Phlegm in the mouth is mainly considered to be caused by inflammation of the throat or due to inflammation of the trachea and lungs coughing up phlegm, which is often sticky and not easy to cough up or spit out. Most of the cases are caused by viruses, bacteria and other pathogenic microorganisms. Generally, it is necessary to dilute the sputum with aminoglutethimide to promote the discharge of sputum, as well as to use drugs such as snake bile and Sichuan shellfish liquid and acute syrup to relieve cough and resolve sputum. If the symptoms are more serious, antibacterial and antiviral drugs should be used for active treatment, and nebulized inhalation can also be used to promote the discharge of phlegm. Drinking more water, eating more fresh vegetables and fruits, and exercising properly are all beneficial to the rapid elimination of phlegm. If the symptoms are serious, routine blood tests, sputum tests and drug sensitivity tests should be done to select sensitive antibacterial drugs for treatment according to the test results.