Fever occurs when the brain orders the body to raise its temperature in response to infection, injury, or other conditions. Just as your furnace works harder when you raise the thermostat setting in your home, the body shivers, the heart races, and the blood vessels constrict in an attempt to raise the body temperature. Fortunately for humanity, a healthy brain does not set the body's thermostat to dangerously high levels (or we would have been extinct long ago)!
Fever is different from hyperthermia. Hyperthermia is a dangerously elevated body temperature that is not under the body's control. Think of a fire in your house. This can happen in the person running 4 miles on a 100 degree day, or the infant wrapped in 4 blankets on a warm day.
When we deal with an infection, our concern is not the fever itself but the cause of fever. The following are conditions associated with fever requiring an immediate call to the physician.
1. Fever associated with change in mental status, stiff neck, severe headache, difficulty breathing, new rash, new limp, or signs of dehydration.
2. Any infant less than 2 months of age with fever 100.4 or higher.
3. Fever in a child who cannot adequately fight infection. Examples are children with diseases like cystic fibrosis, sickle cell disease, HIV, diabetes, and lupus. Also included are children on medications like chemotherapeutics and oral steroids (not inhaled).
4. Fever in a child who recently had surgery.
It is important to remember that treating fever does not treat the illness. We "treat" fever mainly for patient comfort. The best way to bring fever down is with an antipyretic medicine such as Acetaminophen (Tylenol) or Ibuprofen (Motrin), which lower the body's thermostat setting. Do not use Aspirin, as this can cause a dangerous brain and liver condition called Reye Syndrome. Cool or even room temperature baths are not a good idea because they only temporarily bring the temperature down without lowering the thermostat setting. Imagine leaving your doors open on a cold, blistery day. Your furnace will just work harder trying to get that temperature back up! Your child may feel like he/she is submerged in icewater.
Febrile seizures are seizures that occur only in the presence of fever. They occur in some susceptible children but are generally harmless (but very scary to the parent). Febrile seizures result from a rapid rise in temperature, and often times the seizure has begun by the time a parent recognizes the fever. It is advisable that your child be seen by a doctor the first time he/she has a seizure with fever just to make sure that it is in fact a febrile seizure and not another condition.