What is the recommended dose of amoxicillin for an adult with bacterial sinus infection?

Amoxicillin-Clavulanate Dosing for Adult Bacterial Sinusitis

For adults with acute bacterial sinusitis, the recommended dose is amoxicillin-clavulanate 875/125 mg twice daily for 5-7 days, with high-dose amoxicillin-clavulanate (2000 mg amoxicillin component twice daily) recommended in areas with high pneumococcal resistance or for patients with risk factors for resistant pathogens. 1, 2

First-Line Therapy

Standard Dosing

• Amoxicillin-clavulanate 875/125 mg twice daily for 5-7 days 1, 2
• This is preferred over amoxicillin alone due to increasing prevalence of β-lactamase producing pathogens 1, 2

High-Dose Therapy Indications

High-dose amoxicillin-clavulanate (2000 mg amoxicillin component twice daily) should be used when:

• Patient lives in area with high prevalence (>10%) of resistant S. pneumoniae 2
• Recent antibiotic use (within past 4 weeks) 2
• Treatment failure with standard dosing 1
• Severe infection 3

Alternative Options for Penicillin-Allergic Patients

Non-Type 1 Allergy

• Cefuroxime 500 mg twice daily 1, 2
• Cefpodoxime 200-400 mg twice daily 1, 2

Type 1 Allergy (Anaphylaxis)

• Levofloxacin 500 mg once daily 2
• Moxifloxacin 400 mg once daily 2

Duration of Therapy

• 5-7 days for uncomplicated cases in adults 1
• Longer duration (10-14 days) may be needed for:
  • Severe infections
  • Immunocompromised patients
  • Treatment failure with initial therapy 1, 2

Adjunctive Treatments

• Intranasal corticosteroids (especially with history of allergic rhinitis) 1, 2
• Saline nasal irrigation 1-2 times daily 1, 2
• Acetaminophen for pain management 2
• Short-term decongestants if no contraindications 2

Clinical Pearls and Pitfalls

Important Considerations

• Take amoxicillin-clavulanate at the start of a meal to minimize gastrointestinal intolerance 3
• Assess for improvement within 3-5 days; consider alternative therapy if no improvement 2
• The most common bacterial pathogens in acute bacterial sinusitis are S. pneumoniae (30%), H. influenzae (30%), and M. catarrhalis (~10%) 2

Common Pitfalls

• Using amoxicillin alone when β-lactamase producing pathogens are common (H. influenzae and M. catarrhalis) 1
• Using inadequate dosing in areas with high resistance patterns 2
• Prescribing antibiotics for viral sinusitis (antibiotics should only be initiated once clinical diagnosis of bacterial sinusitis is established) 1
• Using trimethoprim-sulfamethoxazole or macrolides as first-line therapy due to high resistance rates 2

Warning Signs Requiring Specialist Referral

• Development of high fever, severe headache, visual changes
• Facial swelling or erythema
• Worsening symptoms despite appropriate antibiotic therapy 2

Recent clinical trials have shown that high-dose amoxicillin-clavulanate does not consistently show superior efficacy compared to standard dosing for most uncomplicated cases 4, but remains recommended in specific high-risk situations or areas with known high resistance patterns 2.