Fever once the ibuprofen has worn off may be the result of a failure to control the primary illness causing the fever, causing the patient to experience recurrent fever symptoms. Normally, ibuprofen has an antipyretic effect for a certain period of time and is mainly used to control the symptom of fever. Usually half an hour to an hour after taking the drug will work to reduce fever, it can be maintained in the body for about 4 to 6 hours. After more than 4~6 hours, it is basically eliminated gradually in the body, and the antipyretic effect also gradually subsides. If the primary disease factors causing fever are not controlled at this time, the patient will have the symptom of recurring fever. Repeated fever may be caused by pneumonia, respiratory tract infections, etc. It is recommended that the patient go to the hospital in time to clarify the specific cause of the disease and then follow the doctor’s instructions for the control of the primary disease treatment, in order to alleviate the fever fundamentally.