What is the correct dose of paracetamol (acetaminophen) for a 9‑year‑old child?

Paracetamol Dosing for a 9-Year-Old Child

For a 9-year-old child, give paracetamol 15 mg/kg per dose (maximum 1000 mg) every 4-6 hours, not exceeding 4 doses in 24 hours or a total daily dose of 4000 mg. 1

Weight-Based Dosing Algorithm

The most accurate approach is weight-based dosing rather than age-based dosing, as age-based guidelines can lead to inappropriate dosing in up to 25% of children 2, 3:

• Calculate the dose: 15 mg/kg per single dose
• Maximum single dose: 1000 mg (for children >40 kg)
• Dosing interval: Every 4-6 hours as needed
• Maximum frequency: Not more than 4 doses in 24 hours
• Maximum daily dose: 4000 mg (60 mg/kg/day, whichever is less)

For a typical 9-year-old weighing approximately 27-32 kg, this translates to approximately 400-480 mg per dose.

Age-Based Approximation (If Weight Unknown)

If weight is unavailable, FDA labeling provides age-based guidance 1:

• Children 6 to under 12 years: 325 mg (10.15 mL of liquid formulation) every 4 hours
• Maximum: 5 doses in 24 hours

However, this age-based approach carries significant risk of underdosing in heavier children and overdosing in lighter children 2, 3.

Critical Dosing Considerations

The 15 mg/kg dose is essential for efficacy. Recent evidence demonstrates that older studies using subtherapeutic doses of ≤10 mg/kg showed paracetamol to be less effective than NSAIDs, but when dosed appropriately at 15 mg/kg, paracetamol is significantly more effective than placebo and at least as effective as NSAIDs for fever and pain management 4.

Common Pitfalls to Avoid

1. Underdosing: Children at the 91st percentile for weight receiving the lowest age-based dose will be undertreated 2
2. Overdosing: Children at the 9th percentile for weight receiving the highest age-based dose risk supratherapeutic levels 2
3. Exceeding maximum daily dose: The absolute maximum is 4000 mg/day in adults and children ≥12 years; for younger children, use 60-75 mg/kg/day (not to exceed 4000 mg) 1
4. Combination products: Always verify the child is not receiving paracetamol from other sources (combination cold medications, other caregivers) to prevent inadvertent overdose 1

Safety Thresholds

Hepatotoxicity risk thresholds 5:

• Acute ingestion requiring evaluation: ≥200 mg/kg or 10 g (whichever is less) within 24 hours
• Repeated supratherapeutic ingestion: ≥150 mg/kg/24h or 6 g/day (whichever is less) within 48 hours
• Chronic exposure: ≥100 mg/kg/24h or 4 g/day (whichever is less) for more than 48 hours

Documentation Recommendation

When administering multiple doses, carefully record all dose times to avoid accidentally exceeding the maximum recommended dose 6. This is particularly important when transitioning care between caregivers or healthcare settings.