High temperature (fever) in adults

What is a high temperature?

Normal body temperature is different for everyone and changes during the day.

A high temperature is usually considered to be 38C or above. This is sometimes called a fever.

Check if you have a high temperature

You may have a high temperature if:


If you feel hot or shivery, you may have a high temperature even if a thermometer says your temperature is below 38C.

Do I need to take my temperature?

You do not need to take your temperature using a thermometer, but you can if you have one.

Make sure you use it correctly to help get an accurate result. See how to take a temperature.

Treating a high temperature

If you have a high temperature, it can help to:

Causes of a high temperature

Many things can cause a high temperature. It's not usually a sign of anything serious.

It's often just caused by your body fighting an infection, such as a cold or flu.

Sometimes it could be a sign of something more serious if your temperature is very high or will not come down.


Advice for children

This page is for adults. For advice about children, see high temperature (fever) in children.

Page last reviewed: 6 April 2020
Next review due: 6 April 2023