How High Is Too High When It Comes to Fever in Children?

Content medically reviewed by Aubrey DeCoteau, APRN, CNP

Your child feels hotter than normal, and you’re wondering and worrying that it’s something serious. Take a deep breath: Most of the time, fever in children isn’t a cause for concern.

In fact, many times when your child feels a little hot, they may not even actually have a fever. A fever in children is defined as a temperature of 100.4 F or higher when measured rectally, in the ear, or on the forehead; 99.5 F when measured orally; or 99 F when measured under the arm.

Even if your child’s temperature reaches that threshold, you can probably take care of them in the comfort of your home. Keep reading as we offer some insight about whether a fever should be treated at all, when it can be treated at home, and when to call your child’s provider.

The Facts About Fevers

While a child’s fever can be scary for parents, fevers aren’t a bad thing. They’re a function of the immune system jumping into action.

“When your child is exposed to a virus or bacteria, the immune system revs up to get rid of the infection, causing a chain of reactions throughout the body,” said Aubrey DeCoteau, a certified pediatric nurse practitioner at Essentia Health. “A fever is one of those reactions.”

Most bacteria and viruses thrive at the body’s “normal” temperature of approximately 98.6 F. By raising your child’s body temperature temporarily, the immune system works to make the body less hospitable to the infection. A higher temperature also causes the immune system to produce more white blood cells and antibodies, which fight infection.

Many different conditions can cause a fever, including viruses and bacterial infections such as strep throat, COVID-19, the flu, and respiratory syncytial virus (RSV). A higher-than-normal temperature isn’t always caused by an illness: Physical activity, emotions, heavy clothing, certain medications, and the outside temperature and humidity level can all increase body temperature.

How to Bring a Child’s Fever Down

What should you do if your child has a fever? According to the American Academy of Pediatrics (AAP), you don’t usually need to treat a fever unless your child is uncomfortable.

If your child is eating, drinking, and behaving normally but has a fever, the main issue is simply the higher temperature of your child’s body. Do your best to keep them comfortable by suggesting they wear lighter clothing, encouraging them to drink plenty of fluids, allowing them to rest, and keeping the room temperature cool.

If your child has a fever and other symptoms, such as a headache or body aches, you can use over-the-counter fever reducers such as acetaminophen or ibuprofen to lower their temperature and ease discomfort. Be sure to carefully follow the dosage guidelines on the package or provided by your child’s care provider. Never give your child aspirin, which can cause severe side effects including a potentially fatal disease called Reye syndrome.

If you bathe your child, keep the water temperature warm. While it might seem like bathing your child in cool or cold water can cool them down, it can actually increase body temperature by causing shivering.

When to Take Your Child to the Doctor for a Fever

While many fevers can be treated at home, medical attention is needed in some cases.

While a mild fever doesn’t usually require treatment in older children, that’s not the case for infants. If your child is younger than 3 months of age, contact their provider’s office any time they have a temperature of 100.4 F or higher. You can contact your provider’s office via phone, through a MyChart message, or you can call the nurse care line.

“For children of all ages, you also should contact their care provider if their fever reaches 104 F repeatedly—meaning it increases again after Tylenol or Motrin wears off or lasts longer than 24–48 hours,” DeCoteau said.

Even if your child’s fever doesn’t hit that mark, call their provider if the fever lingers for longer than 24 to 48 hours in children younger than age 2 or longer than 72 hours in older children. While it may still not be cause for concern, it’s best to get a medical provider’s thoughts on what you should do next.

The AAP also recommends seeking medical attention if your child has a fever and they –

• Have had a seizure during this fever
• Have heart problems that affect heat tolerance
• Have immune system problems or take medications that impair the immune system
• Have other symptoms, such as severe headache, a stiff neck, breathing difficulty, or an unexplained rash
• Seem very sick or unusually drowsy or hard to wake up
• Were in an overheated car or another very hot environment

Your child’s provider may offer you guidance for how to care for their fever over the phone, or they may have you bring your child to the office. During an appointment, the provider may recommend running tests to determine what’s causing the fever and offer suggestions for treating the underlying cause of the fever and the fever itself.