Health Topics A-to-Z

Fever

What Is It? A fever is an increase in body temperature above the normal range. However, body temperature varies between people, with different levels of activity and at different times of the day. Medical textbooks differ in their definition of the highest normal body temperature. Fever generally can be defined as an early morning temperature higher than 99 degrees Fahrenheit or a temperature higher than 100 degrees Fahrenheit at any time of the…

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