Clinicians need to consider many aspects for the diagnosis of patients with recurrent fever, which can be broadly divided into infectious and non-infectious. The following are common clinical causes of recurrent fever, as follows: (1) Common bacterial and viral infections: the most common are caused by Streptococcus pneumoniae, Staphylococcus aureus, Klebsiella pneumoniae, and influenza viruses Respiratory system infections pneumonia, lung abscess and influenza virus infection can lead to recurrent fever; gastrointestinal digestive system infections such as acute gastroenteritis, hepatitis, liver abscess, cholecystitis, pancreatitis; urinary tract infections, all of the above can lead to recurrent fever. Clinically, for recurrent fever, doctors will conduct blood culture and drug sensitivity test to find the pathogenic bacteria for symptomatic medication, and the fever will be relieved more quickly. (2) Tuberculosis infection is typically characterized by recurrent fever, mostly manifesting as low fever and night sweats in the afternoon. (3) Special infections: clinically common infections with fungi, mycobacteria and multi-drug-resistant bacteria are prone to recurrent fever, such as pulmonary Aspergillus infection and various drug-resistant bacterial infections often have recurrent fever and a long course, treatment is more difficult, less drugs can be applied and the cost is higher. In addition, typhoid fever, paratyphoid fever and viral encephalitis can lead to recurrent fever. 2, non-infectious diseases (1) rheumatic immune diseases: rheumatism, rheumatoid and systemic lupus erythematosus, systemic vasculitis and other diseases can lead to recurrent fever. (2) Neoplastic diseases: certain hematological tumors, lymphomas, tumors of the lung and other sites can lead to recurrent fever. (3) Other special conditions: adverse reactions to certain drugs, allergic reactions, and abnormalities in the thermoregulatory center due to brain injury can also lead to recurrent fever. The diagnosis of fever is very complicated and sometimes clinicians may have a headache, as there are hundreds of diseases that can cause recurrent fever. If you have recurrent fever, it is recommended that you seek medical attention promptly to find the cause of the disease and treat it symptomatically.