When do I need to worry about fever in my child?

Posted on May 29, 2021
Author: Dana Crater, MD, FAAP

As a pediatrician, I often get asked, “When is a fever too high?”

The answer is that there is no magic number that makes a pediatrician concerned, but there are some important guidelines we adhere to and questions that need to be answered to determine the next step in a child with fever.

First, what is a fever? Doctors define a fever as any temperature above or equal to 100.4. A temperature of 99 or 100 may be a slight elevation, but it is not a true fever.

Any infant under the age of two months with a fever above or equal to 100.4 needs to be seen right away in the office or the pediatric ER. The reason for this is that if a newborn has a serious infection, unlike older children, they may not show any other signs or symptoms except for the fever.

Infants age 2-3 months with fever should be examined the same day by your pediatrician, but it is not quite as urgent as the newborns, as long as your baby is otherwise smiling, feeding well, and acting well.

For all children older than 3 months of age, when do you need to worry? Do you need to call the doctor right away? Well, that depends.

The height of the fever is not the most important factor to pediatricians when we see a patient with a fever. What we want to know is this:
Are you able to get the fever down with ibuprofen or Tylenol? (Note: the reason to try to reduce fever is to keep your child comfortable. Fever itself is not dangerous in any way, and indeed is a sign of the body effectively fighting off an illness) Does your child perk up and become a little more active when the temp is down? Is he/she keeping enough fluids down to keep his/her urinary frequency close to normal? Is your child breathing comfortably?

If the answers to the above questions are reassuring, then we may tell you that you don’t need to come into the office right away. Keep your child comfortable, push the fluids, and call your pediatrician for any worrisome signs or symptoms, or if the fever lasts longer than 3-4 days. Having said that, it’s important to use your gut instinct. If you are worried, come on in. That’s what we are here for.

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