If a patient presents with dry mouth but not thirst, the cause needs to be discussed from both Chinese medicine and Western medicine. First, from the perspective of Chinese medicine, the most common cause is physical deficiency, often due to kidney yin deficiency and lung deficiency, which leads to dry mouth, but not necessarily to irritable thirst. Secondly, from the perspective of Western medicine, the most common factor for dry mouth but not thirst is endocrine and metabolism, the most common diseases such as hyperthyroidism, in the case of hyperthyroidism patients will have dry mouth, but if there is no obvious kidney hypofunction, there is no obvious diuretic effect, at this time only the clinical symptoms of dry mouth will appear. Thirdly, dry mouth can also occur in diabetes mellitus, and at this time there is also a thick white tongue coating and less fluid, but if there is no certain kidney damage, no diabetes mellitus combined with nephropathy, and there is no obvious diuretic effect at this time, there will be dry mouth but not thirst.