The symptoms of frequent thirst can have many causes, the most important of which may be oral diseases or local manifestations of systemic diseases in the oral cavity. Therefore, a systematic examination of both the oral cavity and the whole body should be performed. Among oral diseases, periodontitis is the most likely cause of frequent symptoms of thirst, because patients with periodontitis have a dysbiosis of the oral flora environment and poor oral hygiene, so that a large number of harmful bacteria are produced, and these harmful bacteria stimulate the oral mucosa, which can cause the occurrence of gum bleeding and other diseases, all of which can cause people to be thirsty frequently. In addition, inflammation of glands such as mumps and submandibular glanditis can cause too little saliva secretion, which can cause frequent thirst. In the elderly, the salivary glands are atrophied and the function of the glands is degraded, which can also cause frequent thirst. In addition, lack of vitamin B2, oral candida infection and some bad habits of the oral cavity as well as eating spicy and other stimulating foods can cause frequent thirst. In addition to major oral diseases, systemic diseases such as diabetes, immune system diseases, etc. can also cause frequent thirst. Therefore, once the symptoms of frequent thirst appear, you need to go to the hospital for a specific examination to check the cause of the disease so that a treatment plan can be given accordingly.