What is the recommended dose of amoxicillin (amoxicillin) for treating bacterial sinusitis in adults?

Recommended Amoxicillin Dosing for Bacterial Sinusitis in Adults

For adults with bacterial sinusitis, amoxicillin-clavulanate is recommended over amoxicillin alone, with a standard dosage of 500 mg three times daily (every 8 hours) for 5-7 days. 1, 2

First-Line Treatment Options

• Amoxicillin-clavulanate is the preferred first-line treatment for acute bacterial rhinosinusitis (ABRS) in adults (weak recommendation, low-quality evidence) 2
• Standard adult dosing options include:
  • 500 mg three times daily (every 8 hours) for 5-7 days 1
  • 875 mg twice daily (every 12 hours) for 5-7 days 1
• The recommended duration of therapy for uncomplicated ABRS in adults is 5-7 days (weak recommendation, low-moderate quality evidence) 2

High-Dose Amoxicillin Considerations

• High-dose amoxicillin-clavulanate (2 g orally twice daily) should be considered in the following situations 2:
  • Geographic regions with high endemic rates of invasive penicillin-resistant Streptococcus pneumoniae (>10%)
  • Severe infection (high fever, systemic toxicity)
  • Age >65 years
  • Recent hospitalization
  • Recent antibiotic use within the past month
  • Immunocompromised state

Treatment Response Assessment

• Evaluate patient response after 3-5 days of amoxicillin therapy 1
• If symptoms worsen after 48-72 hours or fail to improve after 3-5 days, consider alternative management strategies 2
• For partial response (symptomatically improved but not back to normal), continue antibiotic treatment for another 10-14 days 2
• For poor response, switch to a broader-spectrum antibiotic 2

Adjunctive Therapies

• Intranasal saline irrigation with either physiologic or hypertonic saline is recommended as adjunctive treatment (weak recommendation, low-moderate quality evidence) 2
• Intranasal corticosteroids are recommended as an adjunct to antibiotics, primarily in patients with a history of allergic rhinitis (weak recommendation, moderate quality evidence) 2
• Neither topical nor oral decongestants and/or antihistamines are recommended as adjunctive treatment (strong recommendation, low-moderate quality evidence) 2

Evidence on Amoxicillin vs. Amoxicillin-Clavulanate

• Recent studies show that amoxicillin-clavulanate is more effective than amoxicillin alone for ABRS due to increasing prevalence of beta-lactamase-producing organisms 2
• A randomized clinical trial comparing high-dose vs. standard-dose amoxicillin-clavulanate found no significant difference in efficacy at day 3 (44.3% vs. 36.4% reporting "a lot better" or "no symptoms") 3
• However, another study found that immediate-release high-dose amoxicillin-clavulanate showed greater improvement at day 3 compared to standard dose (52.4% vs. 34.4%, p=0.04) 4

Common Pitfalls to Avoid

• Treating viral sinusitis with antibiotics is inappropriate and contributes to antibiotic resistance 1
• Not completing the full course of antibiotics can lead to incomplete eradication and potential relapse 1
• Failing to reassess treatment efficacy at 3-5 days may delay necessary changes in antibiotic therapy 1
• Not considering high-dose therapy in regions with high resistance patterns 2

Special Considerations

• For patients allergic to amoxicillin, alternatives include cephalosporins, macrolides, or quinolones 2
• Routine antimicrobial coverage for Staphylococcus aureus or MRSA during initial empiric therapy of ABRS is not recommended (strong recommendation, moderate quality evidence) 2
• In children with ABRS, a longer treatment duration of 10-14 days is recommended (weak recommendation, low-moderate quality evidence) 2