Fevers in Children: What to Do & When to Worry

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We’ve all been there. Our child feels a little warmer than normal, and we think it’s probably a fever. It’s late at night (of course). What to do?

In this post, I’ll cover what a fever is and why kids get them. We’ll also discuss what to do if a child has a fever and how a fever affects the body. If you’re short on time, just scroll to the “summary” section at the end. For a bit more details, read on. 

When is a high temperature actually a fever?

In kids, a fever is defined as 100.4°F (38°C) or higher. While the number on a thermometer may be alarming, it’s often nothing to worry about. Usually, a fever is just one symptom of some kind of infection. It’s not an illness itself.

There are more rare causes of fevers too, but often they often have many additional symptoms, and the fever can last for more than a few days. Today, I’ll focus on the most common fevers in kids, those caused by infection. 

Reasons a Fever Should Prompt a Call to Your Child’s Doctor Now

First, there are a few situations where a fever alone is definitely a reason to call your child’s doctor. If any of the following apply to you right now, please stop reading and seek medical attention:

  • Any fever (temp 100.4°F or more) in a baby less than 90 days old 
  • A fever that has lasted for more than 72 hours (in a child older than 2 years)
  • A fever that has lasted for more than 24 hours in a child between 90 days and 2 years old
  • Temperature is higher than 106°F
  • Temperature is repeatedly over 104°F
  • If a child could be overheated from their environment or activity (example: from sitting in a hot car or exercising in heavy clothing)
  • Fevers that come and go for weeks (this could indicate something other than infection, but not necessarily so)
  • A fever with a compromised immune system (includes sickle cell disease, cancer, some other chronic illnesses)
  • A fever with other symptoms*

If none of the above apply, read on. Again, a fever is a typical response to an infection. Infections in kids are usually caused by bacteria or viruses. A few examples are an ear infection, a cold, the flu, a skin infection, or a urinary tract infection.

How is a fever helpful?

Here’s the amazing thing. The immune system has many ways to fight such infections. One way the body works to fight the infection? Raising the temperature. Many bacteria and viruses won’t thrive as well at higher body temperatures. These higher body temperatures are also known as  . . . fevers! The fever also stimulates the immune system itself. (Some studies have shown increased survival of infections in intensive care patients when fevers were not treated). 

In other words, a fever in an otherwise healthy kid can be a sign that the immune system is doing its job. So, if a child is content, hydrated, and has a fever? Consider letting them just rest with this higher body temperature. There may be no need to treat a fever just for the sake of  . . . treating a fever. (By treating a fever, I refer to giving anti-fever medicine at home).

To be clear, I am not advising that we ignore a fever completely. It’s useful information! If a child has a fever, I advise a parent to keep track of when the temperature was measured and what the number is. This is helpful for many reasons. This way a parent will know if their child has gone 72 hours with fevers. After 72 hours, it’s a good idea to at least call their doctor (as mentioned above). 

The way we approach a child who has had a fever for one morning is different than for a child who has had a fever for 3-4 days. 

When should we treat a fever with medication at home?

All this being said, many kids are uncomfortable at these higher temperatures. They may feel listless. They may not want to eat or drink. Or, they may have some vague complaints or aches. In these cases, of course it’s a perfectly fine idea to treat the fever. We treat not because of a number on a thermometer, but because we want our child to feel well enough to drink fluids, rest comfortably, and to ease those vague pains. 

If someone opts to treat a fever with medication at home, there are two usual choices. Acetaminophen (brand name Tylenol or Paracetamol) is a fine option for children over age 3 months. (Remember, a fever under age 3 months, no matter how well the baby looks, is a reason to call the doctor or go to the emergency room). For children over age 6 months, ibuprofen (brand names Motrin or Advil) is an option too. 

What to do if there are other symptoms?

*If there are other specific symptoms with a fever, I do not suggest only observation at home. Remember, a fever is just one symptom. But if someone also has pain (ear pain, belly pain, pain with peeing, etc) and a fever, this may point to an infection. Vomiting or trouble breathing with a fever are also signs to seek medical care immediately. 

 A urinary tract infection, for example, can be evaluated promptly. If treatment is offered, it is to treat the infection and/or to ease the symptoms (i.e. pain). It is not necessarily just to bring the temperature down to normal. However, once the infection is treated, the fever should also resolve. 

Also, sometimes a parent will feel like their child “just isn’t acting right.” This is also a perfectly valid reason to seek immediate medical care.

Exceptions: When Specific Temperatures Do Matter

I’ve emphasized treating a child based on how they feel as opposed to any specific temperature. However, there are a few situations where we would consider treating just the number on the thermometer. If your child has had febrile seizures, discuss this with their pediatrician.

And, as alluded to earlier, certain chronic illnesses or specific medications require that we approach fevers differently. If this applies to your family, refer to your child’s specialists for how to address fevers. 

Newborns have under-developed immune systems. A fever may be the first sign of something more ominous. This is why any temperature at or above 100.4°F in a baby under age 90 days requires immediate medical care.

Misconceptions About Fever in Children

For all the knowledge we have about fevers, there’s still more to learn. What follows are a few misconceptions that come up frequently.

Brain damage from a fever?

Many parents worry about brain damage as a result of a fever. Higher temperatures, even 104°F, do not cause brain damage in children. Kids with these higher fevers likely feel miserable. They may also be a bit dehydrated. So, after encouraging fluids, it’s fine to treat with acetaminophen or ibuprofen. But leaving it untreated won’t cause brain damage. 

Rubbing alcohol for fevers? Nope.

Some families have used rubbing alcohol massages or baths to help their kids with a fever. This is dangerous and absolutely not recommended. Rubbing alcohol can be absorbed through the skin and can be toxic in children. A regular bath with tepid water is perfectly fine if it seems to make a child more comfortable. 

Will a fever keep rising exponentially?

I’ve received panicked calls at night from parents worried that the temperature will keep rising continually overnight. This doesn’t happen. In an otherwise healthy child, it won’t keep rising to the point of danger. The body still regulates itself even if things do feel out of sorts. Again, though, if a child is uncomfortable, it’s fine to treat the fever! If they are sleeping soundly and have had enough fluids, have been peeing their usual amount (a sign they’re getting enough fluids), and don’t seem to have any trouble breathing? It’s usually fine to let them sleep. 

If a child has specific neurological conditions, their body may not self-regulate as well. This is another example of a situation to discuss with their doctor. I mention it here (along with everything else) for general information.

How does a fever affect the body?

Now that we know what to do about a fever, let’s back up and review how it affects a child. The higher temperature alone can:

  • Make kids uncomfortable
  • Cause them to breathe a little faster than normal
  • Cause them to need more fluids than normal. With a fever, their metabolic rate is higher than normal.
  • Signify that their body is fighting an infection. It also helps fight the infection.

Why does this all matter? It means that focusing on rest and fluids is important in any febrile child. 

If the higher temperature hangs around for more than a few days, it is also important to investigate the fever’s cause. Where is the infection?

Summary: What should I do if my child has a fever?

  • The most important thing is to look at your child. If they are acting unwell or complaining of pain: seek medical attention regardless of the temperature. If symptoms are vague and mild, you can try treating with acetaminophen or ibuprofen (over age 6 months only) at home first. 
  • Keep track of the timing of the fever. If it lasts for more than 3 days (72 hours) in a child over 2 years or 24 hours in a child under 2 years, then it’s time to call the doctor.  Remember to go to the ER if a newborn under 3 months has a fever.
  • Focus on rest and hydration. This is two-fold. They are likely fighting an infection, so rest is important for the body. Fevers themselves can also cause a child to get a bit dehydrated, so extra sips of fluids can be helpful. 

Overall, a fever is just one part of a complex system and usually does more good than harm. As always: if you are worried, please seek medical attention, regardless of a number on a thermometer. 

Maya M. Mahmood, D.O., FAAP is a board-certified pediatrician and mom. She is passionate about parents having evidence-based information to help their families be healthier.


This is for information only. It is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website. See full disclaimer here.


Evans, S. S., Repasky, E. A., & Fisher, D. T. (2015). Fever and the thermal regulation of immunity: the immune system feels the heat. Nature reviews. Immunology15(6), 335–349. https://doi.org/10.1038/nri3843


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