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.
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.
- Lie your baby flat or sit an older child comfortably on your knee.
- Put the thermometer in their armpit.
- 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.
- 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.
If your child is exposed to mercury
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.