What is body temperature?

The normal body temperature of a person varies depending on gender, recent activity, food and fluid consumption, time of day, and, in women, the stage of the menstrual cycle. Normal body temperature, according to the American Medical Association, can range from 97.8°F (or Fahrenheit, equivalent to 36.5° C, or Celsius) to 99° F (37.2° C). A person's body temperature can be taken in any of the following ways:

What is fever?

Fever (also called pyrexia) is defined as body temperature that is higher than normal for each individual. It generally indicates that there is an abnormal process going on within the body. The severity of a condition is not necessarily reflected by the degree of fever. For example, influenza may cause a fever of 104° F, while pneumonia may cause a very low-grade fever or no fever at all. Consult with your physician if you have any questions about whether a fever is significant.

• orally
  Temperature can be taken by mouth using either the classic glass thermometer or the more modern digital thermometers that use an electronic probe to measure body temperature.
• rectally
  Temperatures taken rectally (using a glass or digital thermometer) tend to be 0.5 to 0.7° (Fahrenheit) higher than when taken by mouth.
• axillary
  Temperatures can be taken under the arm using a glass or digital thermometer. Temperatures taken by this route tend to be 0.3 to 0.4° (Fahrenheit) lower than those temperatures taken by mouth.
• by ear
  A special thermometer can quickly measure the temperature of the ear drum, which reflects the body's core temperature (the temperature of the internal organs).

Body temperature may be abnormal due to fever (high temperature) or hypothermia (low temperature). A fever is indicated when body temperature rises above 98.6° F orally or 99.8° F rectally, according to the American Medical Association. Hypothermia is defined as a drop in body temperature below 95° F.