Inheriting the fire of Qi Huang, a public account with substance and warmth
The tongue is closely linked to diseases, and through the different appearances of the tongue, we can judge the internal disease conditions. This is a unique diagnostic method in Traditional Chinese Medicine (TCM). The emphasis on tongue observation in TCM stems from the relationship between the tongue and the internal organs.
▢Written by/Tang Yun
We previously mentioned that “the heart opens to the tongue,” meaning that the tongue is the organ through which the heart exchanges information with the outside world. Changes in heart function can be reflected through the tongue, which is why TCM refers to the tongue as “the external representative of the heart.” The term “representative” refers to signs and indications. The heart is the “ruler of the organs” in the human body, governing various life activities. Therefore, as the “external representative” of the heart, the tongue can naturally reflect the overall state of life activities in the body. Thus, when the internal dynamic balance of the body is disrupted, leading to various disease symptoms, the tongue will also exhibit corresponding changes. By observing and analyzing these changes, we can obtain strong evidence of disease, which is why TCM places great importance on tongue observation.To understand the relationship between the tongue and diseases, it is necessary to first understand the composition and structure of the tongue.
The tongue is attached to the floor of the mouth, the mandible, and the hyoid bone, with two surfaces: the upper surface is called the tongue dorsum, and the lower surface is called the tongue ventrum. On the tongue dorsum, there is a thin and transparent mucous membrane, which has many small projections called lingual papillae. Based on the shape of the lingual papillae, we classify them into three types: filiform papillae, fungiform papillae, and circumvallate papillae. The first two types are distributed in the anterior part of the tongue, while the latter is located near the root of the tongue. The fungiform and circumvallate papillae contain taste buds, which are the primary sites for taste sensation in the human body. TCM classifies the tongue into two main parts based on its visual characteristics: the tongue body and the tongue coating. The tongue body, also known as the tongue substance, consists of muscle and vascular tissue, containing three directions of transverse striated muscle and abundant blood. Under normal conditions, it appears light red and can move flexibly. The tongue coating is the layer of coating on the tongue body, primarily composed of filiform papillae. Under normal conditions, it appears white, evenly distributed across the surface of the tongue, closely adhering to the tongue surface, and cannot be scraped off. Through this coating, the light red tongue body can be faintly seen, so TCM describes a normal tongue appearance as “light red tongue with thin white coating.” In a diseased state, both the tongue body and tongue coating will undergo various changes. By observing the tongue body and tongue coating, we can determine the location and nature of the disease, providing a basis for diagnosis.
First, let’s look at the relationship between the tongue body and diseases. Similar to previous observations, the examination of the tongue body focuses on four aspects: spirit, color, shape, and state.
Spirit of the tongue, refers to the overall appearance of the tongue, which is our first impression when we see the tongue. Generally, the spirit of the tongue includes two aspects. One is vitality, where “vitality” refers to a tongue that is red, moist, and vibrant, indicating a healthy state, suggesting that the organ systems are full of vital energy and functioning normally, which indicates a mild disease that is easy to recover from; “lack of vitality” refers to a tongue that is dry, dull, and lifeless, indicating a depleted state of the organ systems, suggesting a severe disease that is difficult to recover from.The second aspect is mobility. If the tongue body moves freely and flexibly, it indicates vitality, representing a mild disease; if the tongue body is stiff, inflexible, or exhibits slurred speech or weakness, it indicates a lack of vitality, representing a severe disease. Through the spirit of the tongue, we can make a preliminary judgment about the nature of the disease and the condition of the organs. To gain a more detailed understanding of the disease, we need to carefully observe the color, shape, and state of the tongue body.
The color of the tongue body is mainly related to the rich blood supply in the tongue body. Under normal conditions, it appears light red. Changes in the color of the tongue body are closely related to the arterial blood supply to the tongue. Insufficient blood supply can lead to a lighter color, while excessive blood supply can darken the color. Blood stasis can also darken the color and give it a dark hue. Let’s look at several common types of changes in tongue body color and understand their clinical significance.
Light white tongue. The tongue body color is lighter than the normal light red, even lacking blood color, referred to as a light white tongue. A light white tongue is caused by insufficient arterial blood supply to the tongue, such as due to blood deficiency or low blood pressure. We have discussed that the generation of qi and blood in the body mainly relies on the spleen’s transportation function, and the normal circulation of blood in the vessels requires the driving force of yang qi. Therefore, the appearance of a light white tongue is commonly seen in two situations: one is spleen deficiency leading to insufficient qi and blood, or prolonged illness, severe illness, or excessive bleeding leading to excessive consumption of qi and blood; the second is weak yang qi, which is unable to promote blood circulation.
Red tongue. A red tongue is darker than a light red tongue, even appearing bright red. A red tongue is caused by excessive arterial congestion in the tongue, which is often due to an accelerated blood circulation speed. Therefore, red tongues are commonly seen in various febrile diseases, such as internal heat or external heat invasion. If we also consider the tongue coating on the surface of the tongue, we can distinguish whether this heat condition is due to deficiency or excess. A red tongue with a yellow thick coating often indicates an excess heat condition; a red tongue with little or no coating, or with cracks on the coating, often indicates a deficiency heat condition. This point will be elaborated on later.
Scarlet tongue. A scarlet tongue is a deeper color than a red tongue, indicating a more severe heat condition. Like a red tongue, it can be caused by either excess heat or deficiency heat, and we need to combine it with the tongue coating for differentiation.
Purple tongue. Purple is a color that combines red and blue. Therefore, a purple tongue can have two meanings. If the red component is more, the tongue appears scarlet purple, often indicating internal heat, with blood being concentrated and stagnant due to heat; if the blue component is more or the tongue is light purple and moist, it often indicates internal cold, with blood being congealed and stagnant due to cold.
Blue tongue. The primary diseases associated with blue color are blood stasis and cold conditions, and blue tongue is no exception. A blue tongue is a color that reflects blood stasis in the tongue, resembling the “blue veins” that protrude on the skin during varicose veins, primarily dark blue and lacking red tones. Therefore, blue tongue symbolizes internal cold and blood stasis, with an entirely blue tongue indicating invasion of cold evil, stagnation of yang qi, and local blood congealing, while blue on both sides of the tongue often indicates internal blood stasis.
By observing the color of the tongue, we can understand the internal conditions of cold and heat, as well as the smoothness of qi and blood circulation. By observing the shape of the tongue, we can understand the internal environment of the body.
The shape of the tongue, refers to the external shape of the tongue, commonly seen as fat, thin, old, young, swollen, or shriveled and certain special pathological conditions.
Fat tongue. A tongue that is larger than normal, filling the mouth, and appears to be full of moisture is called a fat tongue. Due to the enlargement of the tongue, the edges of the tongue often come into contact with the teeth, forming indentations, which is also referred to as “tooth-marked tongue.” It is evident that a fat tongue and tooth-marked tongue are caused by excessive moisture in the tongue body, which is due to excessive accumulation of water and dampness in the body. Therefore, the appearance of a fat tongue and tooth-marked tongue indicates a pathological phenomenon of excessive water and dampness accumulation in the body.
Thin tongue. A tongue that is smaller and thinner than normal is called a thin tongue. In contrast to a fat tongue, a thin tongue indicates a deficiency of yin fluids or insufficient qi and blood, leading to an inability of the tongue body to be full. If the thin tongue is bright red, it indicates a deficiency of yin fluids; if the thin tongue is light white, it indicates insufficient qi and blood.
Old tongue. A tongue with rough texture, lacking moisture, and appearing firm and aged is called an old tongue.In TCM, an old tongue generally represents an excess condition.
Young tongue. A tongue with a delicate texture, more moisture, and appearing plump and tender is called a young tongue.In TCM, a young tongue generally represents a deficiency condition.
Cracked tongue. A tongue surface with varying depths and shapes of cracks is called a cracked tongue.Most often, this is due to diseases consuming the body’s qi, blood, and fluids, leading to the inability of the organ systems to nourish the tongue body, resulting in cracks. However, some normal individuals may also exhibit cracked tongues, so we cannot assume that a cracked tongue always indicates a deficiency of vital energy; it is essential to consider the overall condition of the body.
Pointed tongue. “Pointed” refers to red, white, or black spots that protrude on the tongue surface; “thorny” also known as “thorn prick,” refers to soft spikes and abnormal enlargement of particles on the tongue surface, forming sharp protrusions, resembling thorns.Points and thorns commonly appear at the tip or sides of the tongue, often caused by various heat conditions.
Heavy (pronounced “chong”) tongue. “Heavy” means overlapping, referring to the swelling of blood vessels under the tongue, resembling a small tongue growing beneath the original tongue, hence called a heavy tongue. If multiple blood vessels swell and overlap, resembling a lotus flower, it is also called a “lotus tongue.”Heavy tongue and lotus tongue are both formed by the swelling of blood vessels under the tongue. As previously mentioned, the heart governs blood vessels, and excessive heart fire can lead to over-congestion of blood vessels, resulting in swelling. Therefore, heavy tongue and lotus tongue are primarily associated with excessive heart fire.
In addition to the common changes in tongue shape mentioned above, many diseases of the tongue itself can also lead to changes in tongue shape, such as tongue infections, ulcers, tumors, etc., which will exhibit different changes in tongue shape that need to be identified and judged based on their symptom characteristics.
The state of the tongue refers to the dynamic state of the tongue. Abnormal dynamics of the tongue are often caused by neurological disorders.Common abnormalities in the state of the tongue include stiffness, weakness, deviation, tremor, protrusion, shortening, relaxation, and paralysis, which can be summarized into two categories:
One is hyperactivity of the tongue’s motor function, and the other is weakness or loss of the tongue’s motor function. Hyperactivity of the tongue’s motor function can lead to stiffness, tremors, protrusions, and shortening; while weakness or loss of the tongue’s motor function can result in weakness, deviation, relaxation, and paralysis. Let’s take a closer look at the characteristics of these states of the tongue.
Stiff tongue. A tongue that is stiff and straight, with limited movement, leading to difficulties in eating and slurred speech, is also known as “stiff tongue.” We mentioned in the section on “internal wind” that “all violent stiffness belongs to wind,” so “stiff tongue” in TCM is a manifestation of internal wind.
Weak tongue. A tongue that is weak and lacks strength to move is called a weak tongue.A weak tongue is a result of extreme deficiency of qi, blood, or yin fluids, leading to a lack of nourishment and moisture for the tongue body. The movement of the tongue primarily relies on the tongue muscles, and the strength of the tongue muscles is closely related to the nutritional supply to the tongue. If the body is deficient in qi, blood, or yin fluids, the tongue muscles cannot receive sufficient nourishment, and naturally cannot function well, similar to how we feel weak and limp if we do not eat for several days.
Trembling tongue. A tongue that trembles and shakes involuntarily is called a trembling tongue, also known as “quivering tongue.” Trembling is a characteristic of “wind,” so a trembling tongue is also a primary manifestation of internal wind.
Deviated tongue. A tongue that is tilted to one side is called a deviated tongue, commonly seen in patients with cerebrovascular accidents (cerebral hemorrhage, cerebral infarction).
Protruding tongue. A tongue that is constantly protruding from the mouth is called a protruding tongue; if the tongue slightly protrudes and immediately retracts, or licks around the lips continuously, it is called a licking tongue. When we eat spicy food or burn our tongue with hot water, we often open our mouths wide and stick our tongues out to lower the temperature of the tongue surface and reduce discomfort. The reason for protruding the tongue is similar. It is due to internal heat, causing the tongue to protrude to obtain temporary cooling.Licking tongue, like trembling tongue, also has the characteristic of “wind” and is often seen in internal wind.
Shortened tongue. A tongue that is contracted and cannot extend is called a shortened tongue. The natural property of objects is that they expand when heated and contract when cooled, so the shortening of the tongue is often caused by the invasion of cold evil.
Relaxed tongue. Relaxed refers to the opposite of shortening; a relaxed tongue is one that extends beyond the mouth, with difficulty retracting or unable to retract, also known as “long tongue.” Since cold causes contraction, the reason for a relaxed tongue is naturally heat, so a relaxed tongue is often caused by internal heat; if accompanied by weakness, it is often due to qi and blood deficiency.
Paralyzed tongue. Numbness refers to a lack of sensation, and paralysis refers to stiffness. A paralyzed tongue is one that has limited movement and is accompanied by a numb sensation.If numbness predominates over stiffness, it is often due to qi and blood deficiency, leading to a lack of nourishment for the tongue body; if stiffness predominates over numbness, it is often caused by internal wind.
The impact of diseases on the body is reflected not only in the spirit, color, shape, and state of the tongue body but also leads to various changes in the tongue coating. To understand the significance of the tongue coating in disease diagnosis, we first need to understand how the tongue coating is formed.
The formation of the tongue coating is closely related to the functions of the spleen and stomach. In the holistic study of TCM, the tongue coating is a manifestation of the essence of food and drink (the refined substances formed after the digestion of food by the spleen and stomach) rising to the tongue. Under normal conditions, the coating is neither thick nor dense, and the light red tongue body can be faintly seen beneath it, appearing pale white. In a diseased state, various external evils or internal evils can affect the rise of the spleen and stomach essence, leading to various changes in the tongue coating. These changes can be divided into two categories: color changes and texture changes.
First, let’s look at the color changes.The color changes of the tongue coating are often related to heat, why is that?
We can explain this with an analogy of the food digestion process. When rice and water are heated in a pot, at the right temperature, after a certain time, raw rice becomes cooked rice, which appears a crystalline white color when cooked. If heating continues, the rice will gradually turn yellow and eventually become blackened. The spleen and stomach are the main organs for digesting food in the body. Water and food mix in the stomach (like the pot for cooking), and through the spleen’s transportation and the stomach’s rotting and ripening (like the fire under the pot), food is transformed into the essence of food that the body can utilize (like cooked rice). The essence rises to the tongue surface, showing a thin white and moist color. If the essence is subjected to internal or external heat, it will lead to changes in the tongue coating color to yellow, gray, or black (similar to how cooked rice turns black if heated too long). Since evil heat consumes the body’s fluids, the changes in the tongue coating color will inevitably be accompanied by dryness, roughness, and lack of moisture in texture.
In addition to evil heat, another factor that can cause the tongue coating to appear gray or black is related to the previous discussion on color and the five elements. Can anyone guess what it is? It is water. Black is the pathological color of water, and water has cold properties. Therefore, when internal fire and cold are excessive, or when water and dampness accumulate, the tongue coating can also appear gray or black. Since both heat and cold can lead to gray or black changes in the tongue coating, how do we differentiate between them?
Since heat and cold are completely opposite pathogenic factors, we can differentiate them based on the texture of the tongue coating.Gray or black coating caused by evil heat is necessarily dry and lacks moisture, while gray or black coating caused by cold is moist and watery. This example also shows that besides the color of the tongue coating, the texture of the tongue coating is closely related to the nature of the disease. Only by studying the changes in both the texture and color of the tongue coating can we gain a complete and comprehensive understanding of the nature of the disease. Now, let’s explore the relationship between the texture of the tongue coating and diseases.
The texture of the tongue coating, in addition to the previously mentioned moisture and dryness, also includes thickness, rancidity, and peeling. By observing these changes, we can understand the depth of the evil qi and the strength of the stomach qi.
The moisture and dryness of the tongue coating mainly reflect the status of the body’s fluids. A moist tongue coating indicates sufficient body fluids; a dry tongue coating indicates fluid deficiency. Depending on the degree of fluid deficiency, the degree of dryness of the tongue coating will also vary, and the texture will differ. If the fluids are mildly deficient, the tongue coating appears dry, looking withered and lacking moisture, which in TCM is also called “dry coating.” If the fluids are moderately deficient, the tongue coating appears dry and rough like sand, feeling rough and uneven, which in TCM is called “rough coating.” If the fluids are severely deficient, the tongue coating appears dry and hard, with cracks, resembling land cracking after a drought; this type of tongue coating is referred to as “dry cracked coating.” If the tongue is overly moist, the tongue coating appears slippery and greasy, even drooling, indicating excessive water and dampness in the body; this type of tongue coating is called “slippery coating.”
In addition to the moisture level of the tongue coating, the thickness of the tongue coating also plays a significant role in understanding the nature of the disease.
The thickness of the tongue coating mainly reflects the amount of turbid substances in the body. The normal tongue coating is a thin white layer formed by the upward rise of the essence of food and drink, through which the light red tongue body can be faintly seen. When the disease is mild and shallow, without affecting the spleen and stomach’s digestion of food, the tongue coating is often thin. However, when the disease weakens the spleen and stomach’s ability to transport and digest, leading to abnormal accumulation of turbid substances, these turbid substances rise to the tongue surface, causing the tongue coating to thicken. As mentioned earlier, we often experience this in daily life; when we have indigestion, we often find that the tongue coating becomes thicker, which is the reason. Therefore, thick coating in TCM is often a sign of food stagnation or dampness that is not transformed.
How do we determine if the tongue coating is thick? How do we distinguish it from normal thin white coating? The standard for distinguishing thick coating from thin coating is whether we can “see the bottom.” The so-called “seeing the bottom” means that we can faintly see the tongue beneath the coating. If we cannot see the tongue body beneath the coating, we call it thick coating. Thick coating can be further classified based on the coarseness of the particles and the fineness of the texture into rancid and greasy types. Thick coating with coarse and loose particles, like tofu residue on the tongue surface, which can be scraped off, is called “rancid coating”; if the thick coating has fine and dense particles, cannot be scraped off, and is covered with a greasy layer, it is called “greasy coating.” Rancid coating primarily reflects the presence of turbid substances (such as undigested food stagnation, putrefactive substances from ulcers, etc.) on the tongue surface, while greasy coating reflects excessive water and dampness on the tongue surface.
Finally, let’s look at the peeling of the tongue coating.Complete or partial loss of the tongue coating, revealing a smooth tongue body, is referred to as peeling of the tongue coating. Depending on the extent of the peeling, TCM has different names for it. If the tongue coating completely disappears, and the tongue surface appears smooth like a mirror, it is called “mirror tongue” or “glossy tongue”; if the tongue coating is partially peeled, with smooth areas without coating and other areas still retaining the coating, forming a red and white “flower” pattern, this type of tongue coating is called “flower peeling coating.” As mentioned earlier, the normal tongue coating is a manifestation of the body’s essence of food and drink on the tongue surface, and the formation of this essence relies on the spleen and stomach’s ability to transport and digest food. Therefore, the peeling of the tongue coating symbolizes damage to the spleen and stomach’s essence, indicating that the essence of food and drink cannot rise to the tongue surface. Particularly, “glossy tongue” is a sign of extreme depletion of the spleen and stomach’s essence, indicating a severe or critical condition that requires special attention.
By combining the color and texture of the tongue coating, we can more comprehensively assess the nature of the disease’s cold and heat, the strength of the spleen and stomach’s essence, and the amount of turbid substances in the body. Common types include:
Thin white coating. This is the normal type of tongue coating. If the disease is mild and shallow, without affecting the normal function of the spleen and stomach, the body often exhibits this type of coating.
White thick coating or white rancid coating. Rancid coating and thick coating both reflect the presence of turbid qi on the tongue surface, while white indicates the absence of heat or the presence of internal cold. Therefore, white thick coating or white rancid coating reflects the body’s weak yang qi, internal dampness, or food stagnation.
Yellow greasy coating. Yellow reflects heat, and greasy symbolizes dampness. Therefore, yellow greasy coating indicates a condition of “damp-heat” in TCM. The formation of damp-heat is often closely related to the functions of the spleen and stomach and the composition of the diet. Nowadays, with improved living conditions, the increased intake of high-fat and high-protein foods can affect the normal transportation and digestion functions of the spleen and stomach, leading to the accumulation of undigested turbid substances—phlegm-dampness. When phlegm-dampness accumulates over time, it can generate heat, similar to how a pile of garbage will ferment and produce heat if not dealt with for a long time. This combined state of dampness and heat is referred to as “damp-heat.” Since phlegm-dampness is also a major cause of obesity, yellow greasy coating is more common among overweight individuals.
Thin yellow coating. The coating color turns yellow, while the texture remains thin. Yellow indicates heat, and thin coating suggests that the evil qi is superficial, without affecting the spleen and stomach, and no turbid substances are accumulating in the body. Therefore, thin yellow coating often indicates heat at the muscle level (such as fever from a cold, soft tissue infections, etc.).
Changes in the color and texture of the tongue coating are important indicators for assessing the nature of diseases, the strength of the spleen and stomach’s essence, and the amount of turbid substances in the body. However, when observing the tongue coating, it is essential to note that the coating used as a basis for judgment must genuinely reflect the disease. What does this mean? Can the tongue coating be faked? Yes, the tongue coating can also be artificially altered. Consuming certain foods or medications containing pigments or special textures can lead to changes in the color and texture of the tongue coating, creating various illusions. This type of tongue coating is referred to as “dyed coating.” For example, drinking milk or newborns sucking breast milk can create a false appearance similar to white coating; consuming peanuts, sunflower seeds, almonds, or soybeans rich in plant fats can temporarily leave white residues on the tongue, resembling rancid coating; drinking coffee, grape juice, alcohol, or various iron-containing supplements can often dye the tongue coating black or brown; consuming egg yolks, vitamin B2, persimmons, oranges, or colored candies can often dye the tongue coating yellow; taking medications containing cinnabar can often dye the tongue coating red; etc. If we use these dyed coatings as a basis for disease diagnosis, we will make significant errors, as dyed coatings are merely the influence of external pigments on the tongue coating, not a reflection of the disease.
In addition to the changes in color and texture of the tongue coating reflecting the nature and depth of diseases, the location of the tongue coating on the tongue surface also holds significant diagnostic importance. TCM divides the tongue into three parts: the tip, the middle, and the root, corresponding to the three burners of the body. Specifically, the tip corresponds to the upper burner, the middle corresponds to the middle burner, and the root corresponds to the lower burner. Abnormal tongue coatings appearing in different areas reflect diseases in different locations. For example, if the middle of the tongue has a greasy coating, it indicates that dampness is retained in the middle burner (such as the spleen and stomach); if the root of the tongue has a greasy coating, it indicates that dampness is retained in the lower burner (such as the bladder and kidneys), etc. Since the five organs correspond to the three burners, we can also associate the five organs with different parts of the tongue. For instance, the heart and lungs belong to the upper burner, so they correspond to the tip of the tongue; changes at the tip can reflect the condition of the heart and lungs; the spleen and stomach belong to the middle burner, so they correspond to the middle of the tongue; changes in the middle can reflect the condition of the spleen and stomach; the kidneys and bladder belong to the lower burner, so they correspond to the root of the tongue; changes at the root can reflect the condition of the kidneys and bladder; etc. By understanding the correspondence between the five organs and different parts of the tongue, we can assess the disease status of the five organs based on the changes in the tongue body and tongue coating, providing another basis for disease diagnosis.
The content of this article is for reference only, and non-professional doctors should not attempt acupuncture or medication.