Pediatric Associates of the NW Blogs

Fever Is Your Friend

Jay S. Rosenbloom, MD, PhD
October 28, 2011 11:10AM

It’s 2 am. Your youngest child is upset and crying. And… they’re hot. The thermometer you have reads 102. You’re nervous. Your child is nervous. Fever can feel like your family’s, well… enemy.

Believe it or not, and despite the fear and trepidation often associated with it, fever is often your child’s friend. Fever revs up the body’s immune system and activates it to fight off any viral or bacterial “invaders.” The ability to mount a fever has been shown to increase survival rates in animal species. So, when your child has a fever, it means her body is doing its job. That doesn’t make it easy to understand, though….

Let’s talk definitions first. Until as recently as 1868, there was no consensus on what was a normal body temperature or what was a fever, but now most pediatric experts agree: a fever is a temperature equal to or greater than 100.4 degrees Farenheit or 38 degrees Celsius. That’s why when you make an appointment for your child for a “fever” we sometimes push you on the details: 100.2 you say? Not a fever. Felt your child and thought he was hot but didn’t take the temperature? Might have been a fever, but might not have. We love to know, when possible, the actual temperature.

Your child’s temperature depends on a number of factors, including how you take it. The closer we get to the core of the body, the more accurate it is. That’s why, when we measure the temperature of a baby, we often want to take the temperature in the baby’s bottom. For older kids, a temperature taken in the mouth or the bottom is much more accurate than a temperature taken under the armpit.

A child’s age also matters a lot when it comes to fever. For infants under a month of age, even a really low-grade fever can signal a serious infection from a bacteria. Any child under a month of age needs to be evaluated by a doctor immediately if they have a fever, even if it only occurs once.

As kids get older and older, we pediatricians are less concerned about low-grade, fleeting fevers in otherwise healthy and vaccinated kids, but recommend an evaluation if your child has had a temperature for more than 2-3 days (or anytime you are concerned). About 30% of the visits parents make at pediatric offices for their children are for acute fever, so pediatricians are “fever doctors” a lot of the time!

Some things do worry us when it comes to fever. We worry when the fever lasts several days without a good explanation for it. We worry when your child becomes dehydrated. We worry when your child is lethargic. We worry when your child is not fully vaccinated. Most of all, we worry about how your child “looks” overall, which is why we pay a lot of attention to this when you call or come in. Some things worry us a little less than they worry you. Studies show that parents are often the most concerned when a child has a fever that they will have brain damage, but brain damage has NOT been associated with high fever, even fevers as high as 107 degrees. Sometimes a really high fever can help us figure out if a child’s illness is from a virus or bacteria but that’s not true until the fever gets as high as 106! There are plenty of viruses that give kids high fevers for a few days as well.

It also doesn’t matter if the Acetaminophen or Ibuprofen you’ve been giving to “treat” your child’s fever makes it go away and stay away. These medications are for your child’s comfort but don’t help to fight off the virus or bacteria your child has. If they don’t completely eliminate the fever, it doesn’t mean they aren’t working, just that they wore off like they are supposed to.

Fever can be scary, but knowing what a fever does for the body is helpful. On average, kids will have 4 to 6 acute episodes of fever from birth to 2 years of age, so fever is here to stay, whether we like it or not. Think of it as an (often annoying, but very helpful) friend.