Phlegm in the throat is actually caused by secretions in the respiratory tract. There are two sources of secretions: 1, from the upper respiratory tract, such as the pharynx, nose, reaching the throat can also form phlegm; 2, from the lower respiratory tract, such as the trachea, lungs have phlegm, phlegm can also stay inside the throat, the cause should be specifically analyzed. If it comes from the upper respiratory tract, in most cases there will be nasal congestion, runny nose, sneezing, mostly caused by phlegm from the upper respiratory tract, and phlegm is caused by rhinitis. If there is fever, prolonged cough, and possibly dyspnea, it is likely to be caused by secretions from the lungs and trachea. So according to the symptoms to be able to specifically analyze how the phlegm in the throat is coming from, if there is simply phlegm in the throat, it is really not good to analyze how it is coming from.