Fever and its delayed resolution is considered to be the cause of fever that has not been removed. It may be related to germ infection, connective tissue disease, malignant tumor and other conditions, which need to be taken seriously and treated actively. 1. Pathogenic infection: If the pathogenic microorganisms in the body are not well eliminated, they will still be in a state of reproduction in the body and release some toxins to the body, which may lead to the symptoms of fever and delayed retreat. 2. Connective tissue diseases: systemic lupus erythematosus, rheumatoid arthritis and other connective tissue diseases, will trigger the human body to appear immunity decline, and at this time the body will also appear inside the inflammatory response, if the treatment is not appropriate, may lead to the patient has a fever and the phenomenon of delayed recession. 3. Malignant tumors: malignant tumors such as colon cancer and liver cancer may have metastasis, and if they metastasize to the brain, they may affect the central nervous system and cause central fever, and if the tumor factor in the head can not be removed, it may also lead to fever and delayed receding. If you have fever symptoms, do not use drugs on your own, you need to go to the hospital as soon as possible to check your health condition, identify the cause of the disease, and then carry out targeted treatment.