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Fever in Children

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All kids will develop fevers: Fevers in babies and children are common throughout childhood. Fevers are a natural response from the immune system to help fight an illness or infection.

Of course, as a parent, fevers in kids and babies can cause concern. Being informed about fevers and especially fever symptoms can help parents feel more prepared when their baby’s or child’s temperatures rise.

In this blog:

What is a fever? What temperature is considered a fever?

Fevers occur when the body temperature rises above normal. A temperature of 100.4°F (38°C) or higher is generally considered to be a “fever.” You may get slightly different readings depending on the type of the thermometer you’re using (for example, rectal versus forehead).

Fevers are often a sign the body is fighting an infection or illness. But your child may get fevers for other reasons, too. Babies may get fevers from being overdressed or in a hot environment because they can’t regulate their body temperature as well as older kids. Both babies and older children may also experience a mild fever after receiving a vaccine, which is normal. Babies who are teething may also have a slight rise in temperature, though usually not over 100°F.

Other (less common) causes of fever include:

  • Certain medications
  • Heat stroke
  • Blood transfusion
  • Disorders in the brain
  • Some kinds of cancer
  • Some autoimmune diseases

When is a fever too high?

Many parents wonder when they should seek medical attention. What’s “too high” depends on your child’s age:

  • For infants under 3 months old, a fever of 100.4°F (38°C) or higher requires immediate medical attention.
  • For babies 3 to 6 months old, a fever of 102°F (38.9°C) or higher warrants medical advice.
  • For a child over 6 months old, seek medical advice at 103°F (39.4°C) or higher.

Need a pediatrician?

  • Find a doctor

Normal body temperature

A normal body temperature is considered to be 98.6°F, but what’s normal for each person may be slightly lower or higher. Most people have a normal temperature between 97°F to 99°F. The type of thermometer you use may also affect the reading.

The body has several ways to maintain normal body temperature. The organs involved in helping with temperature regulation include the brain, skin, muscle and blood vessels. Your child’s body temperature may fluctuate with fevers or when the body responds to changes in temperature by:

  • Increasing or decreasing sweat production
  • Moving blood away from, or closer to, the surface of the skin
  • Getting rid of, or holding on to, water in the body
  • Seeking a cooler or warmer environment

What kind of thermometer should I use for babies and kids?

The best thermometer to use varies by your child’s age:

Age Rectal      Forehead Ear             Mouth     
Less than 3 months old ✓      
3-6 months old ✓ ✓    
6 months - 3 years old ✓ ✓ ✓  
Older than 3 years   ✓ ✓ ✓

Fevers in children: What causes temperatures to rise?

When your child has a fever, the body works the same way to control the temperature, but it temporarily resets its thermostat at a higher temperature. Baby fevers and kids fevers may show up or temperatures may increase for several reasons:

  • Chemicals, called cytokines and mediators, are produced in the body in response to an invasion from a microorganism, malignancy or other intruder.
  • The body is making more macrophages, which are cells that go to work when intruders are present in the body. These cells actually “eat up” the invading organism.
  • The body is busily trying to produce natural antibodies, which fight infection. These antibodies will recognize the infection next time it tries to invade.
  • Many bacteria are enclosed in an overcoat-like membrane. When this membrane is disrupted or broken, the contents that escape can be toxic to the body and stimulate the brain to raise the temperature. 

Some people believe you should “sweat” a fever to break it. Making your child sweat to break a fever won’t help; it will only add to their discomfort and may dehydrate them. Learn more about fever myths and facts.

When should a fever be treated?

In children, a fever that’s making them uncomfortable should be treated. Treating your child’s fever will not help the body get rid of an infection or illness any faster; it will simply relieve discomfort from the fever. Learn more about how to treat fevers with over-the-counter medications.

Call your child’s pediatrician about fevers if:

  • Your child is less than 3 months old and has a fever of 100.4°F (38°C) or higher
  • Your child is 3 to 6 months old and has a fever of 102°F (38.9°C) or higher
  • Your child is over 6 months old and has a fever of 103°F (39.4°C) or higher

Seek emergency care if your child has a fever and any of these symptoms:

  • Altered speech
  • Blue lips, tongue or nails
  • Continuous crying
  • Convulsions or seizures
  • Decreased urination
  • Dehydration
  • Difficulty breathing
  • Difficulty waking or extreme sleepiness
  • Excessive drooling or difficulty swallowing
  • Extreme sluggishness or drowsiness
  • Fever rash
  • Lack of appetite
  • Pain or tenderness in their abdomen
  • Redness or swelling
  • Stiff neck
  • Strange behavior

How can I lower my child’s fever?

For most kids, fever can be safely treated with acetaminophen or ibuprofen. If your child is 2 years old or younger, talk with your pediatrician before giving acetaminophen. Ibuprofen is safe for children 6 months and older.

DO NOT give your child or baby aspirin, as it has been linked to a serious, potentially fatal disease called Reye’s syndrome. Learn more about over-the-counter medications for fever.

Other ways to reduce a child’s fever:

  • Dress your child lightly. Excess clothing will trap body heat and cause the temperature to rise.
  • Encourage your child to drink plenty of fluids, such as water, juices, punch or popsicles.
  • Give your child a lukewarm bath. Don’t allow your child to shiver from cold water, as this can raise the body temperature. Never leave your child unattended in the bathtub.

Frequently asked questions about fevers in kids and babies

Fever is usually a sign that your body is fighting an illness or infection. Fever stimulates the body’s defenses, sending white blood cells and other “fighter” cells to fight and destroy the cause of the infection. When a child has a fever, it’s harder for bacteria and viruses to survive.

Fevers can be temporary or may require medical attention depending on the individual and cause. Fevers can come and go quickly or may take some time to come back to normal.

Children with fevers may become more uncomfortable as the temperature rises. Each child may experience fever symptoms differently. In addition to an elevated body temperature, your child may:

  • Not be as active or talkative
  • Seem fussier, less hungry and thirstier
  • Feel warm or hot with a fever — remember that even if your child feels like they are “burning up,” the measured temperature may not be that high

Call your child’s pediatrician if:

  • Your child is 2 years old or younger, and the fever persists for more than 24 hours. 
  • Your child is older than 2 and has had a fever more than 72 hours.
  • Your child seems to be getting worse or still acts sick when the fever comes down. 
  • You have other concerns or questions or are worried about your child’s fever.

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