Children's Hospital Colorado

What Parents Should Know About Fevers in Kids

It can be alarming when your child suddenly spikes a fever. Should you give them medicine right away? Do you need to take them to the doctor? Is there a certain temperature that is concerning? Children’s Hospital Colorado’s pediatric nurse practitioner Krystal Palmer, CPNP- PC, answers all these questions and more, so you can feel confident and informed the next time your child gets a fever.

What is considered a fever?

These are the criteria for fever using different types of thermometers:

  • Armpit temperature: 99 degrees Fahrenheit or higher
  • Oral (mouth) temperature: 100 degrees F or higher
  • Rectal, ear or forehead temperature: 100.4 degrees F or higher

Why does a fever happen?

A fever is like your body’s thermostat — it can help control the internal temperature of your body. It can be a sign of illness or infection, but it can also be triggered by other scenarios where you have an elevated body temperature, such as being in a car that’s too hot or if you are outside in the heat for too long.

Benefits of a fever

In recent years, research has shown that a fever can actually be beneficial. It turns on the body’s immune system to help fight off infections and can even reduce the severity and length of an illness. Because of these findings, medical advice on when to take over-the-counter fever reducers is shifting as well.

When should you treat a fever?

“We typically recommend treating a fever when it is causing discomfort, so we encourage families not to be scared of the number on the thermometer,” Palmer says. “The only time we're really strict on the number of the body temperature is in babies less than 3 months of age, because their immune system is still learning and growing. We like families to call their primary care provider if their baby's less than 3 months of age and has a fever of a 100.4 degrees F or higher.”

If your child is having a lot of discomfort, decreased interest in drinking, pain or lethargy, it could be a good time to use a fever-reducing medication. For children 2 and older, follow the dosing guidance on the bottle. For children under 2, call your pediatrician to confirm the correct dosing for your child, which will be based on weight. Ibuprofen (Motrin) or acetaminophen (Tylenol) are both effective for reducing a fever. In children of any age, you should call your provider when a fever lasts more than three days.

It’s important to make sure your child stays hydrated when they have a fever. For toddlers and older children, offer water, Pedialyte or other oral rehydration drinks. For babies, frequently offer small amounts of their usual formula or breast milk. If you’re concerned about your baby becoming dehydrated, contact your healthcare provider for advice.

“We need to see one wet diaper every eight hours,” Palmer says. “But for babies less than 3 months, if they're not taking their feedings every three to four hours, we want a phone call to be able to assess that.”

What is the best way to take a child’s temperature?

Our team recommends using a digital thermometer for the most accurate temperature reading. As a starting point, caregivers can use the back of their hand to see if a child’s forehead feels warm, but that’s not an accurate measure of temperature. Many other factors can impact how warm a child feels to the touch.

Here are Palmer’s recommendations on the best types of thermometers by age group:  

  • Kids less than one year: The most accurate use of a digital thermometer is with a rectal temperature. If you aren’t comfortable with that approach, you can use a digital thermometer under the armpit.
  • Kids over one year: A digital thermometer under the armpit or in the ear is effective. You can also use a forehead point-and-shoot thermometer for older children.

What is a febrile seizure?

Febrile seizures (a seizure triggered by a fever) are rare, happening in only 4% of young children. They occur when the body’s temperature changes rapidly, triggering a seizure that typically lasts less than one minute. If your child has a febrile seizure, call your doctor right away. But first, place them on the floor or bed away from any dangerous objects and turn their head to the side. Don’t worry about them swallowing their tongue and don’t put anything into their mouth. Call 911 if the seizure lasts longer than five minutes.

Children usually outgrow them by age 5, and they don’t cause any other health issues or long-term damage.

When to seek care for a fever

Just because your child has a fever doesn’t necessarily mean they need to go to the doctor. Palmer says that caregivers should consider what other symptoms a child is experiencing and how long they’ve had a fever before seeking care. Many common viruses, such as the flu, RSV or COVID-19, can cause a high fever in kids for up to three days, and these illnesses can’t be treated with antibiotics.

“A lot of families want to have a number on the thermometer that means an automatic visit, and we just don't really have that,” Palmer says. “The judgment should always be based on how your kiddo is acting versus just the number on the thermometer, unless your baby is under 3 months old.”

Palmer emphasizes that families can always call their pediatrician for advice on the care plan or if your child needs to be seen, but don’t be alarmed based on the temperature alone.

“You can’t have brain damage from our body temperature rising,” she says. “Typically, the body temperatures that we see affecting internal organs are going to be from kids that are strapped in a hot car or heatstroke from playing football in the 100-degree weather rather than an infectious cause.”

For older kids, if your child is staying hydrated and not having difficulty breathing or acting really sick, Palmer says fevers that last less than three days can be managed at home.

At-home remedies for fevers

In addition to fever-reducing medications, Palmer suggests several steps you can take at home to keep your child comfortable while they have a fever:

  • Dress your little one in loose-fitting clothing without any extra layers.
  • Draw a lukewarm bath for your child. Bonus if you give them a popsicle for added hydration.
  • Offer extra fluids and soft, easy-to-eat foods. Your child might not have a strong appetite, but making sure they stay hydrated is important.
  • Extra snuggles can go a long way to helping your child feel better.

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