According to the characteristics of fever, fever can be divided into fever rising period, high fever persistence period and fever falling period. In the rising fever period, heat production increases, heat dissipation decreases, heat production is greater than heat dissipation, and body temperature rises rapidly or gradually. When the body temperature rises to a level appropriate to the new tuning point level, the heat production and heat dissipation fluctuate at a higher level, which is called the hyperthermia persistence period. As the fever activator is controlled or disappears in the body, the rising body temperature regulating point drops back to normal level. Since the level of the tuning point is lower than the body temperature at the time of fever, a cooling command is sent from the hypothalamus, which not only causes vasodilation of the skin, but also causes profuse sweating, called the period of fever descent.