Fever that does not go down after taking ibuprofen may be caused by a short period of time after taking the medicine and unresolved primary illness. If the fever persists, you need to go to the hospital for treatment. 1. The fever does not go down after taking ibuprofen may be due to a shorter period of time after taking the medicine. Ibuprofen is a kind of antipyretic and analgesic drugs, can through the thermoregulatory center to achieve the purpose of antipyretic, generally in the drug half an hour to an hour later, can take effect. If you don’t see a decrease in body temperature after taking the medication, it may be caused by the short duration of the medication and you need to wait patiently for the medication to take effect. 2. If the fever does not go down after taking ibuprofen, it may be due to unresolved primary illness. Ibuprofen can be used to treat fever caused by the common cold or influenza, if you do not see any improvement after taking the drug, the patient’s fever may be caused by other reasons, such as bacterial infections, intracranial lesions, etc., the primary disease has not been resolved, it is difficult to return to normal body temperature. If the patient’s fever persists and the temperature keeps rising, he/she needs to go to the hospital for treatment in time.