Fever facts for kids
Fevers in kids are one of the most common issues that we see as pediatric providers, and it’s one of the biggest causes for concern for parents. No doubt, it’s scary to watch your child be sick. And it’s scary to see them get hot and be miserable.
Understanding what a fever actually is might make you a little bit more comfortable with it.
Fever accounts for about a third of all the pediatric conditions we see in the office sick visits.
Here’s what parents need to know about fevers in children
The normal body temperature, as we all learned in high school biology class, 98.6 degrees Fahrenheit. In reality, 98.6 is the average of several healthy, normal, adult individuals. It’s not really a temperature that we all have to be at, and it’s certainly not a temperature that is necessarily normal for everybody.
Your normal body temperature is affected by a lot of different things.
- Time of day when you’re measuring the temperature
- Hormone levels
- Activity levels
- Menstrual cycle for women
What typically happens throughout the day is that your normal body temperature is coolest in the morning and then hottest in the evening. Your temperature can actually vary by up to one degree throughout the entire day, and that’s just when you’re feeling normal.
Babies and toddlers tend to have a higher normal body temperature than older kids and adults. Mostly this is because because they have a greater surface area to body weight ratio. They’re smaller and their weight is smaller, but they have a lot of surface area where they can give off heat. They just tend to be hotter. They also have very active growing tissues and growing tissues give off heat. They just tend to be hot.
In a newborn, which we define as a baby between the ages of zero and three months, their normal body temperature can actually be in the 99s. So 99.5 is actually normal for a lot of babies, but having said that we like our newborns to be within a certain window. So 97 to 99 tends to be more of a normal temperature for them.
What is considered a fever for adults?
The definition of fever for adults is 100.4 degrees or higher of a core body temperature. The gold standard for measuring temperature is rectally, which is not the most comfortable, obviously. We do this more for babies and for toddlers because we want to get their core body temperature, and it’s hard to do that any other way.
In older kids and adults, clearly the more comfortable way to do it is through an oral thermometer. That’s another good way to measure a core body temperature, but really the best way and the gold standard is rectal.
Until what age should parents take a rectal temperature on a child?
Up to age three is actually the common recommendation. That said, parents should do what is comfortable and report the method of measurement to your pediatrician.
Is fever a sign that there’s something going wrong with a child?
A fever itself is not a problem. It’s really the sign of a problem. A lot of parents will understandably focus on the fever feeling like that’s really the big issue. For pediatricians, the fever is really more of an indication that there is something going on, something else. Usually that something else is an infection.
Most of the time infections are caused by viruses or bacteria, which are organisms that will use your healthy body to grow and sort of help themselves to survive, so they make copies inside you. It really is sort of an attack on your body.
When your body’s attacked, it activates what’s called the immune system, which is kind of the military for your body. It helps to protect you. When your body’s attacked, one of the first things it will do to sort of signal that there is this invasion is produce a fever. It produces a fever for a number of different reasons.
One of the best reasons for a fever is that the hotter body temperature can actually help slow down the growth of these viruses and bacteria, which can help of course, to reduce that infection and help you not to be as sick. That’s one reason.
It also helps increase your metabolic rate. It increases things like your heart rate, your blood pressure, your breathing rate, your muscle tone, activity, things like that in order to help you to sort of fight off whatever is infecting you.
The increased muscle tone and activity also produce the shivering and the chills. A lot of parents will worry that the child is having fevers and they’re sort of shaking and shivery. The shivering is actually a normal part of fever. It’s just your body trying to warm itself up and fight whatever’s infecting it.
Your body tries to decrease heat loss through your skin, which is why your hands and your feet tend to be very cold and clammy when you have a fever and the core part of you where your organs are, where your head is, will be much hotter.
It can produce these chemicals in your blood that induced slow wave sleep, which is why when you have fever you feel really tired. It also produces chemicals that can cause muscle aches and joint aches, which is why a lot of people feel very achy when they have fevers.
All of this activity tends to increase fluid loss. You’re breathing really hard. You’re sweating all these different things are happening. So that can make you dehydrated, which is why it’s very important anytime you have a fever to make sure that you are drinking well.
Fluid intake is part of the healing process, and it helps to recover from all of these things that your body is going during a fever.
When to call the pediatrician about a fever
In any baby, less than two months old, any fever is an emergency. Whether it’s been there for an hour or longer than that, either you need to call us or you need to just take your child to the emergency room. Although we prefer that you call us.
Newborns have a risk of serious infections, just because of their weak immunity. They tend to be a little bit more helpless when it comes to infections, and they get sick really quickly. If they have any fever, we need to know. Most of the time, what happens is we will send babies to the hospital to get tested and they need to have all of their body fluids tested.
We test blood, urine and the spinal fluid, which can be very difficult for parents to see. But it is important because those are places where serious infections can lurk. Unfortunately, a lot of times these babies do need to be hospitalized until the testing shows that they don’t have a serious infection. Even if everyone in your house has a cold and your baby seems to have the same cold, they still need to go to the emergency room and have most of the time because there can also be a serious infection.
That’s one of the reasons why we don’t ever want parents to give Tylenol to a newborn less than two months old without calling us first because we don’t want to mask a fever. It’s also a reason why you want to limit visitors to really just kind of close family. Just to limit infection risk in the first two months of life until they can get those first two months shots.
In babies two months and older, it really depends on how they look. If your child is sick with a fever, but otherwise acting like him or herself, eating pretty decently, drinking pretty decently, and otherwise comfortable, and you’re comfortable with that, then it’s okay to watch them at home. We are always happy to see your child, no matter how many days of fever it’s been, if you have any concerns, but if you feel comfortable watching them generally, it’s okay to watch them and give them some Tylenol or Motrin at home.
Red flags when it comes to fevers in children
There are certain situations where we would want to see a child in the office. Most fevers are caused by viruses and viruses are benign sort of cold viruses, croup, that sort of thing. Your body can and will get rid of them on its own. Those fevers tend to last three, maybe four days. If it’s been longer than that, longer than three days certainly, we would like to see the child in the office just to make sure there’s nothing else going on. Make sure they still look really good.
Other red flags. If your child was recently sick and seemed to sort of get better, but then all of a sudden started spiking a new fever, that of course we’d want to see them for because it could be what we call a secondary infection, which is you are sick with one thing and then you get a little better and then some sort of bacteria takes advantage of you. Then you get sick with something else, like an ear infection or pneumonia.
Any fever with a strange rash, we would want to see in the office.
Any child who is feverish and inconsolable, meaning nothing you do makes them better. Then absolutely, we want to see them. It’s normal for them to be uncomfortable, but if they’re completely fussy and nothing you can do can make them stop crying then for sure, we want to see those kids.
If they are not making their normal number of wet diapers, we would like to see them to see if they are dehydrated.
If a child is working hard to breathe, meaning their bellies are going in and out really fast, or they seem like they’re gasping for air, we would like to see them.
If you are giving Tylenol and Motrin and they still look sick, we would like to see them.
Our main goal is to make sure the child is comfortable.
What to do when your child is comfortable because of the medicine
If your child is 104 and you give them something and it goes down to 101, but they’re more comfortable that’s perfectly fine.
Then when they’re comfortable is when they do the things that we want them to do, like drink, and eat, and sleep. Making them comfortable is the point of the medicine. You want to reduce the fever enough so they are doing those kind of normal childhood things.
What is considered a high fever in children
Most fevers never get higher than 106. That’s the highest documented. Fever brain damage happens at about 110. That temperature doesn’t happen from fever; it happens from external things. If you are working out on a really hot day, or if a child is accidentally left in a hot car. That’s the kind of thing that can make your temperature go up that high and that of course can lead to brain damage and death. That’s called hyperthermia, and that is very different.
There is no number that we would say, “Oh, for sure, you need to go to the emergency room.” The most important thing is really how does your child look? How are they acting? Are they delirious? Or are they kind of tired and achy, but otherwise themselves. That’s much more important.
Medicine that reduces fevers
Ibuprofen and acetaminophen are both very effective at reducing fever. There are no studies that show one is better than the other. Ibuprofen tends to last longer than acetaminophen. It can be dosed every six hours as opposed to every four. A lot of us tend to like it better because of that long lasting effect. It is a little bit nicer at bedtime when you can give your child something that lasts longer and helps them sleep longer.
One of the downsides of ibuprofen is that it can cause stomach irritation. It can also cause kidney problems because it is cleared from the body by the kidneys. For that reason because babies have very delicate kidneys, we don’t give babies under the age of six months ibuprofen. We would just give them acetaminophen. Ibuprofen is for six months and older only.
A lot of parents will either ask about alternating Tylenol or Motrin or ask if that should be done. We don’t recommend it. The Academy of Pediatrics also does not recommend it and there are a few reasons why.
There have been a lot of studies that have shown the combination of the two of them don’t necessarily improve patient comfort, which is really the goal. The goal is not to get temperature down, it is to improve patient comfort.
The other thing is it actually can be very dangerous. What happens is because Tylenol, or acetaminophen, is dosed every four hours and ibuprofen is dosed every six, it can be very confusing to remember what time you gave the last dose and what you’re supposed to give next. I’ve done it before. I’ve had to write it down and even then I found it very confusing. Many parents do accidentally overdose their children because they just don’t remember when the last dose was.
The other thing is it can perpetuate this whole fever phobia. It kind of makes the fever the scary thing that has to be eliminated from the child’s body. Like we said, it really is just a sign of something else going on. It doesn’t necessarily have to be completely eradicated by medications.
There is also no evidence that it reduces what are known as febrile seizures. There are some kids, a minority of kids, who will have seizures as their temperatures rise and get higher. Those seizures are called febrile seizures. They are caused just by fevers. Some practitioners think that if you alternate Tylenol and Motrin, to try to get those fevers down, that can reduce the incidents of febrile seizures. That has not been shown to be the case. A lot of people will not recommend doing that.
The best advice I think and what I try to tell patients is stick with one. Choose either acetaminophen or ibuprofen, make that the one that you’re going to give, know how often you should be giving it, and when it’s not time for a dose, if your child is uncomfortable, sort of in between doses, then you can use the other one for breakthrough.
What about fevers with vaccinations?
A fever with a vaccination is actually a good sign. It means that the body is responding to these vaccines and creating a reaction. The point of the vaccine is to rev up your immune system so that you create these antibodies, which are your body’s way of protecting itself against these invaders that come in.
When your immune system is revved up, like we said in the beginning, you end up getting a fever and so the fevers can be normal. They’re actually a good sign that your immune system is working. Those fevers tend to last for maybe 24, 48 hours. So if your child had vaccines, but then five days later has a fever, that fever is probably not from the shots.
Again, if your child has fevers from vaccines, I would treat them with either acetaminophen or ibuprofen just to make them comfortable. Again, your goal is not necessarily to reduce the fever, but really just to help your child be more comfortable. There is actually evidence, some evidence, that if you pre-medicate with acetaminophen or ibuprofen, it can actually interfere with the immune system’s response to the vaccines. We don’t recommend that you give your child medication before they come in for their shots.
Having said that, there are some children who always have reactions and who are always miserable after fever. We would want them to be comfortable if you want to pre-medicate them of course you know them best so do what makes sense for them, but you don’t have to pre-medicate.
Can teething cause a fever?
Teething does not cause fevers. If we’re talking about fever as being a temperature of 100.4 or higher, teething does not cause that. Again, the vast majority of the time it’s an infection.
What usually happens is a baby is teething and so they’re putting everything in their mouths. They put a virus or something that gets them sick in their mouth, and that gives them the fever. It gets sort of miss attributed to the teething, but the teething process itself does not cause fevers.
That age group of kid also typically gets a lot of what we call viral fevers or viral syndrome with fever. Those kids in that age group typically don’t have a lot of other symptoms with these febrile illnesses. They just have a fever for a little bit, one to three days and the fever goes away. It’s very easy for parents I think to attribute that to teething because they didn’t see any big cold symptoms or other things going on.
If you have questions about your child’s fever, give us a call at 847-676-5394, come to the morning or afternoon walk-in hours or make a telehealth appointment.