What is fever?
Fever is the body's reaction to infection. Fever works to defend the body against infection, since most germs can't grow well at higher body temperatures and some parts of the immune system work better at higher temperatures.
When the body has reset its thermostat, any temperature below that is considered by the body to be cold; so if, for example, the thermostat has been reset to 104 F, a temperature of 102 F will actually seem cold, and the body starts shivering to increase body heat; that's why we get "chills."
While fever is considered a rise in body temperature, not everyone's body temperature is the same. The common average cited is 98.6 F, but your actual "normal" temperature may vary. In children, fever is regarded as anything 100 F or higher. (Note: this number may vary slightly with different doctors.) It used to be common to say that the rectal temperature was one degree higher than oral, and axillary (underarm) was one degree less than oral, but that turns out to be not true all the time; it can vary from half a degree to 2 degrees difference.
How should I take a temperature in my child?
Rectal and oral temperatures are considered more accurate than axillary temperatures. We recommend rectal temperatures for infants.
The best way for taking temperatures used to be the glass thermometer, but these have disappeared due to other styles of thermometers. The digital thermometer (it looks like a standard thermometer but has a digital readout) is a very good. The forehead strips are very unreliable; you're better off guessing than using these. There is a device consisting of a pacifier with a thermometer, but the infants have to suck continuously for 3 to 5 minutes for it to work, which is unlikely. Finally, infra-red technology has made the "ear thermometer" useful; unfortunately, they do not work well in newborns and other infants with small ear canals. Also, they become fairly inaccurate at temperatures over 104 F, often reading higher than the temperature really is. The newest thermometer is the temporal thermometer, which reads from the forehead and the temple area. This is accurate but may also take a while to learn to use correctly.
Is fever dangerous?
Despite what you may have heard, fever is not dangerous to your child. The amount of temperature required to hurt the human brain is over 107.6 F. Fever due to infection very rarely goes over 106.0, and while scary to parents, is not harmful. (Temperatures over 107 F are usually due to heatstroke, head trauma, toxic ingestions or anesthesia side effects.) Seizures due to fever can occur in the age range of 4 months to 6 years, but is most often associated with an abrupt rise in temperature, not an extremely high fever. And while seizures due to fever are frightening, they are short (less than 5 minutes) and are very rarely harmful to the child's brain.
Treating a fever
The reason for treating the fever, then, is to make the child feel better. Certainly the higher the fever goes, the worse the child feels. One medicine you can use is acetaminophen (Tylenol) every 4 hours; it can be given orally or rectally. Ibuprofen (Motrin, Advil) appears to be slightly better at decreasing fevers over 103 F, and is given every 6 hours. Aspirin is NOT recommended for children under 18 years of age due to the risk of Reyes syndrome, which is a liver disease associated with the use of aspirin and certain viral infections.
Many parents ask us about alternating ibuprofen and acetaminophen for better fever control. We do not recommend doing this routinely since we are not concerned about fever hurting your child. However, if you are using ibuprofen every 6 hours and your child is still miserable due to fever between doses, then occasional doses of acetaminophen can be useful to help him or her feel better. If you decide to use both medications, it's a good idea to write down what you give and when so you don't accidentally give too much of one of the medications. It's also a good idea to write the doses down if more than one parent is giving medications to avoid overdoses.
While waiting for the medicine to take effect, the temperature can also be brought down by lukewarm water baths. Cold water or ice water is not recommended as they can cause the blood vessels in the skin to constrict, and decrease the body's ability to get rid of extra heat. Also, cold or icy water will cause the child to shiver, which will increase the body's internal heat. Do not use alcohol baths, since there is a small risk of alcohol poisoning.
When to contact us
Remember, fever is a sign of infection or inflammation. If the source of the fever is not obvious within a day or two, it's a good idea to have your child examined by one of us during office hours.
A special note about fever in babies 3 months of age and younger: these infants tend not to show any difference between mild infections and serious infections. In this special case, we want you to notify us as soon as possible regarding the fever.