Smoking often has sputum, which may be clinically related to the following reasons: First, when patients smoke for a long time, the tar, nicotine and other toxic substances inside the cigarette are inhaled into the lung trachea in large quantities, leading to inflammatory diseases of the lower respiratory tract. The inflammatory disease leads to an increase in the exudation of mucous membrane, and when the patient coughs, it is coughed into the throat in the form of sputum. In the second case, patients who smoke for a long time tend to damage the mucous membrane of the pharynx, which leads to the formation of phlegm due to the proliferation of lymphatic follicles in the posterior pharyngeal wall and the root of the tongue. In the third case, when patients smoke for a long time, it is easy to induce patients to develop rhinitis and other related diseases, and long-term rhinitis is easy to backflow nasal mucus into the throat, which is also part of the formation of phlegm. In conclusion, chronic pharyngitis can appear as an inflammatory reaction in the upper respiratory tract, lower respiratory tract, and the entire respiratory tract, leading to local exudation, which can form phlegm, so patients try to smoke less to avoid the formation of phlegm.