Up until the last 25 years, temperatures were frequently taken with glass mercury thermometers. Due to health and environmental considerations, the old mercury gauges are rare today. Modern thermometers are designed with safety and simplicity in mind. A temperature reading can usually be obtained in a few minutes or less.
Digital thermometers can be used orally, in the rectum or under the armpit to take a temperature. Wait until about a half hour after eating or drinking before inserting a digital thermometer in the mouth.
The very head of the device should be placed under the tongue. It’s important to keep lips together and breathe through the nose in order to get an accurate reading.
Depending on the brand of the thermometer, it will sound off a signal 30 seconds to one minute after insertion and display the temperature.
Standard thermometers can be used in the mouth or rectum. They won’t have as many bells and whistles as the digital variety, so don't expect to hear a beep when it’s ready to display a temperature.
The general rule of thumb is to keep an oral thermometer under the tongue and off to one side in a gently closed mouth for three minutes.
Always use a disposable cover and dispose of it promptly when finished. Wash both the thermometer and your hands thoroughly.
It’s important to refrain from using a disposable thermometer in the mouth after it’s been used to take a temperature rectally even if it has been thoroughly disinfected.
Thermometers tend to be user-friendly, but nevertheless it’s wise to follow the specific instructions that come with the testing device you plan to use.