How to Take a Baby’s Temperature

How to Take a Baby's Temperature

Learn how to take your baby’s temperature, the right kind of thermometer to use and when a baby’s fever warrants a call to the doctor.

Your baby seems fretful and warm to the touch. Does she have a fever? The only sure way to find out is to take her temperature.

It may be a little scary the first time you take your baby’s temperature, but you can do it. The step-by-step directions below will show you how. Knowing your baby’s temperature will help you decide if you need to call a doctor.

1. Use the right thermometer

To check your baby’s temperature, use a digital thermometer. They are inexpensive, reliable and easy to read. For babies, they are used in the rectum (rectal) or under the arm (axillary). Rectal temperatures are the most accurate.

Other types of thermometers, including eardrum (tympanic) thermometers, are not advised because they are not very accurate.

Do not use old-style glass thermometers. They contain mercury, which is toxic and can be dangerous if the thermometer breaks. If you still have one, get rid of it but don’t throw it in the trash. Ask your doctor or local health department how to dispose of it. Many cities and counties have hazardous waste disposal programs that will take mercury thermometers.

2. Check your baby’s temperature

Use a rectal thermometer to take your baby’s temperature. To take a rectal temperature:

  • Clean the tip of the thermometer with rubbing alcohol or soap and water. Rinse with cool water.
  • Lubricate the thermometer tip with petroleum jelly.
  • Lay your baby belly-down across your lap or on a changing table. Hold the baby by placing one hand on the small of his or her back.
  • Turn the thermometer on and gently slide it about one-half to one inch into your baby’s rectum. Don’t force it or push it in too far.
  • Hold the thermometer while it is in your baby’s rectum to avoid injury. Keep it there for about one minute or until the thermometer beeps.
  • Pull the thermometer out and read it.

You can take an underarm reading in a baby older than 3 months if you can’t get a rectal reading. To take an underarm (axillary) temperature:

  • Turn the thermometer on and place the tip of the thermometer in the baby’s armpit.
  • Hold your baby’s arm tightly against his or her side for about one minute or until the thermometer beeps.

3. When to call a doctor

Normal body temperature ranges from 97 degrees F to 99 degrees F during the day. A temperature of 100.4 degrees F or higher signals a fever.

In an otherwise healthy baby, a fever usually is not serious and may not need to be treated. However, a fever can be a sign of a dangerous infection. Fever in a young infant is always a cause for concern.

Call 9-1-1 for any child with fever who is:

  • Having trouble breathing
  • Extremely ill with a rash or unusual bruising
  • Lethargic, passing out, having seizures or confused

Take your child to the emergency room if your child:

  • Is 3 months of age or younger and has a fever of 100.4 degrees F or higher.
  • Has a fever of 105 degrees or higher.
  • Has a fever with a stiff neck or seems very ill. (These may be signs of meningitis, a serious infection of the brain and spinal cord.)
  • Had a seizure.
  • Looks very dehydrated or extremely ill.
  • Has violent shaking chills.

You should call your doctor if your child has a fever and:

  • Appears dehydrated
  • Has a chronic illness or weak immune system
  • It lasts for 72 hours or longer
  • It went away for at least 24 hours without fever-reducing medicines but then it came back
  • You are concerned that there may be a serious problem
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