thermometer basics

8/4/2019 Thermometer Basics

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Thermometer basics: Taking your child's temperature

Thermometer choices got you baffled? Understand the different thermometeroptions and when to seek medical help for a fever.

By Mayo Clinic staffIf your child feels warm or seems under the weather, it's probably time to take his or her temperature.

Sounds simple enough but if you're new to it, you may have questions. Which type of thermometer is

best? Are thermometer guidelines different for babies and older children? Here's what you need to know

to take your child's temperature.Know your thermometer options

A glass mercury thermometer was once a staple in most medicine cabinets. Today, digital thermometers

are recommended instead of mercury thermometers, which can break and allow mercury to vaporize and

be inhaled.

Regular digital thermometers, which use electronic heat sensors to record body temperature, can be used

in the mouth, armpit or rectum. Digital ear thermometers, also called tympanic thermometers, use an

infrared ray to measure the temperature inside the ear canal. Other options include a digital pacifier

thermometer and temporal artery thermometer which uses an infrared scanner to measure the

temperature of the temporal artery in the forehead.

If you want to get a single thermometer for the entire family, a regular digital thermometer is probably

best. However, if you plan to use the digital thermometer to take a rectal temperature, get two digital

thermometers and label one for oral use and one for rectal use. Don't use the same thermometer in both

places.

Accuracy varies

The most accurate way to take a child's temperature is to use a digital thermometer rectally or orally.

Rectal temperatures provide the best readings for infants. Ear thermometers are another option for

babies and older children. However, earwax or a small, curved ear canal can interfere with the accuracy

of a temperature taken with an ear thermometer. Armpit temperatures and temperatures measured with a

pacifier thermometer are considered the least accurate methods. The reliability of temporal artery

thermometers hasn't yet been verified.

Whatever the method, make sure you carefully read the instructions that came with your thermometer.

After each use, clean the tip of the thermometer with rubbing alcohol or soap and lukewarm water. For
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safety and to make sure the thermometer stays in place never leave your child unattended while

you're taking his or her temperature.

Age matters, too

The best type of thermometer or the best place to insert the thermometer, in some cases depends

on your child's age.

Birth to 3 months. For newborns, use a regular digital thermometer to take a rectal temperature. Turn on

the digital thermometer and lubricate the tip of the thermometer with petroleum jelly. Lay your baby on his

or her back, lift your baby's thighs, and insert the lubricated thermometer 1/2 to 1 inch (1.3 to 2.5

centimeters) into your baby's rectum. Stop if you feel any resistance. Hold the thermometer in place for

about a minute or until the thermometer signals that it's done. Remove the thermometer and read the

number.

3 months to 4 years. For older infants and toddlers, you can use a digital ear thermometer, a digital

pacifier thermometer or a temporal artery thermometer. Carefully follow the instructions that came with

your thermometer. You can also use a regular digital thermometer to take a rectal temperature or an

armpit temperature. To take an armpit temperature, first turn on the digital thermometer. When you place

the thermometer under your child's armpit, make sure it touches skin not clothing. Hold the

thermometer tightly in place for about a minute or until the thermometer signals that it's done. Remove the

thermometer and read the number.

4 years and older. By age 4, most kids can hold a digital thermometer under the tongue for the short

time it takes to get a temperature reading. Turn on the digital thermometer. Place the tip of the

thermometer under your child's tongue and ask your child to keep his or her lips closed. Remove the

thermometer when it signals that it's done and read the number. If your child has been eating or drinking,

wait at least 15 minutes to take his or her temperature by mouth. If your child is too congested to breathe

through his or her nose, you may need to take an armpit or rectal temperature or use a digital ear

thermometer.

When to see a doctor

A fever is a common sign of illness, but that's not necessarily a bad thing. In fact, fevers seem to play a

key role in fighting infections. If your child is older than age 1 and is drinking plenty of fluids, sleeping well

and continuing to play, there's usually no reason to treat a fever.


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If you want to give your child medication to treat a fever, stick to acetaminophen (Tylenol, others) until

age 6 months. If your child is age 6 months or older, ibuprofen (Advil, Motrin, others) is OK, too. Read the

label carefully for proper dosage. Don't use aspirin to treat a fever in anyone age 18 years or younger.

In general, contact your child's doctor if your child:

Is younger than age 3 months and has a rectal temperature of 100.4 F (38 C) or higher

Is older than age 3 months, has a temperature up to 102 F (38.9 C) and seems unusually irritable,

lethargic or uncomfortable

Is older than age 3 months and has a temperature of 102 F (38.9 C) or higher that doesn't respond to

over-the-counter medication or lasts longer than one day

When reporting a temperature to your child's doctor, give the actual reading and state how the

temperature was taken. Don't add or subtract numbers from the reading depending on where the

thermometer was placed.

PARENT CARE: FEVER, HOW TO TAKE THETEMPERATURE

Definition of Fever

Rectal temperature above 100.4F (38.0C).

Oral temperature above 99.5F (37.5C).

Axillary (armpit) temperature above 99.0F (37.2C).

Pacifier temperature above 100F (37.8C). New digital electronic ones are accurate.

Ear (tympanic) temperature above 100.4F (if in rectal mode) or above 99.5F (if in oral mode). (Note: Not

reliable for less than 6 months old.) Temporal artery (TA) temperature above 100.4 F (38.0 C) (Note: more reliable than tympanic thermometers,

but not to be used for children under 6 months old)

Where to Take the Temperature

Temperatures measured rectally are the most accurate. Temperatures measured orally, by electronicpacifier, or by ear canal are also accurate if done properly. Temperatures measured in the armpit are theleast accurate, but they are better than no measurement.


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Age less than 3 months old (90 days old):An armpit temperature is preferred for reasons of safety and is adequate for screening. If the armpittemperature is above 99F (37.2C), check it with a rectal temperature. The reason you need to take arectal temperature for young infants is that if they have a true fever, they need to be evaluated immediately.

Age less than 4 or 5 years old:A rectal or electronic pacifier temperature is preferred. An axillary (armpit) temperature is adequate forscreening if it is taken correctly. An ear thermometer can be used after 6 months old.

Age older than 4 or 5 years old:Take the temperature orally (by mouth) or by ear thermometer.

How to Take Rectal Temperatures

Have your child lie stomach down on your lap.

Put some petroleum jelly on the end of the thermometer and on the opening of the anus.

Slide the thermometer gently into the opening of the anus for about 1-inch. If your child is less than 6months old, put it in only about to inch (inserting until the silver tip disappears is about inch).

Hold your child still and leave the thermometer in 2 minutes with a glass thermometer (about 20 secondswith a digital electronic thermometer).

Your child has a fever if the rectal temperature is above 100.4F (38C).

How to Take Armpit Temperatures

Put the tip of the thermometer in an armpit. Make sure the armpit is dry.

Close the armpit by holding the elbow against the chest for 4 or 5 minutes.

Your child has a fever if the armpit temperature is above 99.0F (37.2C). If you have any doubt, take yourchild's temperature by rectum.

How to Take Oral Temperatures

Be sure your child has not had a cold or hot drink in the last 30 minutes.

Put the tip of the thermometer under one side of the tongue and toward the back. It's important to put it in

the right place. Have your child hold the thermometer in place with his lips and fingers (not teeth) for 3 minutes with a glass

thermometer (about 30 seconds with a digital electronic thermometer). Keep the lips sealed.

Your child has a fever if the temperature is above 99.5F (37.5C)

How to Take a Digital Electronic Pacifier Temperature

Have your child suck on the pacifier until it reaches a steady state, and you hear a beep.

This usually takes 3 to 4 minutes.

Your child has a fever if the pacifier temperature is above 100F (37.8C)

How to Take an Ear Temperature

This thermometer reads the infrared heat waves released by the eardrum.

An accurate temperature depends on pulling the ear backward to straighten the ear canal (back and up ifover 1 year old).

Then aim the tip of the ear probe midway between the opposite eye and earlobe.

The biggest advantage of this thermometer is that it measures temperatures in less than 2 seconds. It alsodoes not require cooperation by the child and does not cause any discomfort.

Limitation: if your child has been outdoors on a cold day, he needs to be inside for 15 minutes before takingthe temperature. Earwax, ear infections and ear tubes, however, do not interfere with accurate readings.


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