How long fever-reducing medication lasts is generally how long a normal body temperature can be maintained after the fever-reducing medication has brought the body temperature down to normal, depending largely on the illness causing the fever. If the corresponding disease is mild, it is likely that the fever will not return in the future after the fever has subsided. If the inflammatory response is severe, or if the cause of the disease has not been fundamentally removed, the fever is likely to return. Generally, the effect of antipyretic drugs lasts for 4-6 hours. It is possible that a longer period of time for the reappearance of fever can reach a day, or even close to two days. However, if the corresponding inflammatory response is heavy, it is likely that the fever will reappear 1-2 hours after the fever has subsided. In clinical practice, it is even possible to see a fever reappear after a few minutes or tens of minutes after taking antipyretics to bring the temperature down to normal. In addition to using antipyretic drugs to reduce fever and relieve symptoms, it is important to find the cause and treat it.