Old phlegm inside the throat may be chronic rhinitis, sinusitis, chronic pharyngolaryngitis, reflux pharyngolaryngitis, etc., and should be promptly consulted to identify the cause of the disease. 1. Chronic rhinitis, sinusitis: patients may suffer from chronic rhinitis, sinusitis and other conditions, the secretion will backflow postnasal drip, flow to the throat will cause the symptoms of phlegm in the throat. 2. Chronic pharyngitis: For example, patients with simple pharyngitis or hypertrophic pharyngitis will often have phlegm in the throat, pharyngeal foreign body sensation and other symptoms. 3. Reflux laryngitis: patients with reflux laryngitis will also experience frequent phlegm in the throat, constant throat clearing, mute voice, acid reflux, heartburn and other symptoms. If the throat often appears to have phlegm, you should go to the hospital, after a clear diagnosis, to carry out targeted treatment.