Fever - How to Take the Temperature

When Does Your Child Have a Fever?

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 reading. Reason: If young babies have a fever, they need to see a doctor now. New research shows that forehead temps may also be accurate under 3 months of age.
Age 3 months to 4 years old. Rectal or forehead 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 4 years and older. Safe to take the temp orally (by mouth). Ear and forehead thermometers are also good.
Digital (electronic) thermometers are widely available and inexpensive. They can be used for rectal, armpit and oral temps. Most of them give an accurate temp in 10 seconds or less. They have replaced glass thermometers which contained mercury (AAP).

Rectal Temperatures - How to Take:

Age: Birth to 4 years old
Have your child lie stomach down on your lap. Another way is on the back with the legs pulled up to the chest.
Put some petroleum jelly on the end of the thermometer and the anus.
Slide the thermometer gently into the anus no more than 1 inch (2.5 cm). If your child is less than 6 months old, put it in no more than 1/2 inch (12 mm). That means until you can no longer see the silver tip.
Be gentle. There should not be any resistance. If there is, stop.
Hold your child still. Leave a digital thermometer in until it beeps (about 10 seconds).
Your child has a fever if the rectal temp is 100.4° F (38° C) or higher.

Armpit Temperatures - 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 until it beeps (about 10 seconds). The tip of the thermometer must stay covered by skin.
Your child has a fever if the armpit temp is 99.0° F (37.2° C) or higher. If you have any doubt, take your child's temp by rectum or forehead.

Oral Temperatures - 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 over the thermometer until it beeps (about 10 seconds).
Your child has a fever if the temp is 100° F (37.8° C) or higher.

Digital Pacifier Temperature - How to Take:

Age: Birth to 1 year. Only good for screening. Requires the baby to suck on it, which is not always possible.
Have your child suck on the pacifier until it beeps (about 10 seconds).
Your child has a fever if the pacifier temp is 100° F (37.8° C) or higher.

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.
Note: Some newer forehead thermometers don't need to slide across the forehead. Follow the box directions on how to take the temp.
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.