Paracetamol is the active metabolite of phenacetin
and has analgesic and antipyretic properties.1 It
is a cyclooxygenase-3 inhibitor within the central
nervous system and it is thought to exert
an antipyretic effect through an inhibition of
prostaglandin synthesis and resultant effects on
resetting the thermoregulatory set-point.Thermoregulation
maintains core body temperature
within a narrow normal range despite changes
in environmental conditions. This is achieved by
balancing heat production and heat loss to the environment.
Heat loss to the environment is primarily
controlled by behavioural responses and controlling
heat loss from skin.Heat dissipation can either
be increased or decreased as required by respectively
increasing or decreasing skin blood flow
(skBF).Heat dissipation can also be increased
dramatically through sweating and the heat loss
associated with the latent heat of vaporisation. A
rise in body temperature is affected by increased
heat production (shivering, increased metabolic
rate) coupled with a decrease in heat loss that
occurs with vasoconstriction of cutaneous blood
vessels and a reduction in skBF.