What is the recommended dosing of amoxicillin (amoxicillin) for a sinus infection?

Amoxicillin Dosing for Sinus Infection

For acute bacterial sinusitis, the recommended dosage of amoxicillin is 875 mg twice daily for 5-7 days, with high-dose amoxicillin-clavulanate (2000 mg amoxicillin component twice daily) reserved for patients with risk factors for resistant organisms. 1

Standard Dosing Regimen

• First-line therapy:

  • Amoxicillin-clavulanate 875/125 mg twice daily for 5-7 days 1
  • This is the preferred treatment according to the American Academy of Otolaryngology-Head and Neck Surgery guidelines

• Duration:

  • 5-7 days is typically sufficient for uncomplicated cases 1
  • Shorter courses (5-7 days) may be as effective as longer courses with fewer side effects

High-Dose Regimen Considerations

High-dose amoxicillin-clavulanate should be considered for patients with risk factors for resistant organisms, including:

• Recent antibiotic use (within past month)
• Age >65 years
• Healthcare exposure
• Immunocompromised state
• High local prevalence of resistant bacteria 1

In these cases, the recommended dosage is:

• High-dose amoxicillin-clavulanate with 2000 mg of the amoxicillin component twice daily for 5-7 days 1

Evidence on Standard vs. High-Dose Regimens

Recent clinical trials have produced mixed results regarding the superiority of high-dose versus standard-dose amoxicillin:

• A 2018 study found that immediate-release high-dose amoxicillin led to more rapid improvement compared to standard-dose (52.4% vs 34.4% improvement at day 3), but with increased risk of severe diarrhea (15.8% vs 4.8%) 2

• However, a more recent 2021 study found no benefit of high-dose compared to standard-dose amoxicillin-clavulanate, with similar rates of improvement (36.4% vs 44.3%) and similar rates of severe diarrhea (7.7% vs 7.0%) 3

Treatment Failure Protocol

If a patient fails to respond to initial therapy within 72 hours:

1. Reassess the diagnosis
2. Consider switching to:
   • A respiratory fluoroquinolone (levofloxacin or moxifloxacin)
   • High-dose amoxicillin-clavulanate (if not already prescribed)
   • Combination therapy with clindamycin plus cefixime 1

Alternative Options for Penicillin-Allergic Patients

For patients with penicillin allergy, consider:

• Cefuroxime 500 mg twice daily for 5-7 days
• Cefpodoxime 200-400 mg twice daily for 5-7 days
• Cefdinir 14 mg/kg/day divided once or twice daily for 5-7 days 1

Monitoring and Follow-up

• Instruct patients to follow up if symptoms persist beyond 72 hours of treatment
• Reassess diagnosis after 72 hours if symptoms persist or worsen
• Consider switching antibiotics if no improvement after 72 hours 1

Common Side Effects

• Diarrhea (most common)
• Nausea
• Abdominal pain
• Vaginitis in female patients 4, 5, 6

High-dose regimens may be associated with higher rates of severe diarrhea compared to standard dosing 2, 3.