The main contents of tongue diagnosis include observation of tongue quality and tongue coating. Looking at the quality of the tongue includes the tongue spirit, tongue color, tongue shape, tongue posture and sublingual veins; looking at the tongue moss includes the moss quality and moss color.
Tongue color is divided into light red, light white, red, reddish-red, greenish-purple. Pale red tongue can refer to a healthy person or a person with a mild condition; pale white tongue is mainly for people with deficiency of Qi and Blood, and Yang deficiency. The tongue color of a patient with heat syndrome can be red; reddish-red tongue is full of internal heat or yin deficiency and fire (deficiency of yin and essence in the body, resulting in hyperactive deficiency and fire); and greenish-purple tongue can be cold, hot and stagnant. Tongue shape has old and young tongue, fat and thin tongue, tooth mark tongue, swollen tongue, puncture tongue, cracked tongue. Tongue shape includes soft tongue, strong tongue, crooked tongue, fluttering tongue, spitting tongue and shortened tongue. Observe the length, thickness, curvature and color of the veins under the tongue. Moss quality is mainly to observe the change of thickness, dryness, greasiness and rotting of the tongue moss, such as the bias of the whole. There are white moss, yellow moss, gray and black moss. White moss main cold evidence, surface evidence, wet evidence, but also can be a healthy person. Yellow moss is mostly internal evidence, heat evidence. Gray and black moss is the main internal evidence, may be the extreme heat or cold.