There is no “old man dry mouth prescription”. Dry mouth need to exclude drinking too little water and other reasons, Chinese medicine believes that pathologic dry mouth has a variety of causes, such as heat injury, Yin deficiency and fire (Yin essence loss in the body, the emergence of deficiency and fire), dampness and heat, etc., according to the cause of the selection of White Tiger soup, Zhi Bai Di Huang Pills and other prescriptions for the treatment. Dry mouth first needs to exclude the causes such as drinking too little water, such as drinking less water, can also cause dry mouth, should be timely replenishment of water. If it is pathologic, Chinese medicine believes that dry mouth is related to heat injury to fluid, yin deficiency and fire (deficiency of yin and essence in the body, resulting in hyperactive fire), dampness and heat, phlegm (pathological products formed by impaired metabolism of fluid), and stasis of blood, etc. According to the specific causes, we can choose the relevant prescriptions for the treatment. 1. Injury to fluids by heat: if the stomach is hot and blazing, manifesting as a great thirst for cold drinks, high fever and sweating, it can be treated with Baihu Tang and other medicines. 2. Yin deficiency and fire exuberance (deficiency of Yin essence in the body, hyperactive fire): manifested as dry thirst and throat, aggravated at night, night sweating (abnormal sweating after going to sleep, and sweating stops after waking up), and heartburn and heat (heat in the hearts of the hands and feet, and self-consciousness of irritability and stuffiness of the heart and chest), which can be treated with Zhi Bai Di Huang Wan and other formulas. 3. Phlegm-beverage (pathological products formed by impaired metabolism of water and fluid): manifesting as dry mouth, liking hot drinks but not much, or vomiting when water is taken in, can be treated with medicines such as Wu Ling San. The above drugs should be taken under the guidance of a physician. Causes of dry mouth in the elderly more causes, such as dry mouth, should go to the hospital in a timely manner for examination, to clarify the cause of the disease, as soon as possible for targeted treatment.