A child with fever followed by symptoms of hot and cold is considered to have a fluctuating fever. Possible causes include abnormal thermoregulation, drug effects, and other causes. High fever due to sepsis, rheumatic fever, septic inflammation, etc., usually has a large amplitude of fluctuation, which is manifested as a fall in body temperature of more than 2 ℃ in one day. This cause may on the one hand be related to the abnormal function of the thermoregulatory center in pathological states. On the other hand, since antipyretic drugs are usually used in hyperthermia, both heat and drugs have their own time limit, and fluctuations in the effects of the drugs may also cause recurrence of body temperature. The most important measure for this abnormal temperature phenomenon is the treatment of the original disease, and the common clinical treatment includes the use of penicillin and other medications for infections. Usually after treatment, the fluctuation of body temperature will disappear; the emergence of fever combined with fluctuation of temperature, it is recommended to consult a doctor in time; the above mentioned penicillin and other drugs should be used under the guidance of clinicians.