Generally, diarrhea accompanied by fever is associated with gastrointestinal infections. Other causes, such as tumors and tuberculosis, may also cause fever. When eating food or drinking water infected by bacteria or viruses, pathogenic microorganisms will be parasitized in the human intestine, which will irritate the mucous membrane of the intestinal wall and also release some harmful substances in order to damage the function of human organs. Due to the effect of pyrogenic sources, the thermoregulation point is moved upward, which causes the imbalance of the function of the thermoregulation center, and the symptoms of fever appear. In addition, the infestation of bacteria, viruses, parasites, etc. will also stimulate the immune system of the human body, and through a series of immune reactions and nerve reflexes, the human body will experience nausea, vomiting, loss of appetite, headache and other uncomfortable symptoms. In patients with cancer tumors, due to the growth of cancer cells as well as necrosis, liquefaction, and ulceration, absorption fever may occur due to absorption by the body, and infectious fever may also occur due to infection of surrounding tissues. In addition, cancerous tissues can also develop symptoms such as fever due to stimulating the body’s immune response. Tuberculosis, such as pulmonary tuberculosis, etc. This type of disease is identified as a yin deficiency disease in Chinese medicine, and will present with symptoms such as prolonged low-grade fever, afternoon hot flashes, heat in the hands and feet, and diarrhea. Diarrhea and fever should first be considered acute gastroenteritis, but serious diseases such as tumors should not be ignored and still require vigilance.