Cold, cough and sputum are commonly caused by cold, rain and late night. These precipitating factors make the immune system lowered and vulnerable to the invasion of some pathogens, such as viruses, bacteria and mycoplasma, which make the mucous membrane of the upper respiratory tract appear inflammatory reaction with congestion, edema and exudation of inflammatory secretions. Generally, the condition and etiology can be clarified through blood tests and CT of both lungs, and even sputum can be taken to find or culture the pathogens.