There are many reasons for the symptoms of dry mouth, and this symptom may be just a disease of the oral cavity, or it may be a local manifestation of a systemic disease in the oral cavity, so a systematic examination of both the oral cavity and the whole body should be conducted. 1, diabetes: diabetes is the most common disease causing dry mouth, early often manifested as dry mouth, thirst, and then develop more drinking, eating, urination and wasting. 2, oral diseases: periodontitis patients with dysbiosis in the oral flora environment, poor oral hygiene will also cause dry mouth. Inflammation of glands such as mumps and submandibular gland inflammation can cause too little saliva secretion, and this can cause dry mouth. Older people with atrophy of salivary glands and degeneration of the function of the glands can also cause dry mouth. In addition, the lack of vitamin B2, oral Candida infection and some oral bad habits and often eat spicy and other stimulating food will cause dry mouth. 3, immune system diseases: the most common immune system diseases that cause dry mouth is dry syndrome, mainly dry mouth, dry eye symptoms, and often salivary gland diseases and rheumatoid arthritis. Once the symptoms of dry mouth appear, you need to go to the hospital for a specific examination to check the cause of the disease, so that the treatment plan can be given accordingly. You can also undergo a Chinese medicine examination and take some Chinese herbs to solve the problem of dry mouth.