Normally, after a patient takes a fever-reducing medicine, the effect of the medicine starts to work after half an hour, and then the body temperature may return to normal in about an hour. However, the effect of antipyretic drugs varies from person to person for different drugs and different patients’ body types. Commonly used clinical antipyretic drugs include ibuprofen extended-release capsules and acetaminophen, which are relatively safe and have a more stable effect and are also suitable for pediatric patients. For patients with fever, it is recommended that they do not take one antipyretic drug all the time. For example, if acetaminophen is used for 4 hours and the patient’s temperature does not drop significantly, it is recommended to switch to ibuprofen extended-release capsules. This will increase the metabolic rate of the drug in the body and reduce the damage to the liver and kidneys. It should be noted that it is not recommended to use antipyretic drugs again within 4 hours of taking antipyretic drugs. If there is little change in the patient’s temperature after 4 hours of taking antipyretic medication, it is best to go to the hospital, especially for some patients in pediatrics, because persistent high fever is likely to lead to febrile convulsions. The patient’s fever usually subsides within an hour or so after taking antipyretic medication, but there are cases where the fever does not subside after taking antipyretic medication. For unexplained fever, it is best to see a doctor promptly to avoid blind use of antipyretic drugs.