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Fever and Your Baby

When your baby has a fever, especially if it's their first one, it can be alarming. Keep in mind that fever, which is sign or symptom of illness, is usually a good sign that the body is fighting off an infection. But it's important to figure out the cause of your baby's fever so it can be treated, and to help keep your child hydrated and comfortable.

What's considered a fever?

A child's normal temperature can vary, depending on age and activity level. Time of day can also affect the reading. Body temperature is highest in the late afternoon and early evening, for example, and lowest at night and early morning. Plus, infants tend to have higher temperatures than older children. Generally, these are considered true fevers:

  • Rectal reading of above 100.4 degrees Fahrenheit (38 degrees Celsius)

  • Oral reading of above 99 degrees Fahrenheit (37.2 degrees Celsius)

How do I know if my baby has a fever?

Whenever you think your child has a fever, take their temperature with a thermometer. Feeling their forehead or other parts of the body is not accurate, especially if your baby is having chills. Using temperature sensitive tape or "fever strips" also is not reliable. Avoid using an ear thermometer for babies under 6 months old, since their ear canals are too small to allow an accurate reading.

Causes of fever in babies

Fever in babies can develop with illnesses such as:

The most serious conditions that can cause fever are infections blood (sepsis) and the brain and spinal cord (meningitis).

Fever in newborns

Infants younger than two months old who have a fever need immediate medical attention, even if they appear well and show no other signs of being ill. The challenge is to find the cause of the fever quickly while avoiding putting the baby through unnecessary tests or hospitalizations.

About 10% of young infants with fever are found to have urinary tract infections. The rate is even higher in uncircumcised boys. That's why having a urine sample checked is important. However, young infants can have more serious underlying infections that can rapidly progress. If your newborn develops a fever, contact your health care provider, without delay, and discuss steps needed to evaluate and treat your baby.

Febrile convulsions

In children between 6 months old and five years of age, fever can trigger seizures. These are called febrile convulsions. A child may get an odd look on their face for a few moments, then stiffen or twitch, roll their eyes, and become unresponsive for a short time. Febrile convulsions typically last less than a minute—or even just a few seconds--though it can seem forever to a frightened parent. Thankfully, febrile convulsions are not common and almost always are harmless, causing no lasting damage to the brain or nervous system. However, if your baby has a febrile convulsion, be sure to tell your pediatrician promptly.

Raised body temperature from heatstroke

Fever should not be confused with heat-related illness, or heatstroke. This is not caused by infection. Instead, this dangerous condition is caused by surrounding heat in their environment and dehydration. With heatstroke, body temperature can rise to dangerous levels (above 105 degrees Fahrenheit [40.5 degrees Celsius]). Dozens of children die each year when left unattended in closed, overheated cars, for example. Never leave your baby alone in closed car, even for a few minutes. Babies can also develop heatstroke if overdressed in hot, humid weather.

If you think your child has heatstroke, call 911 or go to the emergency department right away.

Does teething cause fever?

Teething, which often starts at about 6 months of age, can cause a slight rise in your baby's body temperature within the normal range. However, research shows teething does not cause a true fever.

More information

Last Updated
Adapted from Caring for Your Baby and Young Child: Birth to Age Five 7th edition (Copyright © 2019 American Academy of Pediatrics)
The information contained on this Web site should not be used as a substitute for the medical care and advice of your pediatrician. There may be variations in treatment that your pediatrician may recommend based on individual facts and circumstances.
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