Fort Worth, Texas,
09:35 PM

Let's Learn About Fevers

Dr. Diane Explains What It Is and When To Freak Out

Let’s take a moment to appreciate the beautiful process of a fever. Yes, I’m a mega-dork for the functions of the human body ... and yes, I think fever is a great thing in most settings.

Fever has been recognized as being around for thousands of years. And yet it’s never gone away. We’ve just not evolved it away. Which must mean it benefits us, right?

The process of a fever, simplified/Dr. Diane-ified:

1. A germ (virus or bacteria) enters your body. One of your immune cells floating around notices it. It freaks out. It makes a whole bunch of chemicals to freak everybody else out. HIGH ALERT, EVERYONE!

2. The chemicals reach your brain (the hypothalamus, in particular). The hypothalamus says OK GUYS, GET THE ARMY OUT THERE, STAT. DO YOUR THANG. I'LL MAKE THIS PLACE REAL HOT TO HELP OUT!

3. The brain thermostat is set at a new number. Instead of 98 F, he’s now gonna re-set at 102 F.

4. Heart rate speeds up. Breathing speeds up. Blood vessels open, flush. The body is physically pushing the blood around faster, to get the white blood cells there quicker.

5. Muscles shiver, generating heat. You start making more immune cells. They travel around faster. They talk to each other more effectively. They “stick” to the bad guys better.

6. You feel cold, because your new “set” thermostat wants you to be 102F. You're not there yet, so your body is trying to get you there. You shiver. Your muscles ache.

7. Soon, the germ can’t replicate as much as it wants to. It can't divide and conquer. Maybe even its protective coating starts to break down a little bit.

After a few days of fever, you beat the germ! Thank you, glorious fever and fabulous immune system!

Studies have shown (in rats and iguanas) that there is even a higher success rate at overcoming a virus or bacteria if a fever is allowed to burn rather than when they're given medications to bring it down.

Oh my gosh. Aren’t our bodies amazing? And are you feeling a teeny bit better about that number on the thermometer?

Most of the time, fever is just a sign that the body is fighting something, and you just need to try to keep your kiddo hydrated and comfortable.

You do not have to run to the ER, or my office, at the very first sign of a fever if your child is over age 3 months.

But sometimes, fever isn't OK.

My son once woke up with a fever of 105.7F. I remember the day clearly. I totally freaked out, just like you do. Then I asked myself – what do I tell my patient families to do?

Once I tried a few different thermometers and they all read the same number, I gave him a dose of ibuprofen and put him in a warm bath (NOT cold – warm) and let him play.

I watched him closely. I made sure he was breathing OK, and able to drink. He seemed fine, just super grumpy.

After about 45 minutes, I re-checked his temp. It was 102F. He was sitting on the couch, drinking water and talking comfortably. I was OK with this. And he did fine. He had a fever for three days, and a runny nose and a little cough, and it went away. He had a virus, and his body took care of it.

Is it Time to FREAK OUT?
  • A defined fever, to a pediatrician, is a rectal or oral temp that is over 100.4F.
  • Some of us sit at 99-100F normally. 98.6 is our AVERAGE human temperature.
  • Fever under 108F does not "fry" your kid's brain.
  • Again: Fever under 108F does not cause brain damage.
  • Nothing bad is going to happen if you don’t treat your kid’s low-grade fever. Read that. Then read it again. Yes, he’s going to feel lousy. And yes, you should watch him closely.
  • "Low grade" to a doctor means under 103F.
  • Stop with all the math. "He normally sits at 97 so 98.9 is a fever to him". "I added two degrees since it was a cold day and a measured it in his armpit". Does he feel warm? Has his heart rate sped up? Is he grumpy and feeling cold? He likely has a fever. And not knowing the exact number is OK.
  • It's OK if the fever doesn't come down to normal (or much at all) with that dose of Tylenol or Motrin. It really is. If she’s playing comfortably, drinking water, breathing well….it’s OK to just let it be and let it do its job.
  • Treat your child's fever here and there if they feel bad! Yes, it's OK! Just don't get obsessive about watching the number! Watch your CHILD not the thermometer.
  • Big question I always get: what if my child is sleeping and is burning with a fever? It's OK! Let that kiddo sleep! Chances are excellent that they really NEED that deep sleep right now, and if they're breathing OK, just the sleep and fever do its job. You don't need to go in there to fix it.
  • Give acetaminophen (Tylenol) every 6 hours, or give ibuprofen every 6 hours. I’m not a fan of the constant, every-three-hours approach. If your child is doing OK, no need to potentially overdose them on these medications when the body is just trying to fight the germ off. You don’t have to “fix” the fever.
  • If you don't treat your kid's high fever the day you come in to my office to see me because you "want me to see how sick he is" i'm going to give you this look: Give your kid the medicine. I'm going to believe you.
  • A fever in a baby UNDER 3 MONTHS OLD old worries me. You should call me right away or go to the ER if your baby’s rectal temperature is over 100.4 in this age group.
  • A fever more than 4-5 days worries me. Come in to our office if it's lasted this long. (Though I have seen some mild viruses cause fever for more than 12 days, so it doesn’t always mean something bad is going on).
  • A fever over 103 is considered high, and I usually want to see a child soon (like next day or two).

When do you go to the ER? 

Well, I think anything 106 and higher is worrisome. And even then, if the child is drinking OK, and breathing OK, and is able to talk comfortably with you, then you can call the doctor to be seen that same day.

  • If your child has a fever and is confused, is unable to talk, is unable to drink or urinate, has bad stomach pain, has a hard time breathing, or has a severe headache or stiff neck, you need to go to the ER right away.
  • Most of our brains won’t let our temps over 108F. So if it gets to 108 or higher, I often worry something is actually wrong with the brain, like a brain infection, or a stroke, or ambient heat like a hot car causing it, or some sort of brain damage. Kids with neurologic conditions will often have “too high” fevers because their brain can’t regulate it.

6 Types of Thermometers:

1. Thermometer forehead “strips”, pacifier thermometers, and wearable thermometers - don’t buy them. Save your money. 

2. Forehead “temporal” thermometers – they’re OK. We use this kind in the office. Good days and bad days, and I think they’re usually as accurate as the ear ones.

3. Tympanic (ear) ones – easy to use. Pretty accurate. Don't use under 6 months, ear canals too tiny.

4. Rectal - most accurate (good luck)

5. Oral - second most accurate, if they can hold their mouths shut

6. Armpit - least accurate

Yes, you add one degree to the armpit temp measurements. Although again, I dislike the math.

But what I want to drive home is: if the child looks fine otherwise, the number often doesn’t matter too much to me.

Febrile seizures:

Something like 2-4 percent of kids between the ages of 6 months and 5 years have febrile seizures. This means they may have a seizure when they have a high fever spike. They usually stop by age 5.

These are super scary, but actually don’t cause any brain damage. The child should be rolled onto his side, and watched closely. Don’t stick anything into his mouth.

VERY rarely, unrelenting and long febrile seizures may indicate a bigger problem like something neurologic or genetic going on. But again, this is super rare.

Febrile seizures may run in families. If the seizure lasts longer than 5 minutes, call an ambulance. Again, these are rare, and usually very benign.

Whew. OK. I hope this helps you understand fevers better!

Education is empowerment in your child's health! The more you know, the better you feel!

Have a great day, friends!

Dr. Diane

Want even more on beautiful science of fever? It's all laid out here, with lots of big words and acronyms.

Get to know Diane Arnaout, M.D.

Dr. Diane Arnaout is making the move to the Cook Children's Forest Park practice on Jan. 2, 2019. If you are a current patient family with Dr. Arnaout or want to join her at Forest Park, call 817-336-3800 or click here.  After 7 years at Willow Park, Dr. Arnaout is making the move to Forest Park to be closer to her children, her husband and her parents.  

Dr. Diane Arnaout has been a Cook Children’s physician since 2011. She got her undergraduate degree at Texas A&M University, went to medical school at the UT Health Science Center in San Antonio, and completed her pediatric residency in the Texas Medical Center at UT Health Science Center in Houston. She is board-certified by the American Board of Pediatrics.

Click to learn more.

Comments 1 - 8 (8)
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Anthony Carrino DC
I am quite surprised that there are no supportive comments written here. This was an intelligent and well writen article and something that is rarely seen written by an MD. I applaud your commen sense and the absence of fear and control tactics. Your patients and community are very blessed to have such a dedictaed and open minded individual as their pediatrician.
Melissa Jackson
Hello, my son gets very high fevers (105-107) when he is sick. He has had febrile seizures since he was a year old, he is 6 now 7 in May! His last one was September 2018! We have been back & forth to Cooks Children’s in Fort Worth, ran some different test and everything shows normal with his brain so hoping he is out growing the seizures. We have recently gotten our tonsils & adenoids out as he was having strep every other week here lately. Reading this has helped me understand fevers little better and hoping I will not freak out like I do when he does start running a fever. It’s hard as a parent to not freak but you explaining it as a parent and doctor helps a lot! Thank you for this information!
Melissa Tatum
Thanks for the great read!! Thank you for sharing how you felt as a mom. I think it helps to know that even providers worry and have to “regroup” when their children are sick.
Levon Tilbian, M.D. Pediatrician
Thanks for this interesting and informative presentation. Fever is the most common symptom that bring kids to doctor or ER.But despite explanation to parents about the mechanism of fever and it is the defense of the body against infections ,parents usually don't satisfied and insist to treat fever immediately and prescribe antibiotics especially in developing countries, if you refuse they will search for another doctor.
I agree with you , one should watch the kid not the number of the temperature since most infections of children (except 3 m and younger) are viral and have benign course and only need parents reassurance.
Barbara Chambers
I'm glad that a decent Dr finally tells all about fevers! Too many people get way too crazy over their kids at times like this n common sense let's most people know if n when they need a Dr! God bless n Amen
Dean Coffin
Hi. I am an peds ED RN. Thank you for your clear, succinct article. The article has reinforced the teaching I do EVERY night at work, and reminded me of areas that I should be emphasizing in my d/c teaching.
Thanks again.
My son’s normal temperature is around 97.7
I thought it was odd; but his Pedi says it is ok. So when he is running at 98.6 then; is that a fever?

Also a few times he has dropped to 97.1 at night when it’s cold. His room is on the north end of the house. We keep the inside at a constant 73 degrees, but his room is really cold in the late fall and winter months. I just started putting on an extra t-shirt under his flannel footies. He kicks the covers off so much through the night; it’s impossible for me to keep him tucked under.
Dr. Diane
Thank you for your question Melissa. Our temperature fluctuates daily with activity and environment. “98.6” is what is considered normal but that’s an average – lots of people naturally sit higher or lower on the thermometer. We had to pick a universal “fever”, so we picked 100.4F rectally. So no, even for this kid, 98.6 is not a fever.

Babies will not sleep if uncomfortable temp-wise. So, if they’re hot, they’ll wake up and cry. Same for if they’re cold. The environmental temps that seem most comfortable for babies and kids is 68-72 degrees.

Hope this helps,
Dr. Diane