Amoxicillin Dosing for Strep Throat in a 7-Year-Old Weighing 57 Pounds
For a 7-year-old child weighing 57 pounds (25.9 kg) with strep throat, give amoxicillin 50 mg/kg/day divided into 2 doses for 10 days, which equals approximately 650 mg twice daily (maximum 1000 mg per dose). 1
Weight-Based Calculation
- The child weighs 25.9 kg, requiring a total daily dose of 1,295-1,943 mg based on the recommended 50-75 mg/kg/day range 2, 1
- Practical dosing: Give 650 mg (approximately 13 mL of 250 mg/5 mL suspension) twice daily for 10 days 1
- This can also be dosed as 500 mg twice daily, which falls within the acceptable range and is easier to measure 2
- The maximum single dose should not exceed 1000 mg 1, 3
Treatment Duration and Formulation
- Complete the full 10-day course to prevent treatment failure, recurrence, and rheumatic fever complications 2, 3
- Amoxicillin is preferred over penicillin V in children due to better palatability and twice-daily dosing improves adherence 1
- Twice-daily dosing of amoxicillin is as effective as three or four times daily penicillin V 4, 5
Alternative Regimens
- Once-daily amoxicillin at 50 mg/kg (maximum 1000 mg) is an acceptable alternative if adherence is a concern, though twice-daily dosing remains standard 1, 5, 6
- For penicillin-allergic patients without anaphylaxis history, use narrow-spectrum cephalosporins (cephalexin or cefadroxil) for 10 days 2, 1
- For type I penicillin allergy, use clindamycin 20 mg/kg/day divided into 3 doses or azithromycin 12 mg/kg once daily for 5 days 2, 1
Clinical Monitoring
- Patients become non-contagious after 24 hours of antibiotic therapy 1
- Clinical improvement should occur within 48-72 hours; if not, reevaluate for complications or alternative diagnoses 1, 7
- Follow-up throat cultures are not routinely needed unless symptoms persist or recur 2
Common Pitfalls to Avoid
- Do not use amoxicillin-clavulanate (Augmentin) for uncomplicated strep throat as it is reserved for treatment failures or chronic carriers 3
- Avoid once-daily penicillin V, which has lower cure rates than more frequent dosing 4
- Do not prescribe courses shorter than 10 days for standard amoxicillin therapy, despite some evidence suggesting 5-7 day courses may be adequate 8
- Ensure proper suspension concentration verification (typically 250 mg/5 mL or 400 mg/5 mL) before calculating volume 1