Fever in Children
What is a fever?
Most healthcare providers define a fever as a temperature of 100.4°F (38°C) or higher
when taken rectally or 100°F (37.8°C) or higher when taken by mouth. You might get
slightly different numbers depending on how you take your child's temperature.
The body has several ways to maintain normal body temperature. The organs that help
regulate temperature include the brain, skin, muscle, and blood vessels. 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
When your child has a fever, the body works the same way to control the temperature.
But it has temporarily reset its thermostat at a higher temperature. The temperature
increases for these reasons:
The body is making certain chemicals called cytokines and mediators. These are made
in response to an invasion from a microorganism, malignancy, or other intruder.
The body is making more macrophages. These are cells that fight when intruders are
present in the body. These cells actually "eat up" the invading organism.
The body is busy trying to make 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 come out can be toxic to the body. They cause the brain
to raise the temperature.
What conditions can cause a fever?
These conditions can cause a fever:
What are the benefits of a fever?
Fever is not an illness. It is a symptom, or sign, that your body is fighting an illness
or infection. Fever stimulates the body's defenses. White blood cells and other "fighter"
cells are sent out to fight and destroy the cause of the infection.
What are the symptoms that my child may have a fever?
Children with fevers may become more uncomfortable as the temperature rises. Along
with a body temperature greater than 100.4°F (38°C), symptoms may include:
Your child may not be as active or talkative as usual.
Your child may seem fussier, less hungry, and thirstier.
Your child may feel warm or hot. Remember, even if your child feels like they are
"burning up," the measured temperature may not be that high.
The symptoms of a fever may look like other health problems. If you are unsure, always check
with your child's healthcare provider for a diagnosis.
How should I check my child's temperature?
Use a digital thermometer to check your child’s temperature. Don’t use a mercury thermometer.
There are different kinds and uses of digital thermometers. They include:
Rectal. For children younger than 3 years, a rectal temperature is the most accurate.
Forehead (temporal). This works for children age 3 months and older. If a child under 3 months old has
signs of illness, this can be used for a first pass. The provider may want to confirm
with a rectal temperature.
Ear (tympanic). Ear temperatures are accurate after 6 months of age, but not before.
Armpit (axillary). This is the least reliable but may be used for a first pass to check a child of any
age with signs of illness. The provider may want to confirm with a rectal temperature.
Mouth (oral). Don’t use a thermometer in your child’s mouth until they are at least 4 years old.
Use a rectal thermometer with care. Follow the product maker’s directions for correct
use. Insert it gently. Label it and make sure it’s not used in the mouth. It may pass
on germs from the stool. If you don’t feel OK using a rectal thermometer, ask the
healthcare provider what type to use instead. When you talk with any healthcare provider
about your child’s fever, tell them which type you used.
Below is when to call the healthcare provider if your child has a fever. Your child’s
healthcare provider may give you different numbers. Follow their instructions.
When to call a healthcare provider about your child’s fever
For a baby under 3 months old:
First, ask your child’s healthcare provider how you should take the temperature.
Rectal or forehead: 100.4°F (38°C) or higher
Armpit: 99°F (37.2°C) or higher
A fever of ___________as advised by the provider
For a child age 3 months to 36 months (3 years):
Rectal or forehead: 102°F (38.9°C) or higher
Ear (only for use over age 6 months): 102°F (38.9°C) or higher
A fever of ___________ as advised by the provider
In these cases:
Armpit temperature of 103°F (39.4°C) or higher in a child of any age
Temperature of 104°F (40°C) or higher in a child of any age
A fever of ___________ as advised by the provider
When should a fever be treated?
In children, a fever that is making them uncomfortable should be treated. Treating
your child's fever will ease discomfort linked to the fever. It will not help the
body get rid of the infection any faster. It will also not reduce the risk of your
child having a seizure from the fever (called a febrile seizure).
Children between the ages of 6 months and 5 years can develop febrile seizures. If
your child does have a febrile seizure, there is a chance that the seizure may occur
again. A febrile seizure does not mean your child has epilepsy. That is a seizure
disorder not triggered by a fever. But, depending upon how often febrile seizures
occur and how long they last, a very small number of children develop epilepsy in
What can I do to decrease my child's fever?
Give your child an antifever medicine, such as acetaminophen or ibuprofen. Don't give your child aspirin. It has been linked to a serious, potentially fatal disease,
called Reye syndrome.
Other ways to reduce a fever:
Dress your child lightly. Excess clothing will trap body heat and cause the temperature
Encourage your child to drink plenty of fluids, such as water, juices, or popsicles.
Give your child a lukewarm bath. Do not allow your child to shiver from cold water.
It can raise the body temperature. Never leave your child unattended in the bathtub.
Don'tuse alcohol baths.