Sudden dry mouth may be related to uremia, hypokalemia, dry syndrome and other factors. 1. Uremia: If there is a serious lack or partial lack of Argipressin in the body, it will lead to impaired reabsorption of water in the renal tubules, thus causing symptoms such as dry mouth, polyuria and polydipsia. Usually, you can choose desmopressin under the guidance of the doctor for treatment, which can effectively relieve the symptoms of dry mouth and other discomforts. 2. Dry syndrome: it is usually due to the abnormal proliferation of B-lymphocytes and infiltration of tissue lymphocytes, which leads to the abnormality of exocrine glands such as lacrimal and salivary glands, and the reduction of salivary secretion, which leads to the symptoms of dry mouth and other discomforts. Usually, methotrexate, azathioprine, immunoglobulin and other drugs are needed for treatment. 3. Hypokalemia: If prolonged fasting and vomiting may lead to the loss of potassium ions in the body, which may cause necrosis of renal tubular epithelial cells and decrease of urinary concentrating function, so dry mouth and increased nocturia may occur. It is recommended to take potassium chloride orally for treatment under doctor’s guidance, and electrolytes need to be rechecked after potassium supplementation treatment. When the above symptoms occur, it is recommended to consult a doctor in time, and under the doctor’s guidance to identify the cause of the disease and then carry out treatment or use of medication.