Ask the experts: Fever facts

How will I know if my baby has a fever? The very thought terrifies me!
In general, a person (child or adult) is said to have a fever when her temperature is 100.4°F or higher. Fever in itself is not an illness, rather it’s the body’s way of telling us that it is fighting an infection. (That infection may be a cold, flu, strep throat or another condition.) In fact, fever is our friend because it actually helps fight infection. The increased temperature interferes with the growth and reproduction of certain viruses and bacteria, and it also enhances our immune system.
With a fever, your baby will feel warm to the touch. If that’s the case, you can take your baby’s temperature. For infants under 3 months, you’ll want to take it rectally with a digital thermometer. For babies over 3 months, choose the method you’re most comfortable with. Options include tympanic (ear), temporal artery (forehead) and oral (mouth) thermometers among others. The oral thermometer can also be used to take an axillary temperature (under the arm). Beyond the first three months, it doesn’t really matter which method you choose as long as you are comfortable and can get an accurate read.
If your child is under 3 months old, be sure to call your doctor anytime she has a fever. For older children, no matter what the temperature, call your doctor if your child looks sick, is having difficulty breathing, cannot keep hydrated with fluids, or has a fever that lasts more than a few days.
—Alanna Levine, MD, pediatrician at Orangetown Pediatric Associates in Tappan, New York