Excessive sputum in the mouth may be caused by chronic rhinitis, reflux esophagitis, bronchitis and other reasons. 1. Chronic rhinitis: Chronic rhinitis will cause inflammation of the nasal mucosa, and the increased secretion can flow into the throat, causing the patient to have a lot of sputum in the mouth. 2. Reflux esophagitis: Gastric acid refluxes from the cardia in patients with reflux esophagitis, and acidic water and acidic gas can stimulate the mucous membrane of the pharynx, causing increased secretion. This will cause the patient to have a lot of sputum in the mouth. 3. Bronchitis: The respiratory tract of patients with bronchitis will secrete a large amount of inflammatory exudate due to the stimulation of infection, forming a large amount of phlegm. There are many other causes of phlegm in the mouth, it is recommended that the patient should consult the doctor in time, improve the relevant laboratory tests to clarify the cause of the disease, and then follow the doctor’s instructions for treatment.