The more water you drink, the drier your mouth may be due to a physiological phenomenon caused by hot weather, etc., but also due to diabetes, immune deficiency and other causes of disease, you should seek medical attention to clarify the cause of the disease. 1. Physiological phenomenon: when the weather is hot, the temperature is usually higher, the body fluid metabolism is faster, easy to cause dry mouth and other phenomena, resulting in drinking water is difficult to relieve. 2. Pathologic: (1) diabetes: diabetic patients usually have high blood sugar, high blood sugar is easy to cause osmotic diuresis, resulting in the loss of body fluids too fast, thus causing long-term dry mouth, thirst and other symptoms occurring frequently resulting in drinking water can not be relieved. (2) Dry Syndrome: It is a disease that occurs due to immune system disorders, and after the onset of the disease, it can involve the salivary glands, sweat glands, etc., leading to a decrease in glandular secretion. Involvement of salivary glands will cause dry lips and mouth, thirst, and it is difficult to relieve the symptoms after drinking water. The more water you drink, the more dry your mouth is due to a variety of reasons, it is recommended that patients seek medical attention in a timely manner to clarify the specific causes of the disease and then follow the doctor’s instructions to avoid delays in the condition.