If cancer patients always have fever, it is necessary to figure out what exactly causes the fever, because there are several possibilities to cause fever in cancer patients, and then it can be treated symptomatically as follows: 1. Tumor fever: Tumor fever refers to the exclusion of infectious factors, the application of antibacterial treatment is ineffective, due to tumor cell necrosis or tumor cell secretion of biological factors, which causes fever in patients. The characteristics of this condition are mainly low fever, fixed fever every afternoon or evening, and the temperature usually does not exceed 38.5℃, and it occurs repeatedly and continuously. The most effective treatment in this case is to treat the primary disease. Only when the cancer is well controlled and the cancer regresses, the fever can be effectively relieved. Besides, non-steroidal anti-inflammatory and antipyretic drugs can be applied, which can also relieve, but it is not recommended for long-term use, because these drugs have side effects. 2. Infectious fever: If the cancer patient has infectious fever caused by poor constitution and weak immunity, drugs should be used for the pathogens that may be infected, such as severe drug-resistant Klebsiella infection, which may require very high-level antibiotics. All of these are based on the detection of the pathogen and the drug sensitivity test to select the medication to control the infection and then allow the fever to resolve.