The effect of antipyretic injection will be seen in about 30-60 minutes, and the specific time to reduce fever is related to the individual’s condition. Usually the body temperature will gradually drop after 30-60 minutes of intramuscular injection of antipyretic injection, but the specific time to reduce fever is closely related to each person’s constitution and condition, for example, the onset of action of antipyretic injection in children with imperfectly developed nerve centers will be appropriately prolonged, and it usually takes 1 hour to take effect after the initial injection of antipyretic injection, while it may take 30 minutes to reduce fever during the peak of fever. In addition, intravenous injections will have a faster onset of action than intramuscular injections, while for fever due to pyrexia or cerebral hemorrhage, fever reduction injections may not be effective. In addition, the patient can also be physically cooled after the fever shot, and the cause of the fever should be actively sought and then treated for the original cause.