Paediatric Dosage Calculations

Paediatric Dosage Calculations

Paediatric dosages differ from adults because the paediatric patient has a different body mass and metabolism rate.

The child’s weight and size is extremely important when administrating medications since every child is unique and weights may vary drastically.  Even children the exact same age may have extreme weight differences. 

Children’s dosage calculations should always be double checked to ensure it is within the safe range.  It is common to round down when calculating since the risk of overdose in paediatrics is so dangerous. 

Dosages Based on Body Size

These calculations can be based on weight (Kg or lbs) or BSA (m2)

Ensuring the Order is Within Safe Range

When administrating medications to a paediatric patient always refer to the drug sheet to ensure the dose prescribed is within the safe range for your sized patient.  If the dose is above or below the recommended safe range do not give the medication and consult the prescribing physician. 


IV Medications 

In paediatrics it is common to use a volume-control-chamber when administrating medications via IV. This ensures the patent does not receive too much fluid and experience fluid overload. 

Children are very sensitive to high levels of hydration as well as low levels of hydration so it is very important to monitor for symptoms of fluid overload and dehydration. 

The daily fluid maintenance needs is the amount of fluid a child needs over a period of 24 hours. This depends on the weight of the child.  This is for a normal functioning child, any additional loses of fluid from diarrhea or vomiting need to be replaced further based on individual condition. 


Paediatric Daily Fluid Maintenance Formula

First 10 kg of body weight: 100 mL/kg

Next 10 Kg of body weight: 50 mL/kg 

For each Kg above 20 kg of body weight: 20 mL/kg


Nice to now: when giving medications that must be given orally mixed in food or liquid. Do not give in essential foods or fluids. Giving the medication in a child’s favourite food may cause them to refuse eating it in the future! 

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