FAQ: How to take a Temperature



Temperature Basics

What is a true fever?

A fever is defined as a temperature equal to and greater than 100.4° Farenheit or 38° Celcius.

What is the “normal” body temperature?

The mean normal temperature is generally considered to be 98.6 ° F or 37° C.   Normal body temperature can change with age, the time of day, level of activity as well as other factors.  For example, infants have higher average “normal” temperatures, with an average of 99.5° F or 37.5° C as they have higher metabolic activity.  Temperature also varies with time of day, with a morning low and a late afternoon/early evening peak.  

Where is the best place to take a temperature?

  • The most common sites to take a temperature are the rectum, mouth, and axilla (armpit), eardrum or forehead.  The best method depends on the age of your child and the method that easiest for the caregiver and your child.
  • Rectal temperatures are the most accurate (the “gold standard”).  Oral or eardrum temperatures are accurate if done properly, and a good choice when children are old enough to cooperate.  Axillary (armpit) and forehead temperatures are the least accurate, but can screen for fevers.
  • If a child 3 months old or younger has a fever (100.4°F and greater), they need to be evaluated by a doctor immediately.  If the axillary temperature is over 99.0°F, check it again by taking a rectal temperature to get the most accurate measurement.  

How do you take a rectal temperature?

  • Have your child lie stomach down on your lap
  • Apply petroleum jelly to the end of the thermometer and to the opening of the anus
  • Gently insert thermometer into the rectum  about ¼ inch. Never force it past any resistance.

How do you take an axillary temperature?

  • Place the tip of the thermometer in a dry armpit
  • Close the armpit by holding the elbow against the chest 
  • If you are uncertain about the result, check it with a rectal temperature

How do you take an oral temperature?

  • Be sure your child has not had a recent cold or hot drink 
  • Place the tip of the thermometer under the tongue and toward the back
  • Have your child hold it in place keeping the mouth closed. If your child is “mouth breathing” this will report a lower temperature.
  • Oral temperatures are hard to do accurately if your child has a lot of nasal congestion.
  • If there are any questions, please do not hesitate to ask!