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Myths and Facts about Fever

Misconceptions about the dangers of fever are commonplace. Unwarranted fears about harmful side effects from fever cause lost sleep and unnecessary stress for many parents. Let the following facts help you put fever into perspective:

MYTH: All fevers are bad for children.

FACT: Fevers turn on the body's immune system. Fevers are one of the body's protective mechanisms.

Most fevers are good for children and help the body fight infection. Use the following definitions to help put your child's level of fever into perspective:


       100F to 102F     Low-grade fever: Beneficial. Try 
       (37.8C to 39C)   to keep the fever in this range.  

       102F to 104F     Moderate-grade fever: Beneficial. 
       (39C to 40C) 

       Over 104F         High fever: Causes discomfort, but 
       (40C)             is harmless. 

       Over 105F         High fever: Higher risk of 
       (40.6C)           bacterial infections. 

       Over 108F         Serious fever:  The fever itself can 
       (42C)             be harmful. 

MYTH: Fevers cause brain damage or fevers over 104F (40C) are dangerous.

FACT: Fevers with infections don't cause brain damage. Only body temperatures over 108F (42C) can cause brain damage. The body temperature goes this high only with high environmental temperatures (for example, if a child is confined in a closed car in hot weather).

MYTH: Anyone can have a febrile seizure (seizure triggered by fever).

FACT: Only 4% of children have a febrile seizures.

MYTH: Febrile seizures are harmful.

FACT: Febrile seizures are scary to watch, but they usually stop within 5 minutes. They cause no permanent harm. Children who have had febrile seizures do not have a greater risk for developmental delays, learning disabilities, or seizures without fever.

MYTH: All fevers need to be treated with fever medicine.

FACT: Fevers need to be treated only if they cause discomfort. Usually that means fevers over 102F or 103F (39C or 39.4C).

MYTH: Without treatment, fevers will keep going higher.

FACT: Wrong. Because of the brain's thermostat, fevers from infection top out at 105F or 106F (40.6C or 41.1C) or lower.

MYTH: With treatment, fevers should come down to normal.

FACT: With treatment, fevers usually come down 2 or 3F (1.1 or 1.7C).

MYTH: If the fever doesn't come down (if you can't "break the fever"), the cause is serious.

FACT: Fevers that don't respond to fever medicine can be caused by viruses or bacteria. Whether the medicine works or not doesn't relate to the seriousness of the infection.

MYTH: If the fever is high, the cause is serious.

FACT: If the fever is high, the cause may or may not be serious. If your child looks very sick, the cause is more likely to be serious.

MYTH: The exact number of the temperature is very important.

FACT: How your child looks is what's important, not the exact temperature.

MYTH: Temperatures between 98.7F and 100F (37.1C to 37.8C) are low-grade fevers.

FACT: The normal temperature changes throughout the day. It peaks in the late afternoon and evening. A low-grade fever is 100F to 102F (37.8C to 39C).

Reading Temperatures

  • A reading of 99.4F (37.4C) is the average rectal temperature. It normally can change from 98.4F (36.9C) in the morning to a high of 100.3F (37.9C) in the late afternoon.
  • A reading of 98.6F (37C) is just the average oral temperature. It normally can change from a low of 97.6F (36.4C) in the morning to a high of 99.5F (37.5C) in the late afternoon.
Written by B.D. Schmitt, M.D., author of "Your Child's Health," Bantam Books.
Published by McKesson Provider Technologies.
Last modified: 2002-01-07
Last reviewed: 2006-03-02
This content is reviewed periodically and is subject to change as new health information becomes available. The information is intended to inform and educate and is not a replacement for medical evaluation, advice, diagnosis or treatment by a healthcare professional.
Copyright 2006 McKesson Corporation and/or one of its subsidiaries. All Rights Reserved.
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