzae 1
• Reserve fluoroquinolones as second-line therapy to prevent antimicrobial resistance—do not use as routine first-line treatment in patients without documented β-lactam allergies 1, 2, 4
• Do not prescribe antibiotics for viral rhinosinusitis lasting <10 days unless severe symptoms are present 1, 2
• Avoid inadequate treatment duration as this leads to relapse—complete the full course even after symptoms improve 1, 2
• Do not use topical decongestants >3 days due to risk of rhinitis medicamentosa 2

Watchful Waiting Option

For adults with uncomplicated acute bacterial sinusitis, watchful waiting without immediate antibiotics is appropriate when reliable follow-up can be assured. Start antibiotics only if no improvement occurs by 7 days or symptoms worsen at any time. 1, 4