What is the recommended dose of Amoxil (amoxicillin) for a child with strep throat weighing 65 pounds?

Amoxicillin Dosing for Strep Throat in a 65-Pound Child

For a child weighing 65 pounds (approximately 29.5 kg) with strep throat, administer amoxicillin 50 mg/kg once daily (1,475 mg, rounded to 1,500 mg) or 25 mg/kg twice daily (approximately 740 mg/day divided into two 370 mg doses) for 10 days. 1, 2

Weight-Based Calculation

• Child's weight: 65 pounds = 29.5 kg
• Once-daily dosing: 50 mg/kg × 29.5 kg = 1,475 mg once daily (can round to 1,500 mg) 1, 2
• Twice-daily dosing: 25 mg/kg × 29.5 kg = 738 mg/day, divided into two doses of approximately 370 mg each 1, 2
• Maximum dose: Do not exceed 1,000 mg for once-daily dosing or 500 mg per dose for twice-daily dosing 1, 2

Recommended Regimen for This Patient

Since this child weighs less than 40 kg, the appropriate dose is 1,000 mg once daily (the maximum for once-daily dosing) or 500 mg twice daily (the maximum per dose for twice-daily dosing) for 10 days. 1, 2, 3

Evidence Supporting Once-Daily Dosing

• Once-daily amoxicillin at 50 mg/kg (maximum 1,000 mg) demonstrates equivalent efficacy to multiple-daily penicillin V regimens for clinical and bacteriologic cure 4, 5
• Once-daily dosing improves compliance without compromising treatment outcomes 4, 5
• The American Heart Association and IDSA support once-daily amoxicillin as a preferred first-line treatment 2

Critical Treatment Considerations

• Duration: Complete the full 10-day course regardless of symptom resolution to prevent acute rheumatic fever 1, 2, 3
• Administration: Give at the start of a meal to minimize gastrointestinal intolerance 3
• Treatment failure: If the patient fails initial therapy, consider amoxicillin/clavulanate (Augmentin) at 40 mg/kg/day of the amoxicillin component divided into three doses (maximum 2,000 mg/day) for chronic carriers or treatment failures 1, 2

Alternative Dosing Options

If twice-daily dosing is preferred for clinical reasons:

• 500 mg twice daily for 10 days is an acceptable alternative regimen 3

Common Pitfalls to Avoid

• Underdosing: Historical lower doses of penicillin V have shown inferior bacteriologic cure rates (54.5%) compared to amoxicillin 40 mg/kg/day (79.3%) 6
• Early discontinuation: Stopping treatment when symptoms resolve (typically 48-72 hours) increases risk of rheumatic fever 3
• Incorrect weight conversion: Always verify pound-to-kilogram conversion (divide pounds by 2.2) to avoid dosing errors

Penicillin Allergy Alternatives

If the patient has a documented penicillin allergy:

• Cephalexin: 20 mg/kg/dose twice daily (maximum 500 mg/dose) for 10 days 2
• Clindamycin: 7 mg/kg/dose three times daily (maximum 300 mg/dose) for 10 days for type I hypersensitivity 2
• Azithromycin: 12 mg/kg once daily (maximum 500 mg) for 5 days, though use with caution due to resistance concerns 2