Paracetamol Dosing for a 12-Year-Old Child Weighing 42 kg with Fever
For a 12-year-old child weighing 42 kg with fever, administer paracetamol 650 mg (20.3 mL of liquid formulation) every 4 to 6 hours, not exceeding 6 doses in 24 hours. 1
Weight-Based Dosing Recommendation
- The FDA-approved dosing for children 12 years and older is 650 mg every 4-6 hours, with a maximum of 6 doses per 24-hour period 1
- This translates to a maximum daily dose of 3,900 mg (approximately 93 mg/kg for a 42 kg child), which remains well below the toxic threshold 1
Alternative Weight-Based Calculation
- The optimal single dose based on pharmacokinetic data is 10-15 mg/kg per dose every 4-6 hours 2
- For a 42 kg child, this calculates to 420-630 mg per dose 2
- The recommended total daily dose should not exceed 90 mg/kg/day to avoid cumulative hepatic and renal toxicity 3
Practical Administration
- Use the age-based FDA dosing (650 mg per dose) as it is simpler and falls within the safe weight-based range for this child 1
- Available formulations include 325 mg tablets (give 2 tablets per dose) or liquid suspension at 20.3 mL per dose 1
- Maintain a minimum 4-hour interval between doses 1, 2
Important Safety Considerations
- Never exceed 6 doses in 24 hours (3,900 mg total daily) 1
- Carefully record all dose times to prevent accidental overdosing, particularly if multiple caregivers are involved 4
- The hepatotoxic threshold begins at doses exceeding 90-95 mg/kg/day with repeated administration 3
Comparative Efficacy Note
- If fever control is inadequate with paracetamol alone, ibuprofen (10 mg/kg per dose) may be considered as first-line therapy, as it provides superior antipyretic effect 4
- Combination therapy with both paracetamol and ibuprofen provides an additional 2.5 hours without fever over 24 hours compared to ibuprofen alone, but increases the risk of dosing errors 4