Fever in an infant can be scary for a new parent or even for an experienced one. Be prepared by reading up now on the answers to the questions you’ll have should the situation arise.

What’s the Right Way to Take a Baby’s Temperature?

If you don’t have a digital multi-use thermometer, put one on your shopping list right now. Reliable, inexpensive and easy to use, it’s recommended by the American Academy of Pediatrics (AAP) as the best tool for taking the temperature of infants and children. While they might seem easier still, thermometers that are designed for use in the ear or on the forehead aren’t as precise because they can be affected by external temperatures.

For infants and toddlers under 2, using the digital thermometer rectally gives the most accurate reading. After that age, you can use a digital thermometer in the armpit or orally if the child will hold it under his or her tongue for the minute or so it takes to get a read-out.

What’s a Baby’s Normal Temperature?

A baby’s normal temperature can range from about 97 degrees Fahrenheit up to 100.3 degrees Fahrenheit. Most doctors consider 100.4 or higher a fever.

What Causes a Fever?

A fever is a symptom rather than an illness itself. While a fever more often can indicate that a baby has a cold or other viral infection, it can less commonly be caused by a urinary tract or ear infection, or more serious bacterial infection.

On the other hand, there are also some innocent reasons for a baby to run a fever, including reaction to a vaccination, simply being overheated from being swaddled or dressed too warmly, or spending too much time outside on a hot day. Older babies may also run a higher temperature when they’re teething.

What Can I do to Reduce a Fever at Home?

If your baby is over 3 months old and is alert and acting normally, his or her temperature hasn’t exceeded 102 degrees Fahrenheit, and you suspect one of the innocent causes of fever, you can try one of these methods of bringing down the thermometer reading:

• Cold compress: wet a washcloth in cool water, wring it out, and place it on your baby’s head.
• Fluids: giving your baby plenty of fluids will prevent dehydration and aid his or her body in cooling itself. Symptoms of dehydration include a dry mouth, no tears with crying, or fewer wet diapers.
• Sponge bath: a lukewarm sponge bath can bring a fever down. A cold bath, though, can cause shivers that actually raise your baby’s temperature.

What about Medication?

Do not give fever-reducing medication of any kind (like children’s Tylenol or ibuprofen as in Advil or Motrin) to a baby or child of any age without first checking with a doctor. And never give babies aspirin for a fever because of the risk for a rare but potentially dangerous condition called Reye’s syndrome.

When Should I Call the Doctor or Go to an ER or Urgent Care?

Treating a high fever requires professional medical advice and attention. Here are the guidelines to follow:

• For babies younger than 3 months old: if your baby has a rectal temperature of 100.4 degrees Fahrenheit or higher, it is considered an emergency. See your pediatrician, or go to an urgent care center, or an emergency room immediately.
• For babies 3-6 months old: if your baby’s fever is 102 degrees Fahrenheit, or if his or her fever lasts longer than 24 hours, call your pediatrician or visit an urgent care center.
• For babies 6 months to 2 years old: if your baby’s fever is between 102 and 102.9 degrees Fahrenheit, watch his or her behavior, and call your pediatrician or visit an urgent care center if the fever lasts more than two days.
• For toddlers and children older than 2 years old: if your child’s fever is above 103 degrees Fahrenheit, or if his or her fever lasts longer than three days, call your pediatrician or visit an urgent care center.

If you’re concerned about troubling symptoms even if not accompanied by a fever, don’t hesitate to contact your pediatrician for advice.