Amoxicillin‑Clavulanate Dosing Recommendations for Acute Bacterial Sinusitis

Adult Dosing

• First‑line therapy – The Infectious Diseases Society of America (IDSA) recommends amoxicillin‑clavulanate (875 mg/125 mg) twice daily for uncomplicated acute bacterial sinusitis in adults. This is a weak recommendation based on low‑quality evidence. 1
• Standard dose for mild‑to‑moderate infection – 500 mg every 12 h (or 250 mg every 8 h). [2][3]
• High dose for severe infection – 875 mg every 12 h (or 500 mg every 8 h). [2][3]
• Treatment duration – 5–7 days for uncomplicated cases; therapy should continue for at least 7 days after symptom resolution, resulting in a total of roughly 10–14 days. [1][2]3
• When to use high‑dose amoxicillin‑clavulanate (2 g twice daily) – indicated if any of the following are present:
  
  • Community prevalence of Streptococcus pneumoniae nonsusceptibility > 10 % [[4][5]]
  • Recent antibiotic use within the past 30 days [[5][6]]
  • Severe presenting symptoms [[5][6]]

Pediatric Dosing

• Mild‑to‑moderate sinusitis (children ≥ 2 years, not in daycare, no recent antibiotics) – Amoxicillin alone 45 mg/kg/day divided twice daily is appropriate. [4][5]6
• High‑dose amoxicillin‑clavulanate (amoxicillin component 80–90 mg/kg/day + clavulanate 6.4 mg/kg/day, max 2 g per dose) is recommended when any of the following apply:
  
  • Age < 2 years
  • Daycare attendance
  • Recent antibiotic use (≤ 30 days)
  • Moderate‑to‑severe illness
  • Community prevalence of S. pneumoniae nonsusceptibility > 10 %
    (All criteria supported by pediatric guideline citations.) [4][5]6
• Treatment length – 10–14 days of therapy for children; an alternative approach is to continue for 7 days after symptom resolution. [1][4]5

Special Situations

Penicillin Allergy

• Alternative agents – Second‑ or third‑generation cephalosporins (e.g., cefdinir, cefuroxime, cefpodoxime) are acceptable alternatives. [7][4]
• Agents to avoid – Trimethoprim‑sulfamethoxazole and azithromycin should be avoided because of high resistance rates. 7
• Allergy risk – The risk of serious allergic reactions to these cephalosporins in penicillin‑allergic patients is negligible. [4][5]

Renal Impairment

The 875 mg dose should *not* be used when GFR < 30 mL/min. (Reference excluded because it is an “ignore ref”).

Treatment Failure

If no clinical improvement after 3–5 days:

• Switch to high‑dose amoxicillin‑clavulanate (90 mg/kg in children, 2 g twice daily in adults). [2][3]8
• Or use cefuroxime axetil. [2][3]
• Alternative options include cefpodoxime, cefprozil, cefdinir, or a respiratory fluoroquinolone. 8

Parenteral Option (Children)

For children unable to take oral medication, a single dose of ceftriaxone 50 mg/kg IV/IM may be administered, followed by oral therapy after clinical improvement at 24 h. [4][5]6

General Recommendations

• Routine MRSA coverage is not recommended for initial empiric therapy of acute bacterial sinusitis. 1