Tongue Diagnosis: An Overview of Tongue Color in Disease Diagnosis
The color of the tongue refers to the hue of the tongue body. It can generally be categorized into several types: pale white, light red, red, crimson, and blue-purple. Essentially, these can be divided into two main categories: light red, red, and crimson, which represent varying degrees of red from light to dark; while purple, light purple, and blue-purple indicate a gradual decrease in red components and an increase in blue components.
The normal tongue color is often light red, but many people are unsure which shade of light red is considered normal. Each individual is different; for instance, the light red of a child differs from that of an adult. During tongue diagnosis, it is said that one type of light red is normal while another is also considered normal. However, when comparing the so-called normal light red tongues of two different individuals, one may find significant differences in pigmentation. Here, we provide a small knowledge point for reference: generally, when examining the tongue, the determination of whether the tongue color is normal is made by comparing the color of the tongue body with that of the oral mucosa. If the two colors are similar, it is usually considered a normal light red tongue. If the tongue body is darker than the oral mucosa, it is classified as a red tongue; conversely, if the tongue body is lighter, it is classified as a pale tongue.
When the body is ill, the color of the tongue body typically changes accordingly. Therefore, in Traditional Chinese Medicine (TCM), aside from light red being a normal tongue color, sometimes a light red tongue can also indicate illness. All other colors are considered pathological.
General Rules for Tongue Color Diagnosis:
Color: From light to dark
Light Dark
Pale white tongue → Light red tongue → Red tongue → Crimson tongue → Blue-purple tongue
Deficiency syndrome, cold syndrome Normal (Red crimson) heat syndrome Stagnation due to cold, heat, or qi stagnation
Generally speaking, a tongue color that trends towards light indicates a deficiency syndrome or cold syndrome. Deficiency syndrome is often due to blood deficiency, where insufficient blood leads to a lighter tongue color; alternatively, cold can also cause a pale appearance, which is a major reason for a lighter tongue. Using symbolic thinking, this can be understood as insufficient fire; if there is not enough fire, there is not enough heat, leading to excess cold. Thus, in cold winter, snow falls, and the icy landscape is typically white; a pale tongue is better understood in relation to cold. On the other hand, blood deficiency can also lead to a pale appearance, so in TCM, white typically indicates either blood deficiency or cold.
If the tongue color trends towards red or crimson, it usually indicates an increase in internal (fire) heat evil or a deficiency of yin, where insufficient yin fails to restrain yang, resulting in redness. However, redness caused by heat evil is bright, while redness due to yin deficiency is generally dull; overall, a red or crimson tongue indicates that yang is relatively more abundant than yin.
Conversely, if the tongue trends towards blue, purple, or bluish, it indicates a reduction in the “red elements”. In TCM, red represents yang; a decrease in red elements can also signify a reduction in yang, meaning that a blue-purple tongue is generally considered to indicate extreme cold or extreme stagnation, although it can also indicate heat, but in a more specific context.
Therefore, when using symbolic thinking to analyze the tongue, tongue diagnosis becomes much simpler; the key is whether one can effectively utilize this way of thinking.