Usually the fever is reduced in half an hour to one hour after taking the fever-reducing medicine. Ibuprofen is also the same, and the fever-reducing effect of ibuprofen is relatively fast, taking ibuprofen usually takes effect in 10 minutes, and the fever will be significantly reduced in about half an hour. However, it is important to emphasize that you should only take ibuprofen when your body temperature is above 38.5°C and not more than 4 times a day. The fever-reducing medicine itself does not target the cause of the inflammation, so the fever may return even if the cause has not subsided. Therefore, it is best to go to the hospital to further examine the cause of the fever even after the fever has subsided, because only when the cause is solved will there be no recurrence of fever.