Got a Clue What Makes Your Sick Child Get a Fever? (Updated Pedcast)


Welcome to another edition of, the pediatric blog dedicated to the well being of children and families. I’m your host, Dr. Paul Smolen, a board certified pediatrician with 37 years of practice… and counting. Today we are going to take on a topic that every parent unfortunately encounters and needs to master, that of understanding and when necessary, managing fever.

Musical introduction

Fever is a Symptom, Not a Disease

First, let me remind my new listeners about something we have talked a lot about on this blog– the fact that fever is not a disease, but rather a sign or indication that your child’s bodily defense has been turned on, most often because of your child has acquired a new infection.  Fever certainly is an important thing for parents to recognize and pay attention to but it, in itself, is not a disease–just a sign of a problem, a physiologic change that most often signals the onset of an infectious disease. Recognizing that your child has a fever means knowing how to accurately take their temperature.  To learn that, check out my video on the subject, currently my most popular video on You Tube.  My mother is so proud–her son the You Tube star even though she doesn’t have the faintest idea of what You  Tube is!   Anyway, back to fever. In the era of immunized children, a fever in your child is most likely being caused by a virally caused infectious disease, a disease that usually needs no treatment other than time and loving care.   I hope you are starting to relax a little about fever… good.

The Science of Fever

I think it will be useful for you to learn some of the science behind temperature control? Just how does your child’s body control his or her body temperature? For the answer to that we need to take a little detour down what I call, Science Drive.  It goes without saying that having a normal body temperature is extremely important to the good health of your child because there is a very narrow range of temperature that your child’s body will function properly at…too cold, and the child’s metabolism slows down with terrible consequences.  Too hot, and their brain and other organs malfunction, again sometimes causing terrible problems.  The healthy range of temperature in your child’s body is controlled by a part of the brain called the hypothalamus; the thermostat of your child’s body so to speak that is buried deep in their brains. For various reasons, this thermostat works on a day/night rhythm, also called a circadian rhythm where body temperature is slightly higher at night than during the early day.  Sickness alters this near constant set point and exaggerates this day/night rhythm.  That’s why your children are more likely to have their highest fevers at night when they are sick. A group of substances called pyrogens, released from white blood cells when your child is sick, can turn up your child’s body temperature in an instant, just like adrenaline can raise his or her heart rate in seconds or insulin can lower his or her blood sugar rapidly.  This is why one minute your child can act well and literally before your eyes, they can descend into a fever. Now here is an important point for you to remember–raising your child’s body temperature when they are sick, speeds up their metabolism and accelerates their immune response to the infection.  That’s a good thing; the faster your child can have a good immune response to this illness, the quicker they will get back to normal. Your child’s body knows that fever, is usually a shortcut to wellness. But, raising your child’s body temperature very quickly is a big stress on a their body as any parent with a child with febrile convulsions can attest… but that is a subject for another day.

A Practical Approach to Fever-When to Treat Fever

How and when do you, as a parent, need to get your child’s temperature down?  First the when– since fever is a shortcut to wellness in most children’s illnesses, my philosophy is to only to treat fever when the child is very uncomfortable, when the fever is interfering with their sleep and rest, or when a child is prone to fever seizures or has medical conditions, or when a parent is worried that their child is acting very sick and need to get their temperature down very rapidly. I know you will encounter differences of opinions from other pediatricians, parents and grandmas about that my minimalist advise about fever treatment but that has been my approach for a long time and it has served me well.

A Practical Approach-How to Treat Fever

So now for the how to lower a child’s body temperature. Actually this is done the same ways you control your overheated house…  by either turning down the thermostat or by opening the windows and letting the heat out.   Let me explain. When confronted with your feverish child, you can do the same thing as when your house is too hot.  Acetaminophen, ibuprofen, and similar medicines literally turn down the thermostat in your child’s brain.   Their body’s temperature “set point” is lowered by these medicines just as you would do by lowering the thermostat program, thus turning on their cooling mechanisms.  Similarly, a tepid bath, consuming cool drinks, and sponging with wet clothes transfers heat from your feverish child thereby lowering their body temp, just like opening the windows of your hot stuffy house.  Your Grandma knew that putting a feverish child in a bathtub of lukewarm water gets their temp down quickly. Why does that work you ask? Think about it, when your child’s temp is 102 F and you put them in a bathtub of 75F water, heat is literally sucked out of them by the cooler bath water and the evaporation on their skin.  The water will continue to cool the child until the bath water reaches their body temperature, 102F.  And, you don’t have to use cold water simply any water temperature that is lower than your child’s high body temperature. This is a very quick and effective way of lowering a child’s body temperature, just like Grandma did.   But be aware that the only negative side effect of the bathtub method for a parent is you might need to get into the tub with your child… but that’s not so bad, is it.


So, let’s summarize today’s pedcast:

  1. Fever is not a disease, just a defense mechanism your child’s body uses to speed up recovery from an infection.
  2. Most childhood illnesses today that occur in immunized children, are viral illness usually self-limiting thank goodness. This is why you put your children through the pain of getting all those shots, to prevent most of the serious causes of fever that ravaged so many children in the past.  It turns out that treating the fever that is associated with viral illnesses is often unnecessary and can actually slow down your child’s recovery.
  3. There are a few reasons you might want to consider treating your child’s fever– to make them more comfortable, to prevent fever seizures or physiologic stress in a child with some other type of chronic illness, to try and distinguish serious from non-serious illness. If your child is hot but not uncomfortable, I prefer not to lower their body’s temperature because this may slow their recovery from the infection.
  4. Parents have two choices when they have decided to lower a child’s body temperature, pharmacologically turning down the thermostat with ibuprofen or acetaminophen or physically removing heat, usually with water baths.

A Word of Caution

You need to remember that fever can signal serious trouble such as when your child has the combination of fever and rash, or an extremely high fever (105 or greater), or when your very young infant has fever, especially those under 3 months of age, or when a child has fever for more than 3 days, or when fever occurs in combination with any localized symptoms such as chest pain, a swollen joint, a stiff neck etc. etc..  These are a few situations (certainly not all of them) where fever can mean serious trouble and should not be ignored. For more advice about your child’s fever, call or visit that wonderful person you call your child’s pediatrician.


I hope this pedcast continues your pediatric education and makes you a little more confident the next time your little ones have an elevated body temperature. If you want to learn more on the topic of fever and children, take a few moments to read or listen to other pedcasts on the subject:




As always, your comments are welcome at my blog, and on iTunes. This is Dr. Paul Smolen, recording in studio 1E, hoping you don’t go wild, the next time you have a sick child.  Until next time.