Children's Hospital Colorado

Fever - How to Take the Temperature

Urgent or Emergency Care?

If you believe your child needs immediate attention and you have concerns for a life-threatening emergency, call 911. Not sure what counts as urgent and what's an emergency when your child is sick or injured? When it can't wait, know where to take your kids.

Help Me Decide

Barton D. Schmitt, M.D., FAAP

When Does Your Child Have a Fever?

  • Rectal, Forehead or Ear temperature: 100.4° F (38.0° C) or higher
  • Oral (mouth) temperature: 100° F (37.8° C) or higher
  • Under the arm (armpit) temperature: 99° F (37.2° C) or higher
  • Caution: Ear temperatures are not accurate before 6 months of age

Where to Take the Temperature

  • Rectal temps are the most accurate. Forehead temps are the next most accurate. Oral and ear temps are also accurate if done properly. Temps done in the armpit are the least accurate. Armpit temps are useful for screening at any age.
  • Age under 3 months old (90 days old).
    An armpit temp is the safest and is good for screening. If the armpit temp is above 99° F (37.2° C), re-check it. Use a rectal or forehead reading. Reason: If young babies have a fever, they need to see a doctor now. New research shows that forehead temps are accurate under 3 months of age.
  • Age under 4 or 5 years old. Rectal, electronic forehead, or electronic pacifier temps are accurate. An ear thermometer can be used after 6 months old. An armpit temp is good for screening if it is taken right.
  • Age over 4 or 5 years old.
    Safe to take the temp orally (by mouth). Ear and forehead thermometers are also good.

Rectal Temperature: How to Take

  • Age: Birth to 4 years old
  • Have your child lie stomach down on your lap.
  • Put some petroleum jelly on the end of the thermometer and the anus.
  • Slide the thermometer gently into the anus about 1 inch. If your child is less than 6 months old, put it in only about ½ inch. That means until you can no longer see the silver tip.
  • Hold your child still. Leave a digital thermometer in for about 20 seconds. Note: The AAP suggests that older glass thermometers be replaced. They contain mercury. If that's all you have, leave it in for about 2 minutes.
  • Your child has a fever if the rectal temp is above 100.4° F (38° C).

Armpit Temperature: How to Take

  • Age: Any age for screening
  • 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. Do this for 4 or 5 minutes or until your digital thermometer beeps. The tip of the thermometer must stay covered by skin.
  • Your child has a fever if the armpit temp is above 99.0° F (37.2° C). If you have any doubt, take your child's temp by rectum or forehead.

Oral Temperature: How to Take

  • Age: 4 years and older
  • If your child had a cold or hot drink, wait 30 minutes.
  • Put the thermometer under one side of the tongue towards the back. It's important to put the tip in the right place.
  • Have your child hold the thermometer with his lips and fingers. Don't use the teeth to keep in place. Keep the lips sealed. Keep a digital thermometer there for about 30 seconds or until it beeps. (Note: The AAP suggests that older glass thermometers be replaced. They contain mercury. If that's all you have, leave it in for about 3 minutes.)
  • Your child has a fever if the temp is above 100° F (37.8° C).

Digital Pacifier Temperature: How to Take

  • Age: Birth to 1 year
  • Have your child suck on the pacifier until you hear a beep.
  • This takes 3 to 4 minutes.
  • Your child has a fever if the pacifier temp is above 100° F (37.8° C).

Ear Temperature: How to Take

  • Age: 6 months and older (not accurate before 6 months)
  • This thermometer reads the heat waves coming off the eardrum.
  • A correct temp depends on pulling the ear backward. Pull back and up if over 1 year old.
  • Then aim the tip of the ear probe between the opposite eye and ear.
  • Parents like this thermometer because it takes less than 2 seconds. It also does not need the child to cooperate. It does not cause any discomfort.
  • Caution. Being outdoors on a cold day will cause a low reading. Your child needs to be inside for 15 minutes before taking the temp. Earwax, ear infections and ear tubes do not keep from getting correct readings.

Forehead (Temporal Artery) Temperature: How to Take

  • Age: Any age
  • This thermometer reads the heat waves coming off the temporal artery. This blood vessel runs across the forehead just below the skin.
  • Place the sensor head at the center of the forehead.
  • Slowly slide the thermometer across the forehead toward the top of the ear. Keep it in contact with the skin.
  • Stop when you reach the hairline.
  • Read your child's temp on the display screen.
  • Used in more doctor's offices than any other thermometer.
  • Parents like this thermometer because it takes less than 2 seconds. It also does not need the child to cooperate. It does not cause any discomfort.
  • Caution: Forehead temperatures must be digital. Forehead strips are not accurate.

Disclaimer

The information contained in these topics is not intended nor implied to be a substitute for professional medical advice, it is provided for educational purposes only. You assume full responsibility for how you choose to use this information.

Always seek the advice of your physician or other qualified healthcare provider before starting any new treatment or discontinuing an existing treatment. Talk with your healthcare provider about any questions you may have regarding a medical condition. Nothing contained in these topics is intended to be used for medical diagnosis or treatment.

  • Not a Substitute - The information and materials in Pediatric HouseCalls Symptom Checker should not be used as a substitute for the care and knowledge that your physician can provide to you.
  • Supplement - The information and materials presented here in Pediatric HouseCalls Symptom Checker are meant to supplement the information that you obtain from your physician. If there is a disagreement between the information presented herein and what your physician has told you -- it is more likely that your physician is correct. He or she has the benefit of knowing your child's medical problems.
  • Limitations - You should recognize that the information and materials presented here in Pediatric HouseCalls Symptom Checker have the following limitations, in comparison to being examined by your own physician:
    • You can have a conversation with your child's doctor.
    • Your child's doctor can perform a physical examination and any necessary tests.
    • Your child could have an underlying medical problem that requires a physician to detect.
    • If your child is taking medications, they could influence how he experiences various symptoms.

If you think that your child is having a medical emergency, call 911 or the number for the local emergency ambulance service NOW!

And when in doubt, call your child's doctor NOW or go to the closest emergency department.

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