Intermittent low-grade fever is most likely to be caused by the occurrence of lymphoma, infectious diseases (e.g., tuberculosis, etc.), or rheumatologic-immune diseases (e.g., connective tissue disease, etc.). When lymphoma occurs, the tumor cell load in the patient’s body increases significantly as the disease progresses, and intermittent low-grade fever, unexplained lethargy, night sweats, and other manifestations may occur, which are clinically referred to as B-symptoms of lymphoma. In patients with fever caused by lymphoma, the body temperature is mostly around 38 degrees Celsius, without chills, chills, cough and sputum and other clinical manifestations of bacterial infection. These patients may have progressive painless enlargement of multiple lymph nodes throughout the body, and lymph node biopsy pathology is required to make a definitive diagnosis. Tuberculosis is a disease caused by Mycobacterium tuberculosis infection, such as tuberculosis. Typical cases may present with low afternoon fever, night sweats, and unexplained weight loss. There is variability in clinical manifestations from patient to patient. In patients with malignant solid tumors (e.g. gastric cancer), when the tumor cells or necrotic tissues in the body are absorbed, absorption fever may occur, which is non-inflammatory fever and may be manifested as intermittent low-grade fever. In autoimmune diseases including rheumatoid arthritis, systemic lupus erythematosus, connective tissue disease, etc., the body may undergo aseptic inflammation, which may also manifest as intermittent low-grade fever. It is recommended that patients with intermittent low-grade fever consult a doctor in time, and actively identify the cause of the disease and treat the cause of the disease.