A fever of 39.4 degrees Celsius that does not go down after taking ibuprofen for two hours is usually associated with infectious fever, connective tissue diseases and tumors, and requires general treatment, medication or surgery depending on the cause. 1. Infectious fever: for example, bacterial infection, viral infection, parasitic infection, etc., may cause fever. Fever reducers alone are not effective, so when a fever of 39.4 degrees Celsius does not go down after two hours of ibuprofen, it is usually treated with a combination of antibacterial and antiviral drugs, such as cefradine capsules and ribavirin granules, and oral albendazole tablets are needed to treat parasitic infections. 2. Connective tissue diseases: such as rheumatism, rheumatoid diseases, arthritis, dry syndrome, etc., may cause fever, in the oral antipyretic drugs at the same time, should be combined with dexamethasone, methylprednisolone injection to fight infection. 3. Tumor: such as liver cancer, lung cancer, lymphoma and so on, the fever caused by these diseases belongs to cancer fever, the effect of simply taking antipyretic drugs is not ideal, so we should treat the primary disease as soon as possible. If the tumor is in the early stage, surgery can be done to remove the tumor, and patients in the middle or late stage can be treated with radiotherapy to inhibit the cancer cells. If the fever persists for several days and does not go down, it is necessary to consult a doctor and go through relevant examinations to understand the cause of the disease and then carry out regular treatment.