Black tongue can appear in two cases: extreme cold, extreme heat, dyeing moss can also lead to, as follows: 1, if it is extremely cold, moss is on the basis of greasy, looking like a layer of oily mud like black, generally is partial cold, lack of yang qi, excessive accumulation of moisture caused by black moss; 2, if it is extremely hot, it is dark and dry moss, the tongue thicker, but very dry in the case of the appearance of black moss, black moss accompanied by the bottom of the yellow-brown moss appeared, the black moss accompanied by the appearance of yellow-brown moss. The surface is black, is from the heat dry heat to the depth of the performance of the polar heat evidence. In short, the black tongue moss needs to be actively dealt with, as long as the distinction is not the case of dyeing the moss, it is necessary to deal with the extreme heat or cold with medication, and the general food adjustment is no longer in place. When using medicine, pay attention to other signs of the body, in addition to the differentiation of the quality of the moss, pay attention to the patient’s own physical sensations, pulse sensations, and physical condition, to differentiate between heat and cold.