Long-term phlegm in the throat should be alert to the occurrence of sinusitis, tonsillitis, pharyngitis. 1. Sinusitis: If sinusitis occurs, there will be secretions deep in the bottom of the nose, which are not easy to flow out of the nasal cavity, and can flow backward through the nasopharynx to the pharynx, resulting in the long-term presence of phlegm in the pharynx. The secretion may belong to the nasal mucus, not the phlegm secreted by the pharyngeal cavity. 2. Tonsillitis: occurs mostly due to bacterial infections, accompanied by redness, swelling and pain in the tonsils, which can lead to increased secretions and the presence of phlegm in the throat. 3. Pharyngitis: can be triggered by bacterial infection or viral invasion or stimulation by adverse physical and chemical factors, which will result in itching and pain in the throat and phlegm in the throat for a long time. If there is phlegm in the throat for a long time, it is recommended to consult a doctor for a clear diagnosis.