Which thermometer for which patient?

• Rectal measurements, either with an electronic or glass thermometer, are quite accurate and generally preferred for children less than 3 months old and those who can't yet hold a thermometer in the mouth.

• Oral thermometers.  Electronic thermometers are preferred over glass for your children because they work faster and young children are not able to keep the glass thermometer under the tongue with the mouth closed. Glass thermometers should be acceptable for most older children.

• Tympanic (ear) thermometers measure the magnitude of infrared radiation from the tympanic membrane and the surrounding ear canal. They are quick, easy to use, and well-tolerated for screening the temperature of most children; however, they are not always accurate. If the reading does not agree with what you think the child's temperature might be, take the temperature by another method.

• Axillary (armpit) readings may not always be accurate and should only be considered an estimate of the temperature.

• Plastic strips that are placed on the forehead are popular with parents, but aren't recommended because they usually give falsely elevated readings.

How to take a rectal temperature:

Lubricate the end of the thermometer with petroleum jelly. Then:

• Have your child lie stomach-down on your lap.

• Lubricate the opening of the anus with petroleum jelly.

• Carefully insert the thermometer about 1 inch into the rectum. Never force it.

• Hold your child still, press his buttocks together to hold the thermometer in place.

• Leave the thermometer in the rectum for two minutes with a glass thermometer, or approximately 30 seconds (until you hear the "beep") with a digital thermometer.