Dry mouth is a symptom caused by a lack of saliva in the mouth. If the amount of saliva produced is relatively low and does not completely reach the amount of saliva consumed, the phenomenon of dry mouth and astringency will occur. If you have diabetes or hypertension, you will often experience thirst and dry mouth. Elderly people also have age-related changes, and generally older people may experience atrophy of salivary gland glands, and the amount of saliva may be secreted too little. In addition, those who have major tumor diseases or a history of radiotherapy may have dry mouth symptoms. There are also some side effects caused by drugs, so you should not use drugs indiscriminately, some long-term oral antibiotics, when there is a disease will be taken in large quantities will easily cause the disorder of intraoral flora, so also prone to dry mouth symptoms, so it is recommended to seek medical advice in a timely manner when there is disease.