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BACKGROUND
Surveys in the UK and the USA, for example, suggest that many parents have a very poor understanding of normal body temperature and fever. 3 - 5 When their child is unwell, they may worry about fever rising inexorably and causing harm, including fits, brain damage or even death. They may also continuously assess a sick child's temperature and perform cooling procedures. 3 - 5 A UK survey found that parents commonly use antipyretic drugs and sponging to treat children with fever. 4 Some parents will even awaken their child at night to administer antipyretics in an attempt to control a fever. 4
Similarly, the immediate reaction of many healthcare professionals is to attempt to reduce any fever in a child.
ABOUT FEVER
What is fever?
Fever involves a rise in body temperature due to an increase in the thermostatic set-point in the hypothalamus. This change activates thermoregulatory mechanisms, including re-direction of blood flow from cutaneous to deep vascular beds to minimise heat loss through the skin, decreased sweating, onset of shivering and seeking of a warmer environment.
Fever may be accompanied by other symptoms, including pain and reduced activity. It is not always clear whether these accompanying features are the direct result of the fever itself, or of the underlying illness, or a combination of the two.
Difficulties in defining fever
Measured body temperature varies depending where on the body it is taken and the type of thermometer used; also, normal body temperature has a diurnal variation of about 0.5°C. These variables make it difficult to define fever. For example, it has been variously defined as a temperature of 37.5°C or more (axillary) or 38°C or more (core body temperature) 6 or as "an elevation of body temperature above normal daily variation". 1
Distinguishing fever from hyperthermia
The regulated rise in body temperature which occurs in fever is very different from hyperthermia. Hyperthermia is an unregulated rise in core temperature to a level above the hypothalamic set-point; it may result either from over-production of heat (e.g. as a result of a thyroid storm), or a reduced ability to lose heat (e.g. as in an over-dressed baby), or a combination of the two (as with heat stroke from overexertion in a hot environment)....