What they are and when to worry

Probably the biggest concern that we have as parents is when our kids get a fever. It think it's fueled by memories of "brain baking bacteria" that existed (prior to the immunizations we have now) and caused serious neurologic consequences. My intention here is to let you know when I get worried about fevers, what they are, and when to bring your child in. Fever is one part of infection and isn't always bad.

What is a fever anyway?

The upper normal limit of temperature is 100.4 in children. This is a little different than traditional teaching that 98.6 is your normal temperature and anything above that is a fever. We actually have a range of temperatures during the day, with our lowest occurring at about 6:00 am and the highest usually at night, around 6:00 pm. This variation in temperature is normal and expected.

How am I supposed to check the temperature?

Well, ideally, the mercury thermometer in the rectum for 3 minutes (yes, three minutes!) is the gold standard. All other ways of measuring temperature are OK, but not as good. I always get questions about ear thermometers. They are about 70-80% accurate, but they have to be placed correctly. And, I'm not sure how accurate the temperature needs to be.  If they are hot, unhappy, and the number is about like 101.5, then any other number doesn't matter too much.

But food for thought:  your child should be acting sick when you check that temperature.  A happy kid, playing, smiling and eating doesn't need to get their temperature taken, even if they feel warm. The number for the temperature, if it's high, will make us worry.  And we have enough to worry about.  I would like the temperature to be part of the picture, not the whole thing.

So what temperature will bake my child's brain?

I'm not sure. The limit of physiologic temperature regulation is about 106 degrees. That means that the brain systems that control temperature won't let you get to a temperature that's higher than 106 if all is working right, and everything is working right in the great majority of children. Many of you have heard me say that you can't get to a temperature that will hurt you without the help of cocaine or general anesthesia- it's my weird way of saying that temperatures higher than normal physiology need help to get there.

There is a very strong temptation however, reinforced by years of getting our own temperature taken, to believe that an increasing fever means that the child is getting sicker and that a decreasing fever means they are getting better.  And so we check, hour after hour, to see where the fever is going.  Keep in mind though that some of the most evil diseases in childhood occur with no fever at all.  And some of the most common childhood viruses, like the one that causes roseola, cause very high fevers. Bunches of kids get the disease, and they are all pretty much all right.

I guess I'd like to tell all of you, officially, if the height of the fever is going to make you really nervous, then don't check it.  Keep the kids comfortable, and watch them, not the fever.  I get more worried about kids acting sick, rather than measuring sick.

Causes of Fever

The actual significance of fever is the source.  We spend a bunch of time figuring out what caused.  Once we have the course, then the number f the fever doesn't much matter.  And immunizations have made that change in thinking.  Fevers are most often caused by a virus or a bacteria.  The most ominous fevers signaled serious disease because the came from dangerous bacteria.  We immunize against those bacteria.  We worry a lot less about fever in an immunized child.  If your child is not immunized, then the fever is something that needs careful evaluation.

The fever is the body's response to the presence of the infection.  It's our immune system that causes our temperature to go up in an effort to make an unpleasant environment for the bacteria or the virus and make it more difficult for the infection  to continue to replicate.

There is an important difference between the viruses and bacteria. In general, viruses go away by themselves, and bacteria need medicine (antibiotics) to go away. Antibiotics do not help viruses. And the great majority of fevers are from viruses.

However, since most childhood illnesses are caused by viruses, we have no medicine to make most illnesses go away. We can help your child feel better symptomatically, but viruses go away without help-- the so-called "running its course." The challenge is always to determine who has a bacterial infection and who has a viral one.  Believe me, it does not make me feel warm and fuzzy when I say that your child has a virus.  I would love to give a prescription for something, anything, that would make the illness go away quicker.  But I firmly believe that if your child does not need antibiotics, they should not get them. And until modern medicine catches up with the common cold, we'll have to do with popsicles, TLC and the remote control.  I'm not a big fan of over the counter cold medications except the stuff we have on the medication page.  And "big fan" might even be a stretch for those medications.

Similarly, whether or not the fever responds to acetaminophen (tylenol) or ibuprofen (Motrin and Advil) and for how long it responds is of little value.  Neither one of those medications has any infection-fighting potential.  They are for making kids feel better.  If your child has a fever, but doesn't act sick, they don't need medication. 

Fever by age: Birth to 3 months

This is the age group that has the highest chance of having a serious bacterial infection, therefore it's the age group that we worry about the most when it comes to fever. Any child under 8 weeks of age with a fever greater than 100.5 rectally should be seen and seen soon. This age group can have bacteria from the birth process that cause serious infection, and often needs serious testing to discover the source. Often, a catheterized urine specimen, a blood culture and a lumbar puncture (spinal tap) are necessary to investigate the source of the fever. Even more confusing is that kids this age may not have a fever, in fact, they may be cold (hypothermic), so if you have concerns about your child's behavior in the absence of a fever, we'll take a look at them then too. Kids under the age of 30 days with a fever are usually hospitalized.

Fever by age: 3 months to 3 years

Again, the challenge here is to figure out who's got a bacterial infection and who has a fever because of a viral infection. This age group has a lower chance of serious bacterial infection than infants do, but a higher chance than kids over 3 years. It's a tricky age group to evaluate, but that's really my problem ! It's hard for me to give you any general guidelines, but here we go:

General Guidelines

If the fever has occurred for less than 2 days and your child's behavior hasn't really changed, then symptomatic care measures are all that's really needed. This really isn't the age group manipulating you so that they can stay home from school or get the car keys, so how they look is usually how they feel. A child who has a fever, but is playing and drinking is different from a lump on the couch with a fever.

A behavior change usually requires evaluation. Their appetite will decrease (just as ours does when we feel crummy) but they will usually take liquids. Unlike infants, the chance of hospitalization is low but we are still likely to do a catheterized urine specimen (especially in little girls) and blood work, depending on how your child looks.

The fever is one part of the infection. The absolute number of the temperature is a piece of the story but not the big picture.

Fevers come back up when the acetaminophen or ibuprofen wears off- acetaminophen and ibuprofen are for relief of symptoms. They don't cure the illness.

Fever by age: over 3 years

This age group has the lowest risk of serious bacterial infections. The general guidelines above are good guidelines for this age group too.

A little extra help:

Call the office immediately if :

  • Your child looks or acts very sick
  • The fever is 105. I know I just wrote that the height of the fever doesn't bug me, but call us anyway.  If you took the temperature, you must have been worried, and we should chat.
  • Your child is crying inconsolably
  • Your child is difficult to awaken
  • Your child cries if you move or touch him
  • Your child's neck is stiff
  • Any purple spots are present on the skin
  • Your child is unable to swallow anything and is drooling saliva
  • You have questions or concerns