Fever in children: what counts, what to do, when to give medicine

Creator: OUMM
Published: 2026-09-29

Fever is a symptom, not an illness, and on its own is rarely dangerous. Treat the child, not the thermometer: how they look, whether they drink, and the red flags matter more than the number.

Written by OUMM

Last updated: 9 October 2026

What counts as a fever

Temperature	Name	What to do
37.1-37.9 °C	raised	watch, offer drinks
38.0-38.9 °C	fever	medicine only if the child is distressed (irritable, in pain, not drinking)
39.0-39.9 °C	high fever	contact a doctor; medicine if the child is distressed
≥ 40.0 °C	very high	contact a doctor; medicine if the child is distressed

Whatever the table says: a baby under 3 months at 38 °C or more: see a doctor urgently, also at night (see fever in babies); 3-6 months at 39 °C or more: see a doctor; fever for more than 3 days: see a doctor. Contacting a doctor at 39 °C or more in a child over 6 months is a cautious rule of this site, not a guideline threshold: NICE and the NHS use 39 °C only for babies aged 3-6 months, and in older children what counts is how the child is, the red flags and how long the fever lasts. The app and this site use the 38 °C threshold for every measuring method, without conversion, so log the method with each reading. The bands below 38 °C are the app's labels, not a clinical norm: a normal temperature depends on the measuring method and the child's age, so compare readings taken the same way.

When to give a fever medicine

NICE guidance: give medicine when the child is distressed (irritable, in pain, not drinking, not sleeping), not to chase a number. A playful child at 38.5 °C does not need it; a crying child with ear pain at 38.2 °C does. Take the dose from your product's leaflet table; see the dose calculator. What helps without medicine, and what not to do: how to bring down a child's fever.

Fluids

Fluids matter most: often, in small amounts, as much as your child wants. The figure below is an approximate daily water need including food and milk, not a target to drink.

Besides

Light clothing, room around 20 °C. No cold baths or alcohol rubs: they cause shivering and stress and do not lower the temperature for long.
Do not wake a sleeping child to measure.

How long is normal

A common viral infection gives 2-3 days of fever. More than 3 days, or fever returning after a fever-free day, deserves a visit. A few days of high fever in a young child followed by a rash may be roseola.

Febrile seizures

Affect 2-5% of children between 6 months and 5 years. They look frightening, usually last 2 to 3 minutes (NHS) and leave no damage. Lay the child on their side, put nothing in the mouth, time it. First seizure or one lasting over 5 minutes: call emergency services. Fever medicines do not prevent them.

Check the official source

These numbers are conversions from leaflets and guidelines. Before giving a medicine, confirm them at the source:

NHS: paracetamol for children · NHS: ibuprofen for children
NICE NG143: fever in under 5s · AAP HealthyChildren.org
Polish medicines register (URPL): official leaflets of the products listed here
Your own country's medicines regulator and the leaflet in the box always take precedence.

Tired of keeping track on a scrap of paper?
Oh Fever records what you gave and when. Free for one child.

iPhone and Apple Watch

Shows the time since the last dose, the doses recorded in 24 hours and the leaflet tables and sentences word for word, with a link to the official leaflet. It does not calculate or suggest doses.

Download on the App Store

Android

Also shows the row of the leaflet table for your child's weight and age, counts down to the next dose the leaflet allows and warns before the daily limit is crossed.

Get it on Google Play