Fever Is Your Friend

Dr. Janesta Noland, one of the premiere pediatricians in the bay area, has agreed to share her expertise with us and to answer some of your questions on children's health issues.

Many parents fear that fever represents something dangerous happening in their child’s body. Could the child have a dangerous infection? Could the fever itself cause damage?

First, let’s talk about fever – what it is and what causes it. A fever is defined as temperature of 100.4F (38C) or greater taken rectally, 99.5F (37.5C) taken orally, or 99F (37.2C) taken under the arm. Fever happens when the body’s thermostat increases its set point. (Of note, children may sometimes develop increased body temperature when playing, but this is not fever because the set point is not elevated and the body will respond appropriately to return the temperature to normal.) Body temperature is controlled in the brain in a structure called the hypothalamus. Certain cytokines (cell activators) stimulate the hypothalamus to increase body temperature by increasing heat production via shivering or increased muscle tone and by preventing heat loss via constriction of blood vessels. External factors such as some parts of bacteria also act on the body to trigger fever.

Why does fever happen? Is it a disease? Fever was first identified as a symptom rather than a disease by a German physician in the 1800s. Fever is thought to make the body a more inhospitable place for invading organisms, some of which have strict temperature preferences. Fever also increases the effectiveness of white blood cells at fighting infection: they move more effectively, remove offending organisms more effectively and are less sensitive to toxic effects of invading organisms. Thus, fever may actually be desirable in helping rid the body of infection! Fever can be dangerous at extremely high temperatures, over 107F, but the primary downsides of fever are increased need for fluid and general discomfort. In young children (under 5 years), febrile seizures occasionally occur. Although frightening, these are not dangerous.

How can a parent know when to treat a child’s fever, or when to call a pediatrician? Here are general guidelines:
1) Any fever in an infant less than 8 weeks old should be brought to the attention of your pediatrician immediately.
2) Call your pediatrician if your child acts very ill, is not arousable, has a stiff neck or will not drink.
3) Signs of fever associated with a bacterial infection include stiff neck, pain on urination, or cough together with decreased energy. See your pediatrician if any of these signs occur.
4) Since both bacteria and viruses can cause fever, and since viruses are much more common, it is OK to observe your child if she is well-appearing when her temperature is down and is able to take in liquids. However, if the fever lasts more than 4 or 5 days (at which point most fevers caused by viruses go away), or if fever recurs after going away for a day or two, see your pediatrician to evaluate for a possible secondary bacterial infection.
5) If your child has a febrile seizure, call your pediatrician.

References: please see above links.