What is the appropriate co‑amoxiclav (amoxicillin + clavulanic acid) dose per kilogram for a child with a post‑operative infection?

Co-Amoxiclav Post-Operative Dosing for Children

For post-operative prophylaxis or treatment in children, administer co-amoxiclav at 45 mg/kg/day of the amoxicillin component divided into two doses (22.5 mg/kg per dose twice daily), or 90 mg/kg/day divided into two doses (45 mg/kg per dose twice daily) for severe infections or when resistant organisms are suspected. 1

Standard Pediatric Dosing Algorithm

For Uncomplicated Post-Operative Infections

• Standard dose: 45 mg/kg/day of amoxicillin component with 6.4 mg/kg/day of clavulanate, divided into 2 doses (every 12 hours). 1
• This translates to approximately 22.5 mg/kg per dose of the amoxicillin component given twice daily. 1
• Duration: 5–7 days for most post-operative infections. 2, 1

For Severe or Complicated Post-Operative Infections

• High dose: 90 mg/kg/day of amoxicillin component with 6.4 mg/kg/day of clavulanate, divided into 2 doses. 1, 3
• This translates to 45 mg/kg per dose of the amoxicillin component given twice daily. 1
• Maximum daily dose: Do not exceed 4000 mg/day of amoxicillin. 1

Risk Factors Requiring High-Dose Regimen

Use the 90 mg/kg/day regimen when any of these factors are present:

• Age < 2 years 1
• Recent antibiotic use (within past 30 days) 1, 4
• Daycare attendance 1
• Moderate-to-severe infection 1
• Suspected resistant organisms (particularly penicillin-resistant Streptococcus pneumoniae or β-lactamase-producing organisms) 1, 5
• Immunocompromised status 1
• Failed previous antibiotic therapy 1

Practical Dosing Examples

For a 20 kg child:

• Standard dose: 450 mg amoxicillin component twice daily (22.5 mg/kg × 20 kg)
• High dose: 900 mg amoxicillin component twice daily (45 mg/kg × 20 kg)

For a 10 kg child:

• Standard dose: 225 mg amoxicillin component twice daily
• High dose: 450 mg amoxicillin component twice daily

Intravenous Dosing (If Oral Route Not Feasible)

• Standard IV dose: 30 mg/kg of amoxicillin component every 6–8 hours. 3
• Severe infections: Up to 200 mg/kg/day of amoxicillin component divided every 6 hours. 3
• Switch to oral as soon as the child can tolerate oral intake and shows clinical improvement (typically within 24–48 hours). 2, 3

Critical Prescribing Considerations

• The 14:1 ratio formulation (90 mg/kg amoxicillin with 6.4 mg/kg clavulanate) causes less diarrhea than older formulations with higher clavulanate content. 1
• Do not substitute two lower-strength tablets for one higher-strength tablet, as this results in excessive clavulanate dosing and increased gastrointestinal side effects. 6
• Reassess at 48–72 hours: If no clinical improvement, consider escalating to high-dose regimen or alternative antibiotic. 1, 3
• Renal impairment: Reduce dosing frequency proportionally based on creatinine clearance; specific pediatric renal dosing guidelines are limited, so apply adult adjustments pragmatically. 3

Common Pitfalls to Avoid

• Underdosing in high-risk patients: Failing to use the 90 mg/kg/day regimen when risk factors are present leads to treatment failure rates of 20–25%. 1
• Incorrect weight-based calculations: Always verify that the amoxicillin component (not the total tablet weight) is used for dosing calculations. 1
• Premature discontinuation: Complete the full 5–7 day course even if symptoms improve earlier to prevent relapse and resistance. 2, 1
• Using adult dosing for children ≥40 kg: Transition to adult dosing (875 mg/125 mg twice daily) only for children weighing ≥40 kg. 1