How to Take Your Child’s Temperature
If your child is ill or feels warm to touch, it is a good idea to take their temperature to check for a fever—especially before they go to school, daycare, sports, or other activities. But with all of the different methods and types of thermometers available, it may be difficult to know which is best to use and when. Use the following guidelines to understand how to take your child’s temperature safely and accurately as well as when to use each method, categorized by age.
What Temperature Is Considered a Fever?
Rectal Temperature—100.4℉ (38℃) and higher
Temporal (Forehead) Temperature—100.4℉ (38℃) and higher
Oral Temperature—100℉ (37.8℃) and higher
Tympanic (Ear) Temperature—100.4℉ (38℃) and higher
Axillary (Armpit) Temperature—99℉ (37.2℃) and higher
What Are the Different Types of Thermometers?
The American Academy of Pediatrics (AAP) currently recommends digital thermometers as they are the quickest and most accurate. Glass mercury thermometers are no longer recommended as they are dangerous: These thermometers can break and release mercury fumes that are toxic if inhaled (if exposure or suspected exposure occurs, call your local Poison Control by dialing 1-800-222-1222). It is currently recommended to remove any mercury-containing thermometers from your home (see how to do this safely here). Plastic strip thermometers, pacifier thermometers, and smartphone temperature apps are also not recommended as they are less accurate.
There are three types of recommended digital thermometers available:
Regular Digital (Multi-Use) Thermometer
Measures temperature using electronic heat sensors located on the tip of the thermometer.
Can be used to measure temperature in the rectum (rectal), in the mouth (oral), or under the armpit (axillary). Always designate and label the thermometer as “oral” or “rectal.” Be sure to have two that are properly labeled if both methods are sometimes used so as not to mix them up.
Rectal use—Children 3 years old and under. The most accurate reading especially for infants under 3 months old.
Oral use—Children 4 years old and over and can cooperate. Accurate if done properly.
Axillary use—All ages. The least accurate of all methods.
Digital Forehead (Temporal Artery) Thermometers
Uses infrared sensors to measure heat waves coming off the temporal artery (blood vessel just below the skin in the forehead).
All ages. The second most accurate reading after rectal temperature.
Different manufacturers may have different instructions for use depending on if it is a non-contact (no touch) model or not.
Non-contact models may reduce the risk of transmitting germs.
Digital Ear (Tympanic) Thermometers
Uses infrared sensors to measure heat waves in the ear canal.
Children 6 months old and over. Accurate if done properly. Not reliable for younger babies as their ear canals may be too narrow.
Best Ways to Measure Temperature by Age
Determining which method is best to measure your child’s temperature depends on your child’s age and ability to cooperate:
Birth–3 months old—Rectal is best.
3–6 months old—Rectal is best. Temporal artery (forehead, second-most accurate) and axillary (armpit, least accurate) may also be used.
6 months–3 years old—Rectal is best. Temporal artery (forehead, second-most accurate), tympanic (ear, accurate if done properly), and axillary (armpit, least accurate) may also be used.
4 years old and over—Oral is best if they can properly hold thermometer under the tongue. If not, rectal (most accurate), temporal artery (forehead, second-most accurate), tympanic (ear, accurate if done properly), and axillary (armpit, least accurate) may also be used.
How to Take a Rectal Temperature
Wash the tip of the thermometer with soap and water or alcohol swab
Place a small amount of lubricant (like petroleum jelly) on the tip of the digital thermometer
Place your child either:
Belly-down: Across your lap or on a firm, flat surface with one hand on lower back OR
Face-up on their back with legs bent toward the chest with one hand on back of thighs
Turn on the thermometer with other hand
Gently insert lubricated thermometer ½ inch (for babies less than 6 months old) to 1 inch (or about 1.25cm to 2.5cm) into the anus
STOP if you feel any resistance
Hold the child still and thermometer in place until it beeps
Gently remove and check digital reading
A fever is a rectal reading of 100.4℉ (38℃) and higher
How to Take a Temporal Artery (Forehead) Temperature
Turn on the thermometer
Gently sweep thermometer across child’s forehead (use manufacturer’s instructions to determine how and where to slide or aim sensor on forehead for the most accurate reading)
Check temperature reading on the display screen
A fever is a temporal reading of 100.4℉ (38℃) and higher
How to Take an Oral Temperature
Wait 30 minutes after any hot or cold food or beverages as this may cause an inaccurate reading
Turn on the digital thermometer
Place the tip of thermometer under the tongue and have your child close their lips around it
Breathe normally through the nose
Do not bite down on the thermometer, talk, or open mouth until the reading is complete
Hold in place until thermometer beeps
Gently remove and check digital reading
A fever is an oral reading of 100℉ (37.8℃) and higher
How to Take a Tympanic (Ear) Temperature
Turn on the thermometer
For children over 1 year old:
Pull and hold the ear back and up
Aim the tip of the ear probe towards the area between the opposite ear and eye
Follow manufacturer’s instructions to determine the proper distance to insert the thermometer into the ear canal
Hold in place until thermometer beeps
Gently remove and check digital reading
A fever is a tympanic reading of 100.4℉ (38℃) and higher
How to Take an Axillary (Armpit) Temperature
Remove child’s shirt
Turn on the thermometer
Place thermometer tip under armpit (touching skin only, NOT clothing)
Place child’s arm down and across the chest, holding thermometer in place
Hold in place until thermometer beeps
Gently remove and check digital reading
A fever is an axillary reading of 99℉ (37.2℃) and higher
Tips for an Accurate Temperature Reading
Environmental factors may cause inaccurate readings. Wait 15 minutes after being outside on a cold day before taking a temperature to avoid an inaccurate low reading. Similarly, wait 20-30 minute after a bath or being under blankets, in multiple layers, or swaddled (if an infant) before taking a temperature to avoid an inaccurate high or low reading. When taking an oral temperature, be sure to avoid hot or cold food or drink for 30 minutes prior to avoid an inaccurate reading.
Key Points to Remember
Deciding which method is best to take your child’s temperature depends on your child’s age and ability to cooperate. Rectal temperatures are typically best and provide the most accurate readings for babies and children 3 years old and younger while oral temperatures are typically best and most accurate for children 4 years old and older (who can properly hold the thermometer in place for the required measurement time). Other methods available that are quick and easy to use may not provide the most accurate readings. Remember, while a fever is an important sign of illness, how your child over 3 months old looks and acts is key. Always play it safe and call your child’s pediatrician with any questions or concerns regarding your child’s fever or illness.
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