Fever is a common symptom of tumor patients. There are many causes of fever, and corresponding treatment should be given after the causes of fever are clarified. Common conditions include tumor fever, infection and brain metastasis, etc.: 1. Tumor fever: tumor cells can secrete a large amount of tumor necrosis factor, interleukin, interferon, etc., which can cause fever by acting on the thermoregulatory center of hypothalamus. It may also be due to rapid growth of tumor, resulting in relative ischemia and hypoxia of tumor tissue, causing tissue necrosis. Or due to the destruction of tumor cells caused by treatment, the above endogenous pyrogen is released, resulting in fever of the body. Tumor fever is generally low to moderate fever, and the body temperature rarely exceeds 38.5℃, which usually does not need special treatment, such as drinking more water or using alcohol bath for physical cooling. The immunity of tumor patients is poor, plus the reduction of white blood cells after chemotherapy, which further reduces the resistance, making tumor patients become a high-risk group for infection. Fever caused by infection can appear above 39℃, and in serious cases, it can cause infectious shock, resulting in patient death. Therefore, once the fever is diagnosed as infection, anti-infection treatment with sensitive antibiotics should be followed to control the infection as soon as possible to avoid serious consequences. In addition, samples of patients’ blood, sputum, urine or stool can be collected for culture to find the causative bacteria, which is very important for choosing effective antibiotics. 3. Brain metastasis: due to the metastasis of malignant tumor to the brain, it affects the function of thermoregulatory center of hypothalamus, resulting in thermoregulatory disorder causing fever, which is clinically known as central fever. The most fundamental treatment for central fever is to remove the metastatic lesions of tumor in the brain. For high fever over 39℃, physical cooling by ice cap or oral antipyretic medicine should be used to reduce fever. 4. Drug fever: It is the drug reaction produced by tumor patients when they undergo drug treatment, which can generally subside by itself.