Fever may be caused by infectious diseases, connective tissue diseases, blood system diseases and so on. 1. Infectious diseases: usually when bacteria, viruses, mycoplasma, parasites and other pathogens infect the human body, it may lead to the phenomenon that the patient’s fever goes down for a while. 2. Connective tissue diseases: such as rheumatic fever may also lead to the phenomenon of fever going down for a while. 3. Blood system diseases: If the patient suffers from leukemia, due to the reduction of white blood cells, the body’s defense ability will be reduced, which may also cause the patient to have a fever that recedes for a while. It is suggested that if the patient has recurrent fever, he should consult a doctor in time, and carry out standardized treatment after clarifying the cause of the disease.