Dry mouth and tongue with white thick tongue coating may be caused by dampness and heat or spleen deficiency and dampness obstruction. 1. Dry mouth and tongue suggests that there is a deficiency of yin fluid. The deficiency may be absolute, that is, the body is less yin fluid, this is mostly heat evil injury to the yin. It may also be a relative shortage, that is, the yin fluid stop gathering, can not bear, mouth and tongue loss of moisturizing, resulting in dry mouth and tongue. 2. If the tongue coating is white and thick and the tongue color is reddish-reddish, it may be dampness to curb the heat. Dampness is internal obstruction, so the tongue coating is white and thick; dampness is internal obstruction, the evil heat can not be dispersed, and the yin is injured when it is long, so the yin liquid in the body is reduced, so the mouth is dry and the tongue is red and dark. 3. If the tongue coating is white and thick and the color of the tongue is normal, then it may be the spleen deficiency and dampness. The spleen is the master of transportation, if the spleen is weak and does not transport the water and dampness, so there will be a white thick tongue coating. The spleen is able to transmit and distribute the yin fluid, if the spleen is weak, the yin fluid can not be carried in the mouth, the yin fluid is insufficient, the mouth and tongue are not moisturized, so there will be a dry mouth and tongue. If the above discomfort occurs, it is recommended to go to the hospital in a timely manner to clarify the cause of the disease, and should not be taken lightly, so as not to delay the condition.