The causes of colds for no reason are considered to be related to factors such as low immunity, poor lifestyle and dietary habits, and chronic respiratory diseases. 1. Low immunity: patients will suffer from low immunity, which will reduce the defense function of the whole body or the local defense function of the respiratory tract. Therefore, it will increase the probability of catching a cold for no reason. 2. Bad living and eating habits: crowded environment, sedentary lifestyle, poor nutrition, smoking, drinking, rain and other bad living and eating habits will also increase the probability of colds. 3. Chronic respiratory diseases: If the patient himself has chronic respiratory diseases, such as pharyngitis, laryngitis, etc., it may cause colds when the pathogen is infected by neighboring organs. Patients with symptoms of colds for no apparent reason should cooperate with their doctors to identify the specific cause as soon as possible and give appropriate examination and treatment.