There are many reasons for excessive salivation, which can be categorized into genuine and pseudo-salivation in general. The main causes of true salivary hypersecretion are: stomatitis, pharyngitis, lingual inflammation, gingivitis and other oral diseases, as well as dentures inappropriate stimulation; mercury, lead, iodine, arsenic, and nicotine and other drugs or stimulation; encephalitis, cerebral palsy, epilepsy, Parkinson’s syndrome, vegetative nerve disorders and other neuropsychiatric disorders; sudden goiter, diabetes mellitus, and other diseases of the endocrine system. Pseudohyposalivation is the result of obstruction of the oral salivary route. The main reasons are, esophageal stenosis or tumor, scarring and other pathway obstacles; oral cavity, pharynx and other parts of the surgery caused by swallowing nerve paralysis, resulting in oral saliva is difficult to swallow; and nerve, lingual nerve and jaw motor dysfunction; the elderly salivary glands atrophy, can be due to taking drugs leading to drug-induced salivary secretion and so on. You should carry out specialized examination to clarify the specific causes and do symptomatic treatment.