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Taking Your Child's Temperature

Reviewed by: Wayne Ho, MD

As any parent knows, taking a squirming child's temperature can be a challenge. But checking for a fever is one of the most important ways you can assess illness or infection in your child. With some basic guidelines about the types of thermometers and the various methods for taking your child's temperature, you'll soon be doing it like a pro.

Once considered a must-have for every medicine cabinet, the inexpensive glass mercury thermometer was the most common type of thermometer for home use. However, the American Academy of Pediatrics (AAP) now advises parents to stop using glass thermometers at home because of concerns about possible exposure to mercury, an environmental toxin. If the thermometer breaks, the mercury could leak out. But do not simply throw away your mercury thermometer in the trash where it can leach into the environment or endanger anyone handling the trash. Talk to your child's doctor or your local health department about how and where to dispose of your mercury thermometer.

Although the amount of mercury inside a glass thermometer is actually very small, the AAP's official policy is that other types of thermometers are safer. Some of the alternatives, however, are more reliable than others:

Electronic probe thermometers can be used orally (in the mouth), rectally (in the bottom), or in an axillary position (in the armpit). They usually have a plastic, flexible probe with a temperature sensor at the tip and an easy-to-read digital display on the opposite end. They tend to be quicker, easier to use, and easier to read than glass mercury thermometers. Electronic probe thermometers come in many sizes and shapes and range in price. Be sure to read the package instructions to know what method or methods (axillary, rectal, or oral) the thermometer is designed for. When used correctly, electronic thermometers tend to give very accurate readings.

               thermometerElectronic ear thermometers can quickly and easily measure the tympanic temperature - the temperature inside the ear canal. However, ear thermometers aren't as accurate as probe thermometers - they tend to give falsely low readings, especially in younger kids. The AAP advises against using electronic ear thermometers for infants younger than 3 months.

Plastic strip thermometers (small plastic strips that you press against your child's forehead) may be able to tell you whether your child has a fever, but aren't reliable for taking an exact measurement. For exact readings, use a digital thermometer.

Choosing a Method
Children younger than 4 or 5 years old are usually too young to cooperate with oral temperature readings, so parents use the rectal or axillary method with an electronic probe thermometer. Although rectal temperatures give the most accurate reading, it may be better for parents of infants to opt for the axillary method because taking a temperature rectally can be difficult for the parent and uncomfortable for the baby (and even dangerous, if the parent pushes the thermometer in too far). The axillary method is also useful in older children who are so upset or uncomfortable from an illness that they can't cooperate with taking a rectal or oral temperature.

You usually can take the temperature of an older child orally if he or she will cooperate. However, kids who have frequent coughs or are breathing through their mouths because of a stuffy nose might not be able to keep their mouths closed long enough for an accurate oral reading. If this is the case with your child, it would be better to use the axillary or tympanic method.

No matter what method or type of thermometer you choose, children should never be left unattended while you're taking their temperature. You should also never take a child's temperature right after a bath, because that can affect the temperature reading.

Using an Electronic Probe Thermometer
When using an electronic probe thermometer - which gives the most accurate reading - be sure to read the directions beforehand, as each model has a different beep or series of beeps to tell you that it's finished reading. Once you turn it on and make sure that the screen is clear of any old readings, you can put on a plastic sleeve or cover (if your model uses them) and place it according to the instructions. Once it's done and you've taken the reading, you should discard the plastic sleeve and clean the thermometer according to the manufacturer's instructions before returning it to its case.

Taking a Rectal Temperature
Before becoming parents, most people cringe at the thought of taking a rectal temperature. But don't worry - it's a simple process:

  1. Lubricate the tip of a clean electronic probe thermometer with a lubricating jelly (such as petroleum jelly) recommended by your child's doctor.
  2. Place your child across your lap, supporting the head, or lay the child down on a firm, flat surface such as a changing table.
  3. Press the palm of one hand firmly against your child's lower back to prevent wiggling.
  4. Using your other hand, insert the lubricated thermometer through the anal opening, about half an inch to 1 inch (about 13 to 25 millimeters) inside the rectum. Stop at less than half an inch (13 millimeters) if you feel resistance.
  5. Steady the thermometer between your second and third fingers as you cup your hand against your child's bottom. Soothe your child and speak quietly as you hold the thermometer in place.
  6. Wait until you hear the signal that the thermometer is finished. Read and record the number on the screen, noting the time of day that you took the reading.

Taking an Oral Temperature
If your child has just finished eating or drinking, you should wait 20 to 30 minutes before taking an oral temperature. The process is easy in the older, cooperative child:

  1. Make sure your child's mouth is clear of candy, gum, or food.
  2. Place the tip of the electronic probe thermometer under your child's tongue and have your child close his or her mouth and lips around it. Remind your child not to bite the thermometer or talk with it in the mouth. Your child should relax and breathe normally through the nose.
  3. Wait until you hear the signal indicating that the thermometer is finished. Read and record the number on the screen, noting the time of day that you took the reading.

Taking an Axillary (Armpit) Temperature
This is a convenient way to take your child's temperature, but it isn't as accurate as the oral or rectal temperature:

  1. Remove your child's shirt and undershirt (the thermometer should touch skin only, not clothing).
  2. Lift your child's arm and place the electronic probe thermometer in your child's armpit. Lower the arm and fold it comfortably across the chest to hold the thermometer in place.
  3. Wait until you hear the appropriate number of beeps or other signal that the temperature is ready to be read. Read and record the number on the screen, noting the time of day that you take the reading.

Deciding the Next Steps
If your child has a fever, you may need to call the doctor. Chances are that the problem is routine and your child's doctor can help you clear it up. By successfully taking and recording your child's temperature, you've gathered some of the information that you and the doctor need to help your child feel better.

Reviewed by: Wayne Ho, MD
Date reviewed: January 2004