Fever is an important part of the body's defense against infection. Most bacteria and viruses that cause infections in humans thrive best at 98.6°F (37°C). Raising the body temperature a few degrees can help the body fight the infection. In addition, a fever activates the body's immune system to make more white blood cells, antibodies, and other infection-fighting agents.
Reviewed By: Frank D. Brodkey, MD, FCCM, Associate Professor, Section of Pulmonary and Critical Care Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.