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  • Writer's pictureBaby Whisperers

Ultimate Fever Guide for Babies and Children

Updated: Jan 19, 2021


Did we scare you?

Just that word can strike fear in many parents’ hearts. How high of a temperature is considered a fever? When should I treat the fever? When should I call the doctor? What about newborns? We are here for you!

Before proceeding we would also like to point out that none of the below information should be used in substitute of medical advice from your pediatrician. Every child and diagnosis is different. When in doubt, always consult your pediatrician, especially if your child has existing health conditions or complications.


It is important to remember that a fever is a natural reaction in the body. Fevers are intended to help create an environment within our bodies that viruses and bacteria cannot grow in, therefore helping us kill off these bugs. If your child has a fever- don’t panic! This means their little body is responding appropriately.

What is considered a fever?

Although this can differ from child to child, the general rule is that a fever is:

  • Greater than 100.4 F (38 C) in babies under 3 months.

  • Greater than 102 F (38.9 C) in children 3 months and up.

Both the CDC and the Mayo Clinic have stated the above numbers as the definition of a fever. However, we would like to point out that your pediatrician may say something different. Each hospital and each doctor may differ. When in doubt, call your pediatrician.

What types of thermometers are most accurate?

Temperatures measured rectally are the most accurate. This is what the nurses will most likely do when you take your baby to the doctor’s office. If you have been trained and are comfortable taking rectal temperatures at home on your baby, make sure you have a separate thermometer used only for rectal temps.

Second most accurate is taking a temperature orally, followed by axillary (under the armpit) as a close second. Axillary is a good next step if you have a baby, who of course cannot tolerate having a temperature taken orally. Some research has concluded that both of these temperature routes consistently average about 1 degree Fahrenheit lower than rectal temps, so keep this in mind when taking temperatures these routes.

Least accurate are the temporal (forehead) and tympanic (ear) thermometers. These routes are good for getting a quick measurement on a squirrely baby or child, but they do not provide a very accurate number. If you are determining calling the doctor or giving medication based on this number, it is best to use another route instead.

When to treat a fever

We know many parents who instantly treat a fever, no matter what the number or cause is. Child has fever, give Tylenol or Motrin, recheck fever, repeat. This is what many parents are trained to do. We strongly urge parents to take a step back and assess their child further before automatically treating a fever with medications. Again, a fever is a natural bodily reaction to fighting the fever. So, if we are treating right away, we are limiting our own body’s self-defense against these bacteria and viruses, as well as masking the root cause of the fever.

How old is your child? Are they acting irritable? Can they still keep down liquids? Do they seem dehydrated? These are all things to consider before treating the fever. If your child is also experiencing irritability, weakness, lethargic, nausea or vomiting, then treating the fever may be a good idea.

Check out our guide on Tylenol and Motrin being released next week for a great break down of how to dose and give these medications for fever. You can also call your pediatrician.

When to call the doctor

According to Mayo Clinic, call your baby's doctor if your child is:

  • Younger than age 3 months and has a rectal temperature of 100.4 F (38 C) or higher.

  • Between ages 3 and 6 months and has a rectal temperature up to 102 F (38.9 C) and seems unusually irritable, lethargic or uncomfortable or has a temperature higher than 102 F (38.9 C).

  • Between ages 6 and 24 months and has a rectal temperature higher than 102 F (38.9 C) that lasts longer than one day but shows no other symptoms. If your child also has other signs and symptoms, such as a cold, cough or diarrhea, you might call your child's doctor sooner based on severity.

Call your doctor if fever is accompanied with any of these symptoms, as well:

  • Is irritable, vomits repeatedly, has a severe headache or stomachache, or has any other symptoms causing significant discomfort.

  • Has a fever that lasts longer than three days (one day with infants).

  • Appears listless and has poor eye contact with you.

For more information, visit Mayo Clinic’s website.

What to NOT do:


  • Wrap up a baby with extra blankets to break the fever. This is an old and outdated practice, and it can be especially dangerous for infants. It is best to keep them in lightweight, cool clothing.

  • Give ice baths. Giving ice baths will cause shivering, which actually can increase core body temperature! Giving a luke-warm bath is the safest and most effective. The temperature of the water in a luke-warm bath is still lower than a baby or child with a fever, so it will reduce the body temperature safely.

  • Rub down with alcohol. This may seem common sense, but this practice still happens. This can be more dangerous than the fever itself! Do not do it.

We hope this helps clear up confusion that surrounds babies and children with fevers.

Feel free to reach out with any questions!

Jeri Ford, RN, BSN, CPN

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