The most common reason for getting up and spitting yellow phlegm in the morning is that the number of swallowing in the pharyngeal cavity decreases when you sleep, and the secretions from the pharyngeal cavity are hosted in the pharyngeal cavity for a long time, and bacteria grow and yellow phlegm appears, which is spit out in the morning. If you usually do not have it during the day, you can rinse your mouth more at night before going to bed. If the yellow phlegm is sticky, you can use phlegm-reducing medications, such as Mucosolvan. It is also possible that the secretions in the sinuses back up into the nasopharynx and yellow phlegm appears. Such patients are mostly caused by rhinitis, which can be treated, for example, with nasal rinse medications, such as physiological sea saline rinse of the nasal cavity. If the inflammation of the secretions in the nasal cavity is reduced, the spitting up of yellow sputum in the morning will be reduced.