The best way to measure a child's temperature depends upon several factors. In all children, a rectal temperature is the most accurate. However, it is possible to accurately measure the temperature in the mouth (for children older than four or five years) or ear (for children older than six months) when the proper technique is used.
Temperatures measured in the armpit are the least accurate, but may be useful as a first test in an infant who is younger than three months. If the armpit temperature is over 99ºF (37.2ºC), the rectal temperature should be measured.
It is not accurate to measure a child's temperature by feeling the child's skin. This is called a tactile temperature, and it is highly dependent upon the temperature of the person who is feeling the child's skin.
Glass versus digital thermometers
Digital thermometers are inexpensive, widely available, and are the most accurate way to measure temperature. A variety of styles are available.
Glass thermometers that contain mercury are not recommended due to the potential risks of exposure to mercury (which is toxic) if the thermometer is broken. If a digital thermometer is not available, be sure to carefully "shake down" the glass thermometer before use. Instructions for disposing of thermometers that contain mercury are available online (www.epa.gov/mercury/spills/index.htm).
Other types of thermometers are available, including plastic strip, forehead, and pacifier thermometers. However, these are not as accurate as digital thermometers and are not recommended.
Rectal temperature
- The child or infant should lie down on their stomach across an adult's lap.
- Apply a small amount of petroleum jelly (eg, Vaseline) to the end of the thermometer.
- Gently insert the thermometer into the child's anus until the silver tip of the thermometer is not visible (1/4 to 1/2 inch inside the anus).
- Hold the thermometer in place.
- A glass thermometer requires 2 minutes while most digital thermometers need less than one minute.
Oral temperature
- Do not measure the temperature in a child's mouth if he or she has consumed a hot or cold food or drink in the last 30 minutes.
- Clean the thermometer with cool water and soap.
- Rinse with water.
- Place the tip of the thermometer under the child's tongue towards the back.
- Ask the child to hold the thermometer with his or her lips.
- Keep the lips sealed around the thermometer.
- A glass thermometer requires about 3 minutes while most digital thermometers need less than one minute.
Armpit temperature
- Place the tip of the thermometer in the child's dry armpit.
- Hold the thermometer in place by holding the child's elbow against the chest for 4 to 5 minutes.
Ear temperature
- Ear thermometers are not reliable in infants less than 6 months old.
- If the child has been outside on a cold day, wait 15 minutes before measuring the ear temperature.
- Ear tubes and ear infections do not affect the accuracy of an ear temperature.
- To measure temperature accurately in the ear, the parent must pull the child's outer ear backwards before inserting the thermometer.
- Hold the ear probe in the child's ear for about two seconds.
