KidsMD Health Topics


  • Overview

    Your child has a fever if her temperature is 100.4 degrees Fahrenheit or higher.

    The body has several ways to maintain normal body temperature. 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
    • Naturally wanting to seek a cooler or warmer environment


    Boston Children's Hospital
    300 Longwood Avenue
    Boston MA 02115

  • In-Depth

    What causes a fever?

    When your child has a fever, her body works the same way to control the temperature but it resets its thermostat at a higher temperature. The temperature increases for a number of reasons:

    • Chemicals called cytokines or 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 combat 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.

    What conditions can cause a fever?

    The following conditions can cause a fever:

    What are the benefits of a fever?

    A fever actually helps the body destroy its microbial invader. It also stimulates an inflammatory response, which sends all kinds of substances to the area of infection to protect the area, prevent the spread of the invader, and start the healing process.

    What are the symptoms that my child may have a fever?

    Children with fevers may become more uncomfortable as the temperature rises. The following are the most common symptoms of a fever. However, each child may experience symptoms differently. In addition to a body temperature greater than 100.4 degrees Fahrenheit, symptoms may include:

    • Your child may not be as active or talkative as usual.
    • She may seem fussier, less hungry or thirstier.
    • Your child may feel warm or hot. Remember that even if your child feels like she is “burning up” the actual rectal or oral temperature may not be that high.

    The symptoms of a fever may resemble other medical conditions. According to the American Academy of Pediatrics, if your child is younger that two months of age and has a rectal temperature of 100.4 degrees Fahrenheit or higher, you should call your pediatrician. If you are unsure, always consult your child’s physician for a diagnosis.

  • When should a fever be treated?

    If your child is very uncomfortable, treatment may be necessary. Treating your child's fever will not help her body get rid of the infection any quicker, but it will relieve discomfort associated with it.

    Rarely, children between the ages of 6 months and 5 years can develop seizures from high fever (called febrile seizures). If your child does have a febrile seizure, there is a chance that the seizure may occur again, but, usually, children outgrow the febrile seizures. A febrile seizure does not mean your child has epilepsy.

    What can I do to decrease my child's fever?

    Give her an anti-fever medication, such as acetaminophen or ibuprofen. DO NOT give your child aspirin, as 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 her temperature to rise.
    • Encourage your child to drink plenty of fluids.
    • Give your child a lukewarm bath.
    • Place cold washcloths over areas of the body where the blood vessels are close to the surface of the skin such as the forehead, wrists and groin.

    When should I call my child's physician?

    If your child's temperature reaches 105 degrees Fahrenheit, this is considered a medical emergency and your child needs immediate medical attention, according to the American Academy of Pediatrics.

    Call your child's physician immediately if your child is younger than 3 months old and any of the following conditions are present:

    • Your child's rectal temperature is greater than 100.4 degrees Fahrenheit.
    • Your child is crying inconsolably.
    • Your child is difficult to awaken.
    • Your child's neck is stiff
    • Purple spots are present on the skin.
    • Breathing is difficult AND does not improve after you clear the nose.
    • Your child is unable to swallow anything and is drooling saliva.
    • Your child looks or acts very sick (if possible, check your child's appearance one hour after your child has taken an appropriate dose of acetaminophen.

    Call your child's physician within 24 hours if your child, 3 months or older, has any of the following conditions present:

    • The fever is 102 degrees Fahrenheit or higher (especially if your child is younger than 2 years old)
    • Burning or pain occurs with urination
    • Your child has had a fever for more than 24 hours without an obvious cause or location of infection.

    Call your child's physician during office hours if any of the following conditions are present:

    • Your child has had a fever more than 72 hours.
    • The fever went away for more than 24 hours and then returned.
    • Your child has a history of febrile seizures.
    • You have other concerns or questions.
  • Your Story

    I recently found myself in the Children’s Hospital Boston Emergency Room, waiting to have my toddler admitted for symptoms of pneumonia, including respiratory distress, high fever and hypoxia. From the get go, I attempted to keep my imagination in check and acknowledge that for all my son’s discomfort, we would most likely be walking out of the hospital, a little sleep deprived but none the worse for wear, in a matter of days.

    I had time to sit, think and observe, and it became clearly apparent that in its years of operation, Children’s has taken very seriously its responsibility to its patients and their families, soliciting and acting on feedback regarding how to make it the most comfortable experience possible. From the lively, engaging lobby with its ample seating, good food and entertaining displays, to the brightly lit floors with their happy visuals, the environment does a good job at masking the serious nature of one’s visit.

    While it broke my heart that some children are in-house long enough to merit individually painted windows in their rooms, I appreciated that they were allowed that little touch of humanity. Using small chunks of the hospital budget for things like stocked kitchens on the floors translate to big comfort and convenience for patients. When my son was taken off IV fluids and finally showed an interest in drinking again, it was a relief not to leave him alone at midnight, as there was some milk available a few doors down in the kitchen. The activity rooms on each floor, with their array of tops, books, movies and interactive projects, was a happy reminder of the fun things that childhood should be about.

    I hope I never have to have either of my children’s admitted to Children’s again, but should I need to, I’ll be completely confident that they’re in the best possible place. Thank you to all involved, for helping give parents that piece of mind.

    - Deidre Riley Thomson

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