There are many causes of dry mouth and lips, both physiological and pathological, as follows: a. Physiological dry mouth and lips are most commonly caused by drinking too little water, and dry mouth and lips caused by excessive organism expenditure in a hot environment. Second, it can be seen in lip inflammation, lip inflammation is due to non-stop licking, so that the epithelial cells on the surface of the mouth and lips are shed, and thirst often occurs. Third, it can be seen in diabetic patients, who, in addition to thirst, drink more, urinate more, eat more, and lose weight, which can be found when testing blood sugar. IV. It can be seen in hyperthyroidism. Due to the excessive expenditure of the organism in hypermetabolic syndrome, the patient can also be thirsty. Fifth, it can be seen as a result of abnormal secretion of hypothalamic-pituitary antidiuretic hormone. Sixth, dry mouth and lips can also be caused by dryness syndrome. In conclusion, when dry mouth and lips occur, first of all, except for physiological reasons, then go to the hospital to check the pathological reasons, and according to the etiology of specific treatment.