Paediatric Dose of Paracetamol
For children, use weight-based dosing of 10-15 mg/kg per dose every 4-6 hours, with a maximum daily dose not exceeding 75 mg/kg/day (or 4000 mg/day in adolescents), ensuring no more than 5 doses in 24 hours for children under 12 years.
Weight-Based Dosing (Preferred Method)
The most accurate and safe approach is weight-based calculation 1, 2:
- Single dose: 10-15 mg/kg per dose
- Dosing interval: Every 4-6 hours as needed
- Maximum daily dose: 75 mg/kg/day 3, 4
- Maximum number of doses: 5 doses per 24 hours for children under 12 years 1
Critical Maximum Daily Limits
Do not exceed 75 mg/kg/day - this is the current evidence-based maximum for postoperative pain and general use 3, 4. While some older guidelines suggested 80-90 mg/kg/day, recent evidence supports the lower 75 mg/kg/day threshold to prevent hepatotoxicity from repeated supratherapeutic dosing 4.
For adolescents ≥12 years: absolute maximum of 4000 mg (4 g) per day regardless of weight 1.
Age-Based Dosing (When Weight Unknown)
If weight is unavailable, the FDA-approved age-based dosing is 1:
- 2 to <4 years: 160 mg (5 mL) every 4 hours, max 5 doses/24h
- 4 to <6 years: 240 mg (7.5 mL) every 4 hours, max 5 doses/24h
- 6 to <12 years: 325 mg (10.15 mL) every 4 hours, max 5 doses/24h
- ≥12 years: 650 mg (20.3 mL) every 4-6 hours, max 6 doses/24h
- <2 years: Consult a doctor 1
Important Caveat About Age-Based Dosing
Age-banded dosing is problematic in clinical practice - a 2023 study found that 20% of hospitalized children would receive subtherapeutic doses and 4.3% would receive supratherapeutic doses using age-based dosing 5. The highest risk occurs in infants approaching 6 months (83% subtherapeutic) and children approaching 8 years (66% subtherapeutic). Always use weight-based dosing when the child's weight is known.
Repeated Supratherapeutic Dosing - Recognition and Thresholds
Liver injury from repeated dosing should be suspected when 4, 6:
- Child has received >75 mg/kg/day for ≥2 days, OR
- ≥150 mg/kg/24h for 48 hours, OR
- ≥100 mg/kg/24h for >48 hours
Risk factors that lower the threshold for toxicity include: fasting states, concurrent illness, chronic malnutrition, or concurrent use of enzyme-inducing medications 4.
Common Prescribing Pitfalls
Calculation errors with age-based dosing: Pharmacokinetic modeling shows that the manufacturer's 160 mg dose for ages 2-3 years is only effective for children at the lower weight limit (10.9 kg), not the upper limit (15.9 kg) 7.
Inadequate dosing: Up to 30% of febrile children receive inadequate doses at home due to age-based rather than weight-based dosing 7.
Exceeding daily maximums: The 10 mg/kg dose often fails to reach therapeutic plasma concentrations (10-20 μg/mL), while 15 mg/kg is more reliably effective 7, 2. However, prescribers must ensure the total daily dose stays ≤75 mg/kg/day.
Combining products: Always verify parents are not giving multiple acetaminophen-containing products simultaneously 1.
Hepatotoxicity Warning
Severe liver damage may occur if 1:
- Daily dose exceeds 75 mg/kg/day for >2 days
- Taken with other acetaminophen-containing drugs
- Taken with ≥3 alcoholic drinks daily (adolescents)
If liver injury is suspected (elevated transaminases or INR), start N-acetylcysteine immediately regardless of paracetamol concentrations 4.
Practical Prescribing Recommendation
Write prescriptions with: the child's weight, the calculated mg/kg dose, total daily dose in mg, number of divided doses, and duration of therapy 8. This reduces errors and unnecessary pharmacist consultations while ensuring safe dosing.