I recently saw a video come across my newsfeed advertising a device you can stick to your child that will continuously monitor their temperature and Bluetooth the readings to your smart phone.  The app will alert you when your child’s temperature is “too high”.  You can even email your readout to your pediatrician!  It will save lives!  My eyeroll was strong on this one.  That’s right, cash in on parents’ fears, make my job even harder.  Screw you, Blue Spark Technologies.  Screw you, CNBC for promoting this garbage.  Clearly we are not getting through to people about fever.  OK, time for a blog post.  Here we go.

First off, I’d like to apologize to all the parents out there we have confused over the years.

So, you have a baby.  Your baby is the most magical, perfect, beautiful little being you have ever beheld and you are overcome and besotted.  You are now responsible for the safety and well-being of this little critter so you pay very close attention to the instructions you are given in the hospital.  And what do they tell you about fever?  IT’S BAD!  If your newborn has a fever, get thee to the emergency department post haste!  Do NOT give Tylenol, do NOT call your mom for advice, do NOT give them a lukewarm bath, GET THEIR BUTT TO THE ER RIGHT NOW!!!  It’s like we seem to think that fever is some sort of emergency.  It is . . . in a newborn.  But here’s the thing we don’t explain very well – it’s not the fever that is the emergency.

In a newborn, as in any human, fever is a symptom of disease.  It is part of the human immune system’s strategy for fighting off invading germs.  It is a signal that your immune system is feeling threatened by something.  In a newborn, they might not give us any clues about what that threat might be.  A fever could be a symptom of anything from a common cold to meningitis to a urinary tract infection (which in a newborn is actually really serious) to a stomach virus, it could be anything.  Newborns have an underdeveloped immune system and they haven’t been vaccinated yet (except for Hep B, but I digress).  Thus, they are at much higher risk for serious bacterial infections (SBI).  A newborn with meningitis can go from first fever to dead in a matter of hours.  So if your three week old baby has a fever, they need to be seen by a physician right away.  Even so, the fever itself does not pose any danger to the baby.  This is where many parents get confused.  They get the impression that since we are so hung up on temperature in newborns, that must mean that the fever is going to hurt their baby.  We start breeding fever phobia in the first 24 hours of life because we don’t explain the reasons for our recommendations.  Even worse, I’ve met parents who measured a fever in their newborn but didn’t seek medical attention because they were able to “get the fever down” after a couple of hours.  They assumed that resolution of fever means the threat has passed so everything is OK.

Fast forward a couple of years.  Now, your 2 year old spikes a temp of 103.7 in the middle of the night.  Oh no!  They told you in the hospital that fever is an emergency and your grandma told you that high temperatures cause brain damage, this is very very bad and you’re scared and you don’t know what to do.  You call your doctor’s office and the answering service patches you through to the doctor.  A scratchy voice on the other end of the phone asks you all sorts of questions about your kid, then tells you to give them some Tylenol and go back to bed.  Maybe they DO tell you to go to the emergency room, so you go and a doctor comes to examine your child.  They don’t do any tests or anything!  They tell you your kid has “justavirus” and send you home!  They don’t even give her any medicine!  But she had a fever!  She had a really high fever!  When your friend’s baby had a temperature that high they admitted him to the hospital and gave him IV antibiotics and kept him for two days.  They did a spinal tap and everything.  What gives?  Here’s the deal, parents – the number does not matter.  The reason for the fever matters.  Once we have determined the cause of the fever, we don’t care about the number anymore.  A newborn could have meningitis so we do lots of tests and cover with antibiotics just in case.  In a toddler, we can almost always tell if they have a serious illness based on physical exam without any labs or x-rays.  Most of the time they’ll have a viral illness for which we have no treatment.  So we’ll reassure you that your child does not have a serious illness and recommend comfort measures.  Hopefully we will also counsel you about signs of serious illness you should watch out for.

Are you still confused?  I don’t blame you.  Let’s talk details. (Note, all temperatures are in degrees Ferenheit.)

Myth: Fever is a sign of serious illness.

Fact: Fever is a very generic indicator of infection.  Thousands of different infections can cause a fever, everything from the common cold to ebola.  The important thing is to determine the underlying cause of the fever and doctors use other clues to figure this out, not the fever itself.  How high the fever got, whether it went away with medication, whether it came back up after the medication wore off, none of those bits of information help me determine the underlying cause or how serious it might be.  However, there ARE some features of fever that are useful to note.  First, how many days in a row has your child had fever?  Your average virus will cause fevers lasting 2-3 days.  Beyond 3 days, I want to see that kid, regardless of other symptoms.  I may want to see them a lot sooner depending on other factors (discussed further down).  Second, did your child have a fever for a day or two with a viral illness and then no fever for several days and then the fever came back?  That could be an indicator that something new is going on, like a secondary bacterial infection.  I want to see that kid too.  In either case, it could still be a minor illness but I at least want to have a look.

Myth: The higher the fever, the more serious the illness (sister myth – high fevers are more likely to be caused by a bacterial illness as opposed to viral illness).

Fact: Nope.  Just nope.  A newborn with a temperature of a 100.9 could have life-threatening bacterial meningitis.  A 2 year old with a temperature of 104.3 could have roseola (an utterly harmless viral infection).  I just want to know if a child has fever at all, the number is really not important.


Myth: If I can get the fever down with medicine, it means the cause isn’t serious.

Fact: Not so.  Even if the temperature comes back down to normal, if your kid is lethargic or hasn’t peed in 12 hours or is breathing twice as fast as normal or is under 8 weeks old, I don’t care what their temperature is after Tylenol, get thee to the emergency department.

This brings me to another common misunderstanding about fever.  Fever may not be continuous during an illness.  Fever tends to spike in the afternoon and evening and resolve in the morning.  A child may have fever at bedtime, wake up with no fever and feel great all day only to have the fever come back around dinner time.  This has to do with your body’s fluctuating cortisol levels.  What’s cortisol?  It’s a hormone (i.e. signalling chemical – not all hormones have to do with sex and puberty) released by your adrenal glands.  Cortisol has a lot of different functions and affects numerous organs and processes in your body.  It plays a role in metabolism, helps regulate blood sugar, helps to regulate electrolyte levels in your blood, and it suppresses inflammatory processes.  That last bit is what we care about in this discussion about fever.  The body’s inflammatory process is kind of like it’s alarm system.  It is the initial process that turns on the immune system, if you will, so that it can fight infection or get rid of tumor cells or parasites or support wound healing, etc.  Part of that immune system mobilization process is fever.  Cortisol levels fluctuate naturally throughout the day – they are higher in the early morning and drop in the evening.  Thus, fever tends to appear at night, go away in the morning, and return the next evening.  Once fever has stayed resolved for more than 24 hours, you can feel confident that the immune system has gotten the upper hand (and/or the treatment is working) and your munchkin should start to get better, at least if we’re talking about typical childhood illnesses that don’t make them sick enough to land in the hospital.

Myth: 98.6 is normal body temperature.  Therefore, anything higher than that is a fever.

Fact: 98.6 is average human core temperature.  Some humans live at 98.4, some live at 99.1 . . . on AVERAGE.  As mentioned above, your body’s temperature fluctuates throughout the day.  It is also affected a bit by environmental temperature, how heavily dressed you are, etc.  Fever is defined as a core temperature of 100.4 or higher.  In infants under 4 months of age, it is important to obtain an accurate temperature and that means rectal.  Yes, in the butt.  Yes, you have to stick the thermometer in there.  You can do it.  I believe in you.  Over 4 months, rectal is still the most accurate method for measuring temperature, but since we already understand that the exact temperature doesn’t really matter, I’m not going to harp on it.  Arm pit is fine, as is under the tongue. (Please do not use your rectal thermometer to measure an oral temperature.)  If you come in and tell me your 3 year old was burning up last night but you didn’t take a temperature, I won’t judge you.  My kids are 7 and 3.  I don’t know where my thermometer is.  This drives my mother crazy.

Myth: Fever is good.

Fact: Fever is part of your immune system’s strategy for fighting invading germs.  There are a few studies showing that if you don’t treat the fever, your body may fight off a viral infection a bit quicker.  So yes, fever helps your body fight infection and it’s not dangerous so let it burn, right?  Well . . . not necessarily.  I want to talk about this one because there are those out there in social media land who will shame you for giving your kid a friggin’ dose of Tylenol when they have a fever.  While I don’t want parents to be afraid of fever and I understand that fever fights viruses, there is no benefit in letting your kid suffer in misery all night long.  Sleep helps them heal too, y’all.  Treat the kid, not the fever.  If your child is happily rockin’ out (or comfortably sleeping) at 101.7, let it ride.  If your child is uncomfortable at 100.9, break out the drugs.  Also give them lots of cold fluids to drink, don’t over-bundle them but don’t make them freeze either.  A warm bath can be nice and soothing as well.  You do not need to do what I call “chasing the fever”, i.e. alternating acetaminophen and ibuprofen every 3 hours to keep the fever “under control” (although I do advocate this strategy for pain control sometimes).  Again, the fever isn’t harmful.  Fear is harmful.  Fear impedes judgment and that leads to unwise decisions and that causes harm.  Don’t fear the fever.  Keep your kid comfortable.

In that same vein, you don’t need to give your child a dose of Tylenol or ibuprofen before vaccines to prevent fever.  Fever isn’t harmful, remember?  Preventive fever medicine may actually decrease their response to the vaccines and make them less effective, so cut that out.  If they do get a fever after a vaccine AND they are uncomfortable, by all means, given them some medicine.


Myth: Fever can cause a seizure in anyone and I must control the fever to prevent a seizure.

Fact: About 4% of children will experience a febrile seizure at least once in their childhood.  Kids who have typical febrile seizures almost always have a family history of febrile seizures.  They usually start somewhere in toddlerhood and resolve by kindergarten.  They follow a specific pattern and they cause no lasting damage to the brain or any other organs.  I’m going to say that again.  Febrile seizures do not cause damage.  They are very very scary to witness for caregivers, but they are not dangerous.  Febrile seizures will typically occur with the first fever of an illness.  The seizure will occur before caregivers even know the child has a fever (i.e. there is no way they could have prevented it).  Children who have febrile seizures will typically have one seizure per illness, maybe two, even if they continue to have fever off and on for several days (i.e. “keeping the fever down” for the remainder of the illness does not prevent further seizures).  An uncomplicated, simple febrile seizure will last less than five minutes and children will be back to normal after a few hours.  Epilepsy (seizure disorders) is a different entity.  Children with epilepsy may have their seizures triggered by fever and their neurologists may have different advice about managing their fevers. If your little one does experience a seizure for the first time, with or without fever, do seek immediate care.  I don’t expect parents to diagnose simple febrile seizures on their own.  But still, don’t fear the fever.

BUT DOC, my grandmother told me that when she was a little girl her neighbor’s baby had a high fever of 104.7 and had a seizure and the baby had brain damage and died a few years later.

Myth: High fever causes brain damage.

Fact: High fever causes brain damage . . . but grandma’s definition of high and mine are different.  Temperatures higher than 107 can indeed damage organs, including the brain.  This can happen in cases of severe dehydration (e.g. hikers lost in the desert, athletes with heat stroke, etc.), in children who have damage to their hypothalamus and cannot regulate their temperature (e.g. genetic disorders, cerebral palsy).  It does not happen in otherwise healthy children who are fighting off an infection.  Your brain is smart.  It will not fry itself.  Even if you do nothing whatsoever about the fever, it will not keep going up and up and up.  It will peak at 104-105 or so and just sit there.  Your body will start to sweat, to dilate peripheral blood vessels and shunt blood away from the core.  Your body is very good at regulating its temperature.  So what happened to that baby your grandma told you about?  They probably had bacterial meningitis.  Bacterial meningitis used to be much, much more common than it is now.  And it was devastating.  We have been able to dramatically reduce cases of this horrific disease through vaccines, screening for and treating group B strep in pregnant women, etc.  Back when Grandma was a kid we didn’t have these interventions.  It’s important to understand that it was the infection that harmed those babies’ brains, not the fever itself.

Myth: If my child has a fever and I give them fever medicine, the fever should resolve.

Fact: If your child has a fever and you given them fever medicine, the temperature can be expected to come down about 3 degrees.  Thus, if their little brain has set a goal for itself of 104 and you give Tylenol, it may only come down to 101, and that’s OK.  The point is to make your little one more comfortable.  Being able to get the fever down does not mean the illness is less serious and does not define your worth as a parent.  Treat the kid, not the number.  Then put the thermometer away and go back to bed, call me in the morning.


CAVEAT: There are some children for whom fever is always an emergency.  These are kids who do not have a fully functional immune system and are thus at much higher risk for serious infections that can progress very quickly.  This group includes newborns (babies under 12 weeks of age), children undergoing chemotherapy, children with immune disorders (immunodeficiency syndromes), children with sickle cell disease, children who have undergone organ transplants, etc.  These children are playing by a different set of rules and their doctors should be counseling their parents about this.  I would consider children who are not vaccinated to be in this category as well.

OK, are you tired of talking about fever yet?  Well, tough nuggets because we’re not done yet.

So, if the height of the fever doesn’t really matter, how do I decide when to bring my child in to be seen?  How do I decide if I need to take them to the emergency department?  You probably already know this by now but there is no cut-off temperature.  OK, OK if your child has a temperature over 106 go to the ED.

Your kid has a fever.  They are fighting an infection of some sort, most likely.  Now you have to make some decisions after gathering more information.

Reasons to come see me (your regular doctor):

  • Fever (most likely intermittent) persisting beyond 3 days
  • Cough and congestion persisting beyond 2 weeks
  • Fever that was present at the onset of illness, went away for several days, then returned (Remember that bit about the fever being gone for more than 24 hours?  How that tells you things are getting better?  Well, if it comes back later, that could be a signal that the immune system is fighting a NEW threat, like a secondary bacterial infection or even a new virus.  I want to see that kid.)
  • Focal pain such as ear ache, severe sore throat, severe knee pain, etc.
  • Vomiting several times, especially associated with significant abdominal pain
  • Malaise (decreased energy, aching all over, like when you have the flu)
  • Rash
  • Blisters all over the mouth or throat
  • Wheezing (without respiratory distress)

Reasons to seek emergency care right away:

  • Respiratory distress – this looks like breathing a lot faster than usual, retractions (sucking in above the breast bone or between the ribs, using abdominal muscles to breathe), flaring the nostrils or grunting in a baby (we call it grunting but it’s really more like a groaning sound with every exhale) , stridor (a squeaking, gasping sound with inhalation)
  • Dehydration – watch the urine output – If your baby is peeing normally, they are hydrated. If it’s been longer than 8 hours since they urinated, call me.  I’ll also want to know if they are making drool and tears.
  • Lethargy – your definition of “lethargic” and mine are different. Parents use that word all the time to describe children that I would call “listless” or “sleepy” or “less active than usual”.  When I say “lethargic” I mean I have a hard time waking them up, they are acting like they are drunk, falling down when they try to walk.
  • Very severe pain – doubled over from abdominal pain, having the worst headache of their life, etc. In babies and toddlers, watch for extreme irritability, cannot be consoled by any means, etc.  Fluctuating between extreme irritability and lethargy makes Doctor Kate REALLY NERVOUS and when I’m nervous, you should take that seriously.
  • If you aren’t sure whether you need to go the ED or not, call your doctor’s office. Be ready to tell them all the details (as in all those other symptoms we’ve been talking about, not the hour-by-hour temperature play-by-play, OK?  OK.  Thank you.)

I hope this answers all your questions and addresses your fears about fever.  If it doesn’t, leave me a comment and I’ll get you some more information.  Now imagine me riding off into the sunset with “Disco Inferno” playing in the background.

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