What is the recommended dose of amoxicillin (amoxicillin) for acute sinusitis?

Amoxicillin Dosing for Acute Sinusitis

For adults with acute bacterial sinusitis, the recommended dose of amoxicillin is 500 mg three times daily or 875 mg twice daily for 5-7 days. 1

Adult Dosing Options

• Standard dosing options for adults with acute bacterial sinusitis include:

  • Amoxicillin-clavulanate 500 mg three times daily for 5-7 days 1
  • Amoxicillin-clavulanate 875 mg twice daily for 5-7 days 1, 2
  • For more severe infections and respiratory tract infections, 875 mg/125 mg amoxicillin-clavulanate tablet every 12 hours is recommended 2

• For patients with difficulty swallowing, liquid formulations can be substituted:

  • 125 mg/31.25 mg per 5 mL or 250 mg/62.5 mg per 5 mL suspension can replace the 500 mg/125 mg tablet 2
  • 200 mg/28.5 mg per 5 mL or 400 mg/57 mg per 5 mL suspension can replace the 875 mg/125 mg tablet 2

Pediatric Dosing

• For children with acute sinusitis, dosing is weight-based:
  • Children ≥12 weeks (3 months): 45 mg/kg/day divided every 12 hours for more severe infections 2
  • Children weighing 40 kg or more should follow adult dosing recommendations 2
  • In one study, amoxicillin 80 mg/kg/day in 3 divided doses for 14 days showed better cure rates at day 3 compared to placebo (85% vs. 37.5%) 3

Duration of Treatment

• The recommended duration for acute bacterial sinusitis treatment is 5-7 days for adults 1
• Treatment should be continued until the patient has been symptom-free for approximately 7 days, generally completing a 10-14 day course 4
• Patient response should be evaluated after 3-5 days of therapy; if improving, continue treatment to complete the course 4

Special Considerations

• For patients with renal impairment:

  • Patients with glomerular filtration rate <30 mL/min should not receive the 875 mg/125 mg dose 2
  • Patients with GFR 10-30 mL/min should receive 500 mg/125 mg or 250 mg/125 mg every 12 hours 2
  • Patients with GFR <10 mL/min should receive 500 mg/125 mg or 250 mg/125 mg every 24 hours 2

• For patients not responding to initial therapy:

  • If no improvement is observed after 3-5 days, consider switching to a different antibiotic 4
  • Recent research has shown conflicting results regarding high-dose versus standard-dose amoxicillin for sinusitis:
    • One study found high-dose immediate-release amoxicillin showed better improvement at day 3 compared to standard dose (52.4% vs. 34.4%) 5
    • However, a more recent 2021 study found no benefit of high-dose compared to standard-dose amoxicillin-clavulanate (36.4% vs. 44.3% improvement at day 3) 6

Common Pitfalls to Avoid

• Stopping antibiotics prematurely when symptoms improve can lead to incomplete eradication and potential relapse 4
• Failing to reassess treatment efficacy at 3-5 days may delay necessary changes in antibiotic therapy for non-responders 4
• Using antibiotics for viral upper respiratory infections is inappropriate, as studies show antibiotics do not significantly reduce symptom burden in post-viral rhinosinusitis 3
• Be aware that antibiotic treatment is associated with more adverse events compared to placebo, with gastrointestinal side effects being most common 3, 6