The symptoms of phlegm and runny nose are caused by the following factors: 1. Inflammatory infection of the upper respiratory tract: the occurrence of acute and chronic inflammation of the throat may be caused by long-term excessive use of voice, smoking, drinking, eating spicy and stimulating food, etc., and often suffer from respiratory bacterial and viral infections, which can easily cause pain, discomfort and phlegm symptoms in the throat. 2, Rhinitis factor: patients often because of acute and chronic rhinitis, acute and chronic sinusitis, allergic rhinitis and other disease factors, causing runny nose symptoms, may appear clear nasal discharge, mucopurulent nasal discharge symptoms, some patients may also appear nasal discharge backward into the throat, easily triggering increased phlegm in the throat.