What is the recommended dose of paracetamol (acetaminophen) for a 12-year-old patient weighing 36 kilograms?

Paracetamol Dosing for a 12-Year-Old Weighing 36kg

For a 12-year-old patient weighing 36 kg, administer paracetamol 500-650 mg (approximately 15 mg/kg) every 4-6 hours, not exceeding 4 doses in 24 hours, with a maximum daily dose of 2400 mg (60 mg/kg/day). 1, 2

Weight-Based Dosing Calculation

• The standard pediatric dose is 10-15 mg/kg per dose every 4-6 hours 2, 3, 4
• For this 36 kg patient:
  • Minimum dose: 360 mg (10 mg/kg)
  • Optimal dose: 540 mg (15 mg/kg)
  • Practical dose: 500-650 mg per dose 1

Maximum Daily Limits

• Do not exceed 60 mg/kg/day (2160 mg for this patient) 2, 4
• The FDA-approved maximum for children ≥12 years is 650 mg per dose, not exceeding 6 doses in 24 hours (3900 mg/day) 1
• However, the safer pediatric maximum remains 60 mg/kg/day (approximately 2160 mg for 36 kg), which should take precedence 2, 4

Dosing Interval

• Administer every 4-6 hours as needed 1, 3
• Maximum of 4 doses in 24 hours is recommended for optimal safety 1, 5
• The 4-hour minimum interval prevents inadvertent overdosing 3

Practical Administration

• Paracetamol can be given without regard to meals, though administration with food may improve gastrointestinal tolerability 2
• Available formulations include tablets (typically 500 mg) and liquid suspension 1
• For a 36 kg child, adult formulations (500-650 mg tablets) are appropriate 1

Critical Safety Warnings

• Counsel parents to avoid all other products containing paracetamol, including over-the-counter cold remedies, to prevent inadvertent overdose 2, 6
• Single ingestions exceeding 150 mg/kg (5400 mg for this patient) are potentially hepatotoxic 5
• Chronic exposures greater than 140 mg/kg/day for several days carry risk of serious liver toxicity 5
• The recommended maximum of 60 mg/kg/day provides a substantial safety margin 4

Common Pitfalls to Avoid

• Do not use the adult maximum of 4000 mg/day as the ceiling for this patient—the pediatric weight-based maximum of 60 mg/kg/day (2160 mg) is safer 2, 4
• Carefully record all dose times to avoid accidentally exceeding the maximum recommended dose, especially if combining with other medications 6
• Be aware that many over-the-counter products contain paracetamol as a hidden ingredient 2

Clinical Context

• Paracetamol is recommended as first-line therapy for pain in children due to its superior safety profile compared to NSAIDs 7
• It is effective for mild to moderate pain and fever management 5, 4
• The analgesic effect typically lasts 4-6 hours 4