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How to check your child’s temperature

Find out what to do when you think your child has a temperature or fever, and the type of thermometer to use.

A temperature of 38°C degrees Celsius (100.4°F) or above is high for a child.

High temperatures are often caused by common illnesses like colds, flus or mild infections. They usually get better within 3 days.

It's important to keep a close eye on your child and talk to your GP if you think their temperature could be something more serious.

Related topic

When to get medical help for your child

Find out what to do if your child has a high temperature

When to check your child's temperature

You should check your child’s temperature if they:

  • have flushed cheeks
  • feel hotter than usual on their chest, forehead, back or stomach
  • are sweaty
  • are more irritable than usual

How to check your child's temperature

The best way to check your child's temperature is with a digital thermometer. Ear or strip thermometers may not be as accurate. 

You can buy a digital thermometer at a pharmacy, supermarket or online. The thermometer will come with instructions.

Do not take your child's temperature immediately after a bath or when they're wrapped in warm clothing, as you will not get an accurate result.

Digital thermometer
Most digital thermometers are designed to be used in your child’s armpit. 

  1. Lie your baby flat or sit an older child comfortably on your knee.
  2. Put the thermometer in their armpit.
  3. Gently hold their arm against their side to keep the thermometer in place. The instructions that come with the thermometer will let you know how long you need to hold it for but many digital thermometers beep when they are ready.
  4. The display on the thermometer will tell you your child’s temperature. 

When to get medical help

Contact your GP or public health nurse if your baby:

  • is younger than 3 months old and has a temperature of more than 38°C
  • is older than 3 months and has a temperature of 39°C or more
  • has a temperature with other signs and symptoms

Trust your instincts. If you are worried about your child, always get medical help.

Do not use a mercury thermometer

Never use a mercury thermometer. They can break, exposing your child to glass splinters and mercury which is highly poisonous.

Do not use a mercury thermometer
Never use a mercury thermometer.

If your child is exposed to mercury

Call 01 809 2166 immediately if your child is exposed to mercury. The Poisons Information Line is open every day between 8am and 10pm.

Contact your nearest hospital emergency department (A&E) that treats children or call 999 if your child comes into contact with mercury outside of these hours.

Related topic

What to do if your child swallows poison

page last reviewed: 20/11/2018
next review due: 20/11/2021