Normal body temperature is often defined as 37 degrees Celsius (C). Whenever a person is ill or feels hot or cold to the touch, it is important to take their temperature. If a doctor is called during an illness, he or she will often ask for the temperature of the ill person.
Temperature is often not a reliable sign in the elderly or those on oral steroids.
Who is a candidate for the procedure?
A person's temperature may be checked when fever, or higher-than-normal body temperature, is suspected. Examples of conditions that might cause fever include: A person who might have hypothermia, or an abnormally low body temperature, can also have their temperature measured. Hypothermia is usually caused by being in the cold for too long.
How is the procedure performed?
There are 4 common methods for taking a temperature:
Temperature strips, which are liquid crystal strips applied to the forehead, and temperature-sensitive pacifiers may not be as accurate as a regular thermometer. If these are used, a child may have a fever despite a "normal" reading.
- in the mouth, which is known as an oral temperature
- in the anus, which is called a rectal temperature
- in the armpit, which is known as an axillary temperature
- in the ear, which is called a tympanic temperature
A baby's temperature can be taken either in the anus or in the armpit. It would be dangerous to take an oral temperature on a baby, who might bite the thermometer. Taking a baby's temperature in the ear may be difficult. Parents should check with the baby's doctor for the best method and what temperatures should be reported.
Temperature can be taken in the mouth in children over the age of 4 years as long as they follow instructions.
How to Take an Oral Temperature:1. For accuracy, wait at least 10 minutes after hot or cold fluids have been taken, or cigarettes have been smoked.
2. Select a glass thermometer that has a "bulb" or silver end that is long and thin. If using a digital thermometer, make sure it is in the correct "on" mode.
3. Gently shake the mercury, or silver line, on the glass thermometer down below 35 degrees Celsius.
4. Place the thermometer in the person's mouth under the tongue on one side, and slide well back into the mouth. Have person close the lips, and to avoid biting the thermometer.
5. Hold thermometer in place for 3 to 4 minutes.
6. Remove the thermometer from the mouth and read it. On a digital thermometer, simply read the numbers. On a glass thermometer, hold it horizontally and turn it slowly until the temperature at the highest position of the mercury column can be read. The space between the larger marks is one degree; the space between the short marks is 0.2 degrees (or two tenths of a degree).
How to Take a Rectal Temperature:1. Select a rectal glass thermometer, which has a rounder bulb at the end, or use a digital thermometer.
2. Shake the mercury on the glass thermometer down below 35 degrees Celsius.
3. Moisten the lower portion of the thermometer with Vaseline or other lubricant.
4. Place the infant on his/her stomach, on a firm surface, or across your lap.
5. Spread the buttocks to expose the anal opening. Hold the thermometer one inch from the bulb, and gently insert it into the rectum. Insert the thermometer just far enough that the bulb, or silver tip, is completely covered. Do not insert thermometer more than one inch.
6. Do not let go of the thermometer. Carefully hold it in place for 3 to 4 minutes.
7. Remove the thermometer gently and read it. Rectal temperatures are generally 0.5 to 1 degree C higher than oral temperatures.
How to Take an Axillary Temperature:1. Use a glass or digital thermometer. Make sure the mercury on the glass thermometer is under 35 degrees Celsius. before taking the temperature.
2. Hold the thermometer in the clean, dry armpit, making sure that the bulb is completely covered between the person's arm and side. Hold the arm down.
3. Hold the thermometer in position for 3 to 4 minutes.
4. Remove the thermometer and read the temperature. Normal axillary temperatures are 1 degree C lower than oral temperatures.
How to Take a Tympanic Temperature:1. Use a thermometer especially designed for ear temperatures.
2. Hold the thermometer firmly at the opening to the child's ear, and press the button.
3. Remove the thermometer and read the temperature.
What happens right after the procedure?
After the procedure, wash the thermometer with cold, soapy water or alcohol. Rinse it in cool water. After drying it, put it away in a safe place out of the reach of children.
What happens later at home?
Temperatures should be written down, along with time and date. The temperature might be reported to the doctor, along with other symptoms. The temperature should be checked often during illness.
What are the potential complications after the procedure?
Rectal thermometers can cause tissue damage if not used properly. Glass thermometers might break, also causing injury.
Author: Barbara Mallari, RN, BSN, PHN
Reviewer: eknowhow Medical Review Panel
Editor: Dr John Hearne
Last Updated: 3/02/2005
Potential conflict of interest information for reviewers available on request