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Fever in children, by weight and by age
What counts as a fever at each age, the weight-based paracetamol and ibuprofen tables with the daily ceilings, how to look after a feverish child, and the red flags that mean call now instead of waiting.
This is a reference, not a prescriber: the package insert of the bottle in your hand outranks every number on this page, aspirin is never for children, and in a baby under three months any measured fever is urgent — call now, do not dose. If the child is on other medicines, or has a known liver, kidney or stomach condition, dosing belongs to a clinician.
How to read this
Fever in children is mostly a numbers problem with one twist: the numbers are weight-based, not age-based, and the dangerous part is usually the dosing errors and the missed red flags rather than the temperature itself. The seven pages below follow the order a worried parent actually needs them: is it a fever, how do I measure it, how much of each medicine, when is it not a home case, how do I look after them, and what if they seize.
The two rules that prevent nearly every dosing error
First: the dose is the child's weight, not the child's age. Two children of the same age can differ by half in weight, and every paediatric formulation prints a weight ladder for exactly that reason. Second: the daily ceilings are as much a rule as the single doses — four paracetamol doses a day at most, three ibuprofen doses a day at most — and the classic overdose is stacking two products that both contain paracetamol. Read the ingredient list of everything given.
And the one rule that overrides both: in a baby under three months, any measured fever is urgent, and the treatment is a call, not a dose.
Fever thresholds and red flags: the national paediatric guidance in the region. Dosing: the standard weight-based rules — paracetamol 15 mg/kg per dose every 4–6 hours, at most four doses a day (60 mg/kg/day ceiling); ibuprofen 10 mg/kg per dose every 6–8 hours, at most three doses a day (30 mg/kg/day ceiling), from 3 months and about 5 kg. Febrile seizures: the standard paediatric emergency guidance (simple vs complex, the five-minute line). Checked 2026-09-06.
Frequently asked questions
What counts as a fever?
A core temperature of 38 °C or more, with the measurement site as part of the number — an armpit reading runs about half a degree below the core, so 37.5 °C under the arm is a core fever. Rectal measurement is the reference, and it is the only site reliable enough for the under-three-month rule.
How much paracetamol do I give a child?
By weight, not age: 15 mg per kilogram per dose, every 4 to 6 hours, and never more than four doses in 24 hours — a 60 mg/kg daily ceiling. A 10 kg child gets 150 mg per dose. Read the ingredient list of everything you give, because the classic overdose is two paracetamol products stacked.
How much ibuprofen do I give a child?
10 mg per kilogram per dose, every 6 to 8 hours, at most three doses a day — a 30 mg/kg daily ceiling — from 3 months of age and about 5 kg of weight. Give it with food or milk. Ibuprofen is avoided in chickenpox and in a dehydrated child, and aspirin is never for children with a fever.
When should I call instead of treating at home?
Under three months, any measured fever: call now. Three to six months, any fever above 38.5 °C or any fever with poor feeding, drowsiness or a rash. Any age: a fever past three full days, or any of the urgent combinations — the rash that does not fade under a glass, the stiff neck, breathing trouble, a seizure, or a child who cannot be roused.
Should I treat the fever or the child?
The child. Fever is the immune system working and is not dangerous at ordinary heights; the medicine is for the child's comfort, at the weight-based dose, when the fever is costing them comfort. Fluids matter more than the number on the thermometer.
Log the numbers, not the panic
TempoLife keeps a symptom and medicine log with timestamps, so the doctor's four questions — age, weight, readings, medicines given — are already answered when you call.