White tongue moss may be normal tongue moss; it may also be caused by the beginning of superficial symptoms, external cold and dampness. Normal white moss is produced by the stomach qi, thin and flat in the middle and root of the tongue, with even granularity, moderate dryness and moistness, and the color of the tongue is like normal. If the moss is thin, white and moist, it may be normal, or it may be the beginning of superficial symptoms, or it may be the lightness of internal symptoms. If the moss is thin and white and slippery, it is mostly due to external cold and dampness, or spleen and kidney yang deficiency (deficiency of yang qi in the spleen and kidneys), and water-dampness stagnation (water-dampness stays in the body). If the moss is thin white and dry, it is mostly caused by external wind-heat. If the coating is white and greasy, it is mostly due to internal stagnation of dampness and turbidity, or phlegm-drinking (pathological products formed by impaired metabolism of water and fluid), or accumulation of food (indigestion of food and its accumulation in the stomach). If the tongue is white and accompanied by other uncomfortable symptoms, it is recommended to seek prompt medical treatment.