Fever is a physiologic response to infection or related stimuli (e.g. endotoxin, inflammation) such that the body temperature rises above normal. Fever is an attempt to fight off infection by making the body too hot for the invading microbe to function well in. Normal oral temperature being 36.3° C to 37.1° C or 97.3° to 98.8° F. The rectal temperature is about 0.5° C or 1° F higher than the oral temperature.