Fever is the temporary increase in the body's temperature in response to some disease or illness.

A child has a fever when the temperature is at or above one of these levels:

• 100.4 °F (38 °C) measured in the bottom (rectally)
• 99.5 °F(37.5 °C) measured in the mouth (orally)
• 99 °F (37.2 °C) measured under the arm (axillary)

An adult probably has a fever when the temperature is above 99 - 99.5 °F (37.2 - 37.5 °C), depending on the time of day.

See also:

• Heat emergencies
• Temperature measurement

Elevated temperature; Hyperthermia; Pyrexia

Normal body temperature may change during any given day. It is usually highest in the evening. Other factors that may affect body temperature are:

• In the second part of a woman's menstrual cycle, her temperature may go up by 1 degree or more.
• Physical activity, strong emotion, eating, heavy clothing, medications, high room temperature, and high humidity can all increase your body temperature.

Images

Thermometer temperature

Temperature measurement

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Fever Treatment

Review Date: 01/29/2010
Reviewed By: Neil K. Kaneshiro, MD, MHA, Clinical Assistant Professor of Pediatrics, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org)