Fever

Fever is defined as a body temperature higher than the normal core temperature of 100F (37.8C). It is a sign of a regulated increase in the body’s thermoregulatory set-point in response to a pyrogen. Fever is differentiated from hyperthermia, which represents a malfunctioning of the normal thermoregulatory process at the hypothalamic level, and hyperpyrexia, a body temperature greater than 106F (41.1C) that typically results in harmful mental and physical consequences.

Fever is a symptom – an indication of an underlying process. It is not inherently harmful; in fact, there is evidence that fever is an adaptive response and that elevated body temperature may be beneficial. The principal reason for treating fever is to alleviate patient discomfort. Therefore, the decision to treat fever should be based on a patient-specific risk-benefit ratio. Arguments against treating fever include the generally benign and self-limited course of fever, the possible elimination of a diagnostic or prognostic sign, the attenuation of enhanced host defenses (possible therapeutic effect of fever), and possible untoward effects of antipyretic medications.

No correlation exists between the magnitude and pattern of temperature elevation (i.e., persistent, intermittent, recurrent, or prolonged) and the principal etiology or severity of the underlying pathology. Because it is difficult to determine the cause of the fever on the sole basis of the temperature reading, investigation into the underlying cause is important. In some instances, fever may indicate a serious condition (eg, acute infectious process) that requires prompt medical evaluation.