Weight-Based Dosing in Children
Paediatric dosing is weight-based, not a fraction of an adult dose guessed by eye. This article covers the calculation, the tools, and the common errors that put children at risk.
Calculating the dose
Most paediatric doses are expressed as mg per kg per dose, or mg per kg per day divided into doses. Always confirm the child's current weight — it changes rapidly in young children. Calculate the dose, then verify it falls within the safe range for the child's age and weight before dispensing.
If the calculated dose exceeds the adult maximum, cap it at the adult dose. This is a common safety check that prevents overdose in larger children.
Liquid doses and measuring tools
The most common paediatric error is giving the wrong volume of a liquid medicine. A household spoon is not a measuring tool — use an oral dosing syringe or the measuring cup that comes with the product. Counsel the parent on exactly how many mL to give, and demonstrate with the syringe.
Concentrations vary between products: paracetamol comes in multiple strengths. Always check the concentration on the bottle, not just the drug name, before calculating the volume.
Practical example
Paracetamol for a 14 kg child
A parent asks for paracetamol for a 14 kg child. The dose is 15 mg/kg, so 210 mg per dose. The bottle is 120 mg/5 mL, so the parent needs 8.75 mL — measured with a syringe, not a spoon. The pharmacist writes the dose and interval on the bottle and demonstrates the syringe. The child gets the right dose, not a guessed spoonful.
Key takeaways
- Paediatric doses are mg/kg — always confirm the current weight.
- Cap at the adult maximum dose for larger children.
- Use a dosing syringe, never a household spoon.
- Check the concentration on the bottle — it varies between products.
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