1. Normal Tongue Appearance
Normal Tongue Appearance: The tongue body is soft, flexible, light red in color, and covered with a thin, evenly distributed, moderately moist white coating, often described as “light red tongue with thin white coating”.
Observing the tongue mainly involves examining changes in tongue quality and tongue coating. The tongue quality, also known as the tongue body, is the muscular and vascular tissue of the tongue.
The so-called “stomach qi” refers to the healthy transformation of the spleen, with the stomach being responsible for receiving and digesting (indicating normal digestive function). When the physiological functions of the spleen and stomach are normal, a thin and moist tongue coating can be observed. During pathological changes in the body, the fluctuations of yin and yang, the harmony of qi and blood, and the preservation of body fluids can all be directly reflected in changes in the tongue coating. By observing changes in the tongue coating, one can infer the condition of the internal organs (organ dysfunction) and the severity of disease (the progression of illness).
The tongue coating is a layer of coating attached to the tongue body, generated by stomach qi.
2. Cracked Tongue
Illustration: Cracked Tongue: The tongue surface shows various cracks of different depths and shapes, referred to as cracked tongue.
Cracked tongue indicates: (1) Excess heat injuring yin, often seen as a red tongue with cracks; (2) Blood deficiency leading to lack of moisture, often seen as a pale white tongue with cracks; (3) Spleen deficiency with dampness, often presenting as a pale, plump tongue with teeth marks and cracks. Treatment should focus on nourishing yin essence, benefiting qi, and generating fluids; tonifying the spleen and draining dampness; nourishing yin and clearing heat; clearing heat and moistening dryness.
Additionally, cracked tongue refers to cracks in the tongue body as well as cracks in the tongue coating; during diagnosis, one should differentiate based on the dryness or moisture of the coating. If the cracks are due to dryness, it indicates an external pathogenic disease with heat injuring fluids, leading to severe dryness. If the coating has moisture and cracks, it is often due to qi deficiency.
3. Enlarged Tongue
Illustration: Enlarged Tongue: The tongue body appears swollen and enlarged, or has teeth marks on the edges, pale and tender in color, referred to as an enlarged tongue.
Main diseases and related studies: An enlarged tongue has also been discussed in ancient texts in relation to a swollen tongue. In fact, an enlarged tongue is caused by deficiency of the spleen’s yang qi, or combined with cold dampness, leading to a swollen, tender, pale tongue, often with teeth marks, indicating a deficiency, and should be distinguished from a swollen tongue.
4. Teeth-marked Tongue
Illustration: Teeth-marked Tongue: The edges of the tongue show impressions from the teeth, known as a teeth-marked tongue.
Teeth-marked tongue is often caused by the tongue body being enlarged and pressed by the teeth, thus it is often seen together with an enlarged tongue, mostly indicating spleen deficiency, representing a deficiency syndrome. If the tongue quality is pale and moist, it indicates spleen deficiency with cold dampness.
Causes of teeth-marked tongue: Often due to spleen deficiency failing to transform and transport fluids, leading to dampness obstructing the tongue, causing it to enlarge and be pressed by the teeth, hence teeth marks are often seen together with a plump tongue. On one hand, this is due to tongue edema, indicating spleen yang deficiency and excess dampness; on the other hand, it is due to relaxation of the tongue muscles, insufficient opening of the mouth, indicating spleen qi deficiency.
5. Thin White Coating
Illustration: Thin White Coating: A thin white coating covers the tongue surface, evenly distributed and moderately moist.
Main diseases and related studies: Thin white coating, with a light red and moist tongue color, is the most common tongue coating under normal conditions, indicating “stomach qi”.
The formation of thin white coating is mainly due to the comprehensive effects of chewing, swallowing, and saliva in the oral cavity, which continuously removes and sheds substances between the filiform papillae of the tongue mucosa and the keratinized epithelium, resulting in only a thin white layer of coating on the tongue.
6. Thin White Dry Coating
Illustration: Thin White Dry Coating: The white coating is thin on the tongue surface, with less fluid and a tendency to be dry.
Main diseases and related studies: Thin white dry coating is due to damage to the lung’s fluids and qi, where qi deficiency leads to insufficient fluid transformation, and less fluid results in a dry tongue coating.
Main diseases often include wind-heat invading the lungs, pathogenic factors injuring the lungs, or yang deficiency failing to transform fluids, leading to damage to both lung qi and fluids; the former should clear and moisten, using Yin Qiao San to nourish yin, clear heat, and generate fluids; the latter should benefit qi and generate fluids, using methods like Xuan Fei Yi Qi Tang to raise yang and benefit qi.
7. Thick White Greasy Coating
Illustration: Thick White Greasy Coating: The tongue shows a white coating that is thick, with tightly packed or loose granules, which can cover the entire tongue or be thinner at the edges.
Main diseases and related studies: Thick white greasy coating is often due to insufficient yang qi in the middle jiao, leading to food stagnation, or due to damp phlegm accumulation.
According to the “Guide to Tongue Diagnosis”: “White greasy coating, chest oppression and pain, irritability and dry retching; often wanting to drink water, but vomiting upon drinking, indicates heat due to drinking stagnation, should use pungent and light methods to transform the drink.”
Thick white greasy coating indicates: dampness, phlegm, and cold.
8. White Coating with Dry Cracks
Illustration: White Coating with Dry Cracks: The coating is white, can be thin or thick, with rough and loose granules, dry and hard, resembling sand or stone, and if the granules are finer and hard, with transverse and longitudinal cracks, it is referred to as white coating with dry cracks.
Main diseases and related studies: White coating and dry cracks can appear simultaneously on the tongue surface, hence collectively referred to as white coating with dry cracks.
Both are caused by internal heat rising violently, leading to severe damage to fluids. This is often seen in acute warm diseases, where heat rises violently, damaging fluids, and true yin is about to deplete, while the coating has not yet turned yellow; if the coating is white and cracked but not too dry, it is often seen in summer heat, where summer heat injures qi, with internal dampness and turbidity.
9. Yellow Greasy Coating
Illustration: Yellow Greasy Coating: The tongue shows a yellow and greasy coating, with tightly packed granules, resembling a yellow powder applied to the tongue surface.
Main diseases and related studies: Yellow greasy coating is formed by the combination of pathogenic heat and phlegm-dampness. Yellow coating indicates heat, while greasy coating indicates dampness, phlegm, or food stagnation.
Yellow greasy coating indicates: accumulation of damp-heat, phlegm-heat transformation, or food stagnation transformation into heat; also indicates external pathogenic summer heat, damp-warmth, etc. Treatment should focus on clearing heat, transforming dampness, and eliminating phlegm. Additionally, when diagnosing yellow greasy coating, one should also consider the quality of the tongue.
10. Yellow Dry Coating
Illustration: Yellow Dry Coating: The tongue shows a yellow coating that is dry and has little fluid (liquid), indicating a pathological change due to heat injuring fluids.
Main diseases and related studies: Yellow dry coating indicates: internal heat transmission, treatment should directly clear heat from the interior. When heat is excessive in the qi level, leading to fluid damage, one should use pungent and cold methods to clear heat and preserve fluids. In cases of excess heat in the interior, one should use bitter and cold methods to purge heat and rescue yin. Since yellow dry coating often combines with complex main diseases, medication should also be determined based on the condition.
11. Yellow Coating
Illustration: Yellow Coating is a common pathological tongue coating, which can also be seen in some healthy individuals. The yellow coating seen in healthy individuals is mainly thin yellow coating or thin yellow greasy coating. Thick yellow greasy coating increases with age.
Yellow coating indicates: diseases of the spleen and stomach, interior syndrome, and heat syndrome. The “Comprehensive Guide to Tongue Diagnosis – Overview of Yellow Coating” states that yellow coating can be present in both excess heat syndromes and deficiency cold syndromes. Pathogenic heat scorching leads to yellow coating, with light yellow indicating mild heat; deep yellow indicating severe heat; and burnt yellow indicating heat accumulation. In cases of external pathogenic diseases, the tongue coating changes from white to yellow, indicating that the exterior pathogen has entered the interior and transformed into heat; in typhoid fever, it belongs to the yangming level; in warm diseases, it belongs to the qi level.
However, yellow coating can also be seen in exterior syndromes and deficiency cold syndromes: if the coating is thin white with light yellow, it indicates wind-heat exterior syndrome or wind-cold transforming into heat; if it is light yellow with thick coating, it indicates chest damp-heat, qi stagnation; if the tongue is plump and tender with yellow coating, it indicates yang deficiency with water retention transforming downwards. Therefore, yellow coating in the interior is a basic indication but not absolute.
12. Thin Yellow Coating
Illustration: The tongue has a yellow coating, thin yellow coating is a light yellow coating mixed with thin white coating.
Main diseases and related studies: Thin yellow coating is a common pathological tongue coating, which can also be seen in some healthy individuals. The common yellow coating is mainly thin yellow coating or thin yellow greasy coating. Thick yellow greasy coating increases with age.
Thin yellow coating often develops from white coating, indicating that the disease has transformed from cold (cold among the six excesses) into heat, moving from the exterior to the interior (indicating worsening of the condition or prolonged illness).
13. Gray Coating
Illustration: Gray Coating: The tongue shows a grayish-black coating.
Main diseases and related studies: Gray coating indicates: dryness, often associated with yangming organ excess, where yin fluids have been damaged; if there is excess in the organ, treatment should directly use bitter and cold methods to purge; if there is no excess in the organ, with a fine and rapid pulse, treatment should focus on bitter and cold methods to rescue fluids.
If gray coating is greasy, it indicates phlegm-dampness obstructing the interior, often seen in warm diseases combined with phlegm-dampness, or accompanied by other severe symptoms, requiring careful differentiation.
Treatment should focus on warming the middle, drying dampness, and using aromatic methods to clear. If gray coating is moist and slippery, with a fine pulse, it indicates yang deficiency with cold symptoms, requiring warming yang and dispelling cold, such as using Si Ni San or Li Zhong Wan.
Additionally, gray coating indicates different conditions of cold, heat, and dampness, and clinical diagnosis should also consider tongue quality, moisture, and other symptoms.
14. Burnt Yellow Coating
Illustration: Burnt Yellow Coating: The tongue shows a deep yellow and burnt coating, or thick and dark yellow, especially at the center or root of the tongue.
Main diseases and related studies: Burnt yellow coating indicates internal heat accumulation in the stomach. According to “Tongue Diagnosis in Traditional Chinese Medicine”: “Yellow and dry indicates damage to stomach fluids; burnt yellow and cracked indicates severe heat; deep burnt yellow indicates extreme heat, requiring urgent treatment; yellow and dry with black tips indicates intestinal decay.”
15. Pale White Tongue with Insufficient Fluids
Illustration: The tongue shows insufficient fluids, or even no fluids.
Main diseases and related studies: Pale white tongue with insufficient fluids is often due to yang qi deficiency, which fails to generate and transform fluids, or yang deficiency leading to water retention, causing fluids to be unable to nourish the tongue.
The tongue color is pale white with insufficient fluids, as fluids are transformed from the essence of food through the warming action of yang qi, and then distributed throughout the body by yang qi. If the middle and upper jiao’s spleen and lung yang qi are weak, the spleen yang cannot generate fluids, and the lung qi cannot distribute fluids.
For patients with water retention in the abdomen, the mouth and tongue may appear dry, indicating a syndrome. Yang deficiency fails to transform water into fluids, nourishing the orifices, and fails to distribute fluids, leading to a pale white tongue with insufficient fluids.
Pale white tongue with insufficient fluids indicates: yang qi deficiency, insufficient fluids. Treatment should focus on tonifying yang, benefiting qi, and generating fluids to moisten dryness.
16. Pale White Tongue with Stasis
Illustration: The tongue has a thin white coating, with pale white tongue quality and stasis spots.
Main diseases and related studies: Pale white tongue with stasis: Previous literature has rarely discussed pale white tongue with stasis (spots, dots), but clinically, this tongue appearance does exist. Analyzing its formation, it is often related to blood deficiency combined with stasis. Modern microcirculation studies of the tongue have found that pale white tongue indicates insufficient filling of microvessels within the filiform papillae.
Additionally, slow blood flow and narrowed vessel diameter can lead to local blood stasis, causing red blood cells to aggregate, resulting in pale white tongue with stasis spots or dots on the edges.
Main diseases: qi deficiency with blood stasis, blood deficiency with blood stasis.
17. Pale White Glossy Tongue
Illustration: The tongue is pale white, with all the coating completely shed, smooth like a mirror, resembling freshly peeled chicken skin.
Pale white glossy tongue is due to damage to the spleen and stomach, with both qi and blood deficiency, unable to recover for a long time, leading to malnutrition, causing the tongue quality to lack sufficient nourishment, resulting in the gradual shedding of the tongue coating without new coating growth, leaving the entire tongue pale white and glossy.
Additionally, one should differentiate pale white glossy tongue from pure white tongue and pale white transparent tongue.
18. Pale White Moist Tongue
Illustration: Pale White Moist Tongue: The tongue is pale white, moist, or has abundant fluids.
Main diseases and related studies: The former pale white tongue indicates qi and blood deficiency, with the tongue body being normal or slightly small. Qi deficiency fails to generate blood, or blood deficiency leads to qi deficiency, ultimately resulting in both qi and blood deficiency.
This prevents nourishment to the tongue surface, often due to prolonged illness or excessive blood loss. Treatment should focus on tonifying both qi and blood, using formulas like Shi Quan Da Bu Tang to gradually achieve results.
The latter moist tongue indicates spleen deficiency with cold dampness, with a plump tongue body and teeth marks on the edges, often due to spleen yang deficiency, where the spleen fails to transform and transport fluids, leading to dampness infiltrating the tongue, resulting in a moist and plump tongue. Treatment should focus on warming the spleen, assisting yang, and dispelling cold dampness.
19. Bright Red Cracked Tongue
Illustration: The tongue is bright red, with cracks resembling a human character or other shapes.
Main diseases and related studies: Bright red cracked tongue indicates heart fire scorching, heat toxin steaming; if the tongue is deep red with uneven white coating or no coating, with many cracks resembling deep grooves, it often indicates bright empty fire, insufficient fire, or true yin depletion. If the cracks appear in the shape of “人” or “川”, or as straight grooves, it indicates excess heat injuring fluids, burning stomach fluids, or kidney water attacking the heart.
Bright red cracked tongue indicates: yin deficiency with heat, evil entering the blood and nutrients, insufficient stomach yin, phlegm-heat congealing. Treatment should focus on clearing the heart, draining heat, nourishing yin, and generating fluids.
20. Bright Red Tongue with White Spots
Illustration: The tongue is bright red, with scattered white spots on the surface, raised above the tongue surface, indicating severe heat toxin, a sign of impending ulceration of the tongue.
Main diseases and related studies: Bright red tongue with white spots is due to spleen and stomach qi deficiency, unable to withstand the attack of heat toxins.
Bright red tongue with white spots indicates: severe heat, spleen and stomach qi deficiency allowing heat toxins to attack; treatment should focus on clearing heat, defeating toxins, and nourishing the stomach while clearing heat.
21. Old Tongue
Old tongue is often due to excessive pathogenic factors, with the righteous qi not declining, hence the tongue is firm and pale.
According to the “Clinical Tongue Examination Method – Examination of Tongue for Deficiency and Excess”, it is believed that for any substance, if it is firm, it indicates excess; if it is soft, it indicates deficiency.
Moreover, if the qi is still young, the quality is still tender, and the qi is abundant, the quality is firm.
Therefore, regardless of tongue color or coating, a firm and pale tongue indicates an excess syndrome.
Additionally, excessive heat leads to qi and blood being blocked above, with a fierce struggle between righteous and evil, causing the tongue to appear firm and pale, hence often indicating an excess heat syndrome.
22. Bright Red Dry Tongue
Main diseases and related studies:
According to “Tongue Diagnosis and Differentiation”: “A tongue that is bright red and lacks fluids, with the entire tongue being bright red, soft and tender but without fluids, appearing moist but actually dry and desiccated, indicates yin deficiency with excessive fire.”
In cases of external pathogenic diseases, when heat evil enters the interior, the nutrients are damaged, and fluids are robbed, this tongue appearance can be observed.
It may also occur in internal injuries, where the body constitution is deficient in yin, with prolonged illness leading to both qi and blood deficiency, causing fluids to be unable to distribute, resulting in a tongue that is bright red and dry.
If only the tip of the tongue is bright red and dry, while the rest is light red, it indicates a sign of excessive heart fire.
