For advice about taking a temperature in a child under 5, see how to take your baby's temperature.
Using a digital thermometer
One way to check your temperature is to use a digital thermometer. You can buy these from supermarkets and pharmacies.
To use a digital thermometer:
- Clean the tip with cold water and soap, then rinse it.
- Turn the thermometer on.
- Put the tip under your tongue, towards the back of your mouth.
- Close your lips around the thermometer.
- Wait until it beeps or flashes.
- Check the temperature on the display.
You can also use a digital thermometer in your armpit. Make sure you keep your arm tight against your body until the thermometer beeps or flashes.
Digital ear thermometers
If you use a digital ear thermometer, follow the instructions that come with it.
You usually need to gently pull your ear up and back before putting the thermometer in your ear. This helps you get a more accurate temperature.
Other thermometers
Do not use a glass thermometer, infrared thermometer or a forehead strip.
Glass thermometers can be dangerous.
Some infrared thermometers available to buy do not meet UK regulations and may not be suitable to use.
Forehead strips are not accurate.
If you do not have a thermometer
You can often still tell if you have a high temperature even if you do not have a thermometer.
Touch your chest and back. If they feel hotter than usual, you may have a high temperature. Touch is the least accurate way of checking a temperature. You may also have other symptoms such as feeling shivery (chills).
Touching your forehead is not a very accurate way of checking your temperature.
What is a high temperature?
Normal body temperature is different for everyone and changes during the day.
A temperature of 38C or more is usually considered a high temperature (fever).
Important
It's not always easy to take a temperature accurately.
If you feel cold or shivery, sometimes followed by hot, flushed skin and sweating, you may have a high temperature even if a thermometer says your temperature is below 38C.
What should I do if I have a high temperature?
If you think you have an illness like flu, try to stay at home and avoid contact with other people if you have a high temperature or do not feel well enough to do your normal activities.
Use the NHS 111 online service to find out what to do.
If you think you need medical help right now, NHS 111 online can tell you what to do next.
Call NHS 111 if you cannot use the online service or because you need help for a child under 5.