Everything You Need to Know About Your Child's Fever

Medically reviewed by Karen Richardson Gill, MD, FAAP on May 27, 2016Written by Chaunie Brusie, RN, BSN on May 27, 2016
Fever in children

If there's one part of parenting that’s the most frustrating for me, it's when my kids have fevers. It feels like every time I turn around, one (or all) of my kids is coming down with some kind of mysterious fever.

Fevers are so frustrating because I often struggle with that fine line of knowing when a fever is "good" and when it's time to treat it or seek medical attention.

What is a fever in kids?

First of all, what exactly is a fever in a kid?

Fevers are actually different in children than they are in adults, because their internal temperatures work differently than ours. A child doesn't have a real fever until their body temperature reaches 100.4 rectally.

And yes, the American Academy of Pediatrics (AAP) does recommend that all parents take their baby's temperature rectally for the most accurate reading. I don't know about you, but I've never actually taken a rectal temperature on my kids at home. There's just no way I'm going to do that at home. Maybe I'm lazy, but just as a reference point, if you're anything like me, the AAP also has a helpful chart that breaks down the different kinds of digital thermometers available and how accurate they are.

They recommend rectal thermometers for babies, but oral thermometers are best for older children. A temporal artery thermometer, which is a thermometer that can be placed on the skin on the forehead, is best to use in babies under 3 months old, while children over 6 months old can use a tympanic (in-ear) thermometer. If you use a tympanic thermometer, you have to be sure to place it in the ear canal correctly and watch out for earwax, as it can obscure the readings. A fever is considered anything at 101 or higher when using nonrectal readings.

What exactly is a fever?

Most of us know this already, but it's a good refresher to keep in mind that a fever is technically a good thing. A fever is just a sign that your child's immune system is working by raising the body temperature in an attempt to kill off whatever is making your child sick.

The body works against an "invader" like a virus by activating defense responses through the immune system, including increasing white blood cells and raising the body temperature. Fevers serve an important function for your child when they’re sick, because viruses and bacteria are strongest at body temperature and weaken at higher temperatures. Children and adults are also more likely to rest when they have a fever.

Are fevers dangerous?

In children between 6 months and 5 years old, a fever can sometimes lead to a complication called a febrile seizure.

Doctors aren't entirely sure what causes a febrile seizure, but for some children, the high temperatures in the body can trigger the seizure. Seizures tend to run in families, so if you or your partner had them as children, you should definitely look out for them in your own child.

A seizure might appear like your child is looking off in space or stiffening up for a few moments. It can last from a few seconds to a minute. Let your doctor know if your child is having seizures. Call 911 if your child stops breathing, if the seizure lasts longer than five minutes, or if your child doesn't come out of the seizure. Uncomplicated febrile seizures look scary, but are not dangerous and do not cause epilepsy in the future.

And obviously, because a fever is just a symptom of an illness your child has, the illness itself can be dangerous. No matter if your child has a simple cold or a more serious illness, a fever may also be present, so it can be hard to tell. Monitoring your child closely and calling a doctor when appropriate is the best treatment.

How to treat a fever

The two medications most commonly used to treat a fever are acetaminophen (Tylenol) and ibuprofen (Advil). Different doctors have different opinions on what is best to give babies and children to treat a fever, so you should check with your child's pediatrician or family doctor about what to give your child.

Again, it's best to treat your child’s symptoms and not just treat a fever as soon as it appears. Giving medication to lower a fever will often just "mask" the fever. However, if the fever is making your child uncomfortable, giving medication can help them feel better temporarily.

Dosing will also depend on your baby's weight, and some types of medications are more concentrated than others. Check with your doctor before giving your child any medication.

When to call a doctor

Obviously, complications and serious illnesses happen and not all fevers will be simple childhood circumstances that go away in a few days. You should call a doctor if:

  • your baby is younger than 3 months old and has a temperature of 100.4˚F or higher rectally
  • the fever goes above 104˚F consistently for a child of any age
  • your child is dehydrated or won't take any fluids
  • your child's symptoms get worse, especially if they become lethargic or unusually fussy
  • your child develops symptoms such as a sore and stiff neck
  • your child has a seizure

The takeaway

In general, if your child has a fever, let them rest and provide fluids as much as possible.

With general and mild illnesses, it's best to let a fever run its course and to treat with fever-reducing medication sparingly. Currently the AAP recommends treating the child's symptoms, instead of just treating the fever.

If your child is younger than 3 months old, has a fever lasting longer than three days for older children or 24 hours for babies, or develops other symptoms, call your doctor.

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