The cause of dryness and thirst should be identified and treated according to the cause. Dryness and thirst caused by diabetes should be treated as soon as possible by oral hypoglycaemic drugs and insulin injections according to the doctor’s instructions; dryness and thirst caused by hyperthyroidism is treated with anti-thyroid drugs and radioactive iodine; dryness and thirst caused by chronic renal failure is best treated with renal replacement therapy.