Thirst, dry mouth is a signal of the lack of fluid in the human body, reminding people should be timely hydration, the common causes of dry mouth are mainly the following: 1, dry syndrome, patients with reduced saliva, swallowing dry food is very difficult, the tongue and corners of the mouth cracked, most patients with swollen parotid glands. 2, diabetic patients often have symptoms of thirst and dry mouth, diabetic tasks due to polyuria, water loss in the body, dry mouth. In general, thirst and dry mouth as an early sign of diabetes. 3, hyperthyroidism, hyperthyroidism patients with clinical symptoms of dry mouth, excessive sweating, protruding eyes, increased metabolism, etc. 4, salivary gland abnormalities, with abnormal salivary gland development, chronic parotitis, low parotid function in the elderly, etc. 5, salty diet or drinking too little water. 6, drug dry mouth, valium, diuretic acid, antidepressants, digitalis, anticholinergic Drugs can cause thirst and dry mouth.