The recurring fever of the flu may be due to the pathogenic microorganisms that attack the human body being too tenacious, or it may be due to the frequent exposure to these pathogenic microorganisms in order to make just the right body again attacked by external evil and fever. When external evil attacks the body’s muscle couples, the body’s positive qi will fight against it, and the positive qi is yang-heat. When the patient’s own positive energy is sufficient to resist the external evil, that is, the body temperature will also slowly return to normal. If the pathogenic microorganisms are too tenacious and one’s own positive energy cannot be completely dispersed, it may also cause the patient to have recurrent fever. If the patient’s environment is full of bacteria, viruses and other pathogenic microorganisms, even if the patient’s own vital energy is sufficient to disperse the external evil, the patient will still be attacked by new external evil and will continue to have fever. Therefore, isolation from the unclean environment is especially important for the treatment of cold and fever. In addition, if the patient does not pay attention to warmth and is attacked by wind, cold and dampness, the condition will recur and the fever will recur. The main reason for the recurrence of fever is the presence of many pathogenic microorganisms in the environment. The symptoms may also occur when the patient’s own positive energy is not sufficient.