The causes of dry mouth include physiological factors (drinking less water) and pathological factors (diabetes, dry syndrome, etc.), which need to be specifically analyzed. 1. Physiological factors: when drinking less water, the body’s fluid intake is less than the amount of discharge, which will produce the symptoms of dry mouth and astringency, and drinking more water to increase fluid intake can generally improve. Normal people need to drink about 1500 to 2000ml of water per day, if there are strenuous activities, sweating, etc., you need to increase the amount of fluid intake. 2. Pathological factors (1) Diabetes mellitus: when blood sugar rises, the concentration of solutes in the glomerular fluid increases, resulting in osmotic diuresis, and increased urine output leads to excessive fluid loss, resulting in dry mouth and astringent symptoms, accompanied by polyuria, weight loss and other symptoms, and glucose tolerance test and other tests can assist in making a definitive diagnosis. (2) Dry syndrome: This disease is an immune system disease that involves exocrine glands. Due to the damage of secretory glands, symptoms such as dry mouth, dry eyes, and reduced tear secretion may occur, and tests such as salivary flow rate and autoantibodies may assist in making a clear diagnosis. Dry mouth and astringency may also be caused by other reasons. If the symptoms are not relieved after adequate hydration or if they persistently worsen, it is recommended to consult a doctor in time to avoid delaying the condition.