Dryness of the mouth can occur except for the first day of eating salty food, working outdoors, hot and dehydrated, or after heavy physical work or heavy physical work, or heavy exercise training. Pathologically, it is common in diabetes mellitus, with some accompanying symptoms such as excessive drinking, polyuria, polyphagia, weight loss, and elevated blood sugar when checking blood sugar. Hyperthyroidism can also produce a dry mouth sensation, which is due to hypermetabolic syndrome and dehydration of the body. Dryness syndrome is most common in middle-aged and elderly people. It is caused by the impaired secretion of salivary glands, and in addition to the dryness of the mouth, the flow of tears is also reduced. There are also patients with uremia, where polyuria and thirst are evident due to abnormal secretion of antidiuretic hormone by the pituitary gland. The occurrence of thirst and dry mouth requires further examination of what causes it, and then symptomatic treatment is given.