When Does Your Baby Have a Fever??
- Average body temperature is around 98.6° F (37.0° C)
- A fever is an elevated body temperature with these readings:
- Rectal, Forehead or Ear temperature: 100.4° F (38.0° 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. 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 1 year 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.
- Digital (electronic) thermometers are easily found in stores. They do not cost very much. They can be used for rectal and armpit temps. Most of them give an accurate temp in 10 seconds or less. The AAP suggests you replace any glass thermometer in the house with one of these products.
Rectal Temperature: How to Take
- Age: Birth to 1 year 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. If your child is less than 6 months old, put it in no more than ½ inch. 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 above 100.4° F (38° C).
- Warning: do not take rectal temperatures in young children with leukemia or other cancers. Also avoid in other children with weak immune systems such as organ transplant, HIV or sickle cell disease.
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 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 above 99.0° F (37.2° C). If you have any doubt, take your child's temp by rectum or forehead.
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 Touch 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.
- This is the one most used in hospitals and doctors’ offices.
- Place the sensor head at the center of the forehead touching the skin.
- 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.
Forehead No-Touch Temperature: How to Take
- Age: any age
- Aim the thermometer at the center of the forehead.
- Stay less than 1 inch (2.5 cm) away. Do not touch the forehead.
- Do not move the thermometer.
- Press the measurement button.
Copyright 2000-2023 Schmitt Pediatric Guidelines LLC.
Barton Schmitt MD, FAAP