There is no such thing as a black tongue as an omen of any disease. From the point of view of Chinese medicine, black tongue coating may be caused by dyeing the moss, or it may be caused by diseases such as cold evils within the body (cold evils stopping in the body), phlegm and dampness within the body (phlegm and dampness of evils stopping in the body), and so on. If you consume too much dark-colored food, such as cola, mulberry, chocolate, etc., the pigment in the food is likely to lead to local melanin precipitation, which leads to black tongue coating, and this condition does not usually require treatment. The tongue coating due to the cold syndrome is grayish-black, moist and reddish, often accompanied by a fear of cold, white face without luster, cold hands and feet, long and clear urine and loose stools. Commonly used proprietary Chinese medicines include Liangshi Pill and Pianzi Lizhong Pill. It should not be used by patients with cold and fever. Due to internal stagnation of phlegm-dampness, the tongue coating is grayish-black and moist, and the tongue color is pale white, often accompanied by head distension and heaviness, chest tightness, self-consciousness of heaviness of the body, joint pains, clear and long urine, and unsmooth stools. Commonly used proprietary Chinese medicines include Wu Ling San and Ten Jujube Pills. Among them, those who are physically weak and pregnant women should not take Ten Jujubes Pill. If you have any related symptoms, it is recommended that you consult a doctor in time, and do not use medication on your own to avoid any related adverse reactions.