Your body temperature is a good indicator of your health. If it's too high, it's a sign that your body is fighting off illness. Check to see if you have a fever by following these steps on how to use a thermometer.
Determine what type of thermometer you're using. There are several different types of thermometers that you can use to take your temperature. There is the traditional glass thermometer. It has a little red line inside of it that rises and falls according to your temperature. There is the more modern digital thermometer, which has a metal tip which reads your temperature and a display screen that tells you your temperature. And there are a myriad of forehead and ear thermometers (mostly used on children) that are used just like a digital thermometer. The type of thermometer you have will dictate its use, so make sure you know which kind you're using.
Prepare the thermometer. Before you use the thermometer, you need to prepare it. Whether it's old or new, you should always clean and sterilize the thermometer before using it. Some thermometers come with disposable tips that your throw out after each use, which is another option for keeping you and anyone else who uses the same thermometer germ-free.
Once the thermometer is clean, you will need to ensure it is ready for use. If you are using a glass thermometer, give it a real good shake. This will ‘reset' the red line inside of it. It's ready when the temperature line falls below 96 degrees. If you are using a digital thermometer, turn it on. Ensure that there is no error message and that the batteries don't need replacing.
Insert the thermometer. When the thermometer is ready to use, insert it into your mouth. It needs to sit under the tongue, which will require you to insert the thermometer more than half way into your mouth. It is fine to rest your tongue on the thermometer once it is inside of your mouth.
Allow the thermometer to take an accurate reading. The thermometer will require a little bit of time to read your temperature once it is inside of your mouth. Of course, this varies depending in what type of thermometer you're using. If you're using a glass thermometer, it needs to sit under your tongue for 3-5 minutes. Digital thermometers can take accurate temperature readings much faster. Just wait until the thermometer beeps, and then remove it from your mouth. (This should be about 20 seconds, maximum).
Read the temperature. Immediately after removing the thermometer from your mouth, you need to read your temperature. On the glass thermometer, follow the red line upward until it stops. Then read the number beside it. It will likely be a number with a decimal in it, like 98.8, or 101.2. If you're using a digital thermometer, finding out your temperature is as easy as looking at the display screen. For either type of thermometer, your temperature will only stay visible for a few seconds before it disappears (digital) or starts to drop because of the air temperature (glass). So remove and read the thermometer quickly each time you use it for the most accurate temperature results.