bubble_chart Concept

The yellow coating on the tongue is called "tongue coating yellow," or "fetal jaundice of the tongue," or "yellow coating."

As early as Neijing , there is a record of "yellow on the tongue." Previous discussions on tongue inspection often confused the tongue and its coating, referring to "yellow on the tongue" or "yellow color seen on the tongue," which actually refers to the yellow color of the coating, not the tongue's color.

When clinically examining yellow coating, it is important to distinguish the texture of the coating, such as thickness, thinness, moistness, dryness, curdiness, and greasiness. It is also necessary to differentiate stained coating from other illusions, such as the consumption of egg yolks, persimmons, oranges, colored candies, and other foods, as well as the intake of Coptis Rhizome powder and Chinese medicinal decoctions, which can cause the tongue coating to appear yellow. Seasonal climate influences can also affect the tongue coating, with thin and light yellow coating often seen in summer. People who habitually drink alcohol often have a turbid yellow coating, while heavy smokers may have a yellow coating with a slight black halo, all of which should be distinguished from pathological yellow coating. Diagnosing the tongue under light at night can easily make yellow coating appear as white coating.

Yellow tongue coating combined with changes in tongue texture is not within the scope of this discussion.

bubble_chart Pattern Analysis

1. Yangming Channel Heat︰The tongue coating is yellow, the body has high fever, but there is aversion to heat rather than aversion to cold, profuse sweating, a red face with restlessness, unquenchable thirst, and a surging pulse. This is caused by cold pathogens transforming into heat and entering the interior, or warm disease pathogenic heat entering the qi aspect, leading to excessive yangming stomach heat, hence the yellow tongue coating. It belongs to the yangming meridian pattern, characterized by high fever, profuse sweating, intense thirst, and a surging pulse as key diagnostic points. Treatment should focus on {|###|}clearing heat and promoting fluid production{|###|}, using the formula White Tiger Decoction.
2. Stomach and Intestine Excess Heat︰The tongue coating is deep yellow, thick, and dry, or even old yellow, scorched, cracked, and prickly. The face is red, and the body is hot, with late afternoon tidal fever, thirst, continuous sweating, severe constipation, or watery diarrhea. There is abdominal distension, fullness, and pain that resists pressure, restlessness, delirious speech, or even unconsciousness, or floccillation. The pulse is deep and strong, or slippery and solid. This is due to the unresolved pathogenic heat in the Yangming channel, which has entered the stomach and intestines, binding with dry stool in the intestines and accumulating in the stomach and intestines. Hence, the tongue coating is deep yellow, thick, and dry, or even old yellow, scorched, cracked, and prickly. The key diagnostic features include severe constipation, or heat retention with watery discharge, passing foul-smelling clear water, a burning sensation in the anus, late afternoon tidal fever, abdominal distension and pain that resists pressure, profuse sweating, occasional delirious speech, and a deep, solid pulse. The treatment principle is to purge dryness accumulation, and the recommended formula is the Chengqi Decoction class.
3. Dampness-heat of Spleen and Stomach︰The tongue coating is yellow and greasy, the tongue texture is red, with hidden fever, irritability, thirst without desire to drink, epigastric and abdominal distension and fullness, poor appetite, nausea and vomiting, greasy and foul-smelling stools, and a slippery and rapid pulse. The syndrome arises from exposure to dampness pathogens that linger and transform into heat internally, or from habitual consumption of spicy, hot, and rich foods that promote dampness and accumulate heat. Alternatively, it may result from retained food in the stomach, where dampness-heat and turbid filth combine with stale residues in the stomach and rise to the tongue, manifesting as a yellow and greasy tongue coating. Associated symptoms include chest tightness, gastric stuffiness, nausea and vomiting, hidden fever, and greasy stools, indicating internal congestion of dampness-turbidity and dysfunction of the spleen and stomach’s ascending and descending functions. Treatment should focus on clearing heat and resolving dampness, dispelling turbidity, and eliminating stagnation. Recommended formulas include Immature Orange Fruit Stagnation-Removing Pill and Heart-Draining Decoction.

Stomach heat exuberance and gastrointestinal excess heat with yellow tongue coating both result from pathogenic heat invading the Yangming stomach and intestines. The "Chinese Medicine Tongue Inspection" states: "As for a dry, yellow coating that thickly covers the entire tongue, it is undoubtedly an interior heat pattern."

In summary, a yellow coating is a manifestation of interior, excess, and heat pattern. As the "Shanghan Shejian" says: "A yellow coating indicates an interior pattern... In Yangming fu-organ excess, stomach fire is exuberant, and fire overwhelms the earth position, hence this coating." The three aforementioned patterns are: one, Yangming heat at the qi aspect pattern, characterized by pathogenic heat without form, with a slightly dry yellow tongue coating; two, pathogenic heat transmitted through the channels combined with tangible excess pathogens in the stomach and intestines, forming a Yangming fu-organ pattern, characterized by a dry, yellow, or scorched and prickly tongue coating; and three, heat toxin and damp turbidity stagnating in the spleen and stomach, characterized by a yellow and turbid tongue coating, like "alkali powder spread on the tongue, dark yellow and thick" ("Chinese Medicine Tongue Inspection"). These three should be differentiated based on changes in the tongue coating and symptomatic characteristics, and should not be confused.

Additionally, the "Shejian Bianzheng" states: "A tongue coating appearing over the entire tongue indicates heat in both the zang and fu organs; appearing in a specific area indicates heat in that corresponding channel. This method of differentiating exterior and interior pattern is an unchanging principle." This explains that a yellow tongue coating is not limited to Yangming heat pattern; any heat in other zang or fu organs can also manifest a yellow coating. For example, the "Cold-Damage Disease Ben Zhi" states: "A thin, pale yellow coating indicates heat in the lungs, which has not yet entered the stomach." Clinically, the color and location of the yellow coating can be used for differentiation. For instance, a yellow coating limited to the tongue edges indicates severe liver-gallbladder heat; a yellow coating at the tongue root indicates heat in the lower energizer; and a yellow coating at the tongue tip indicates heat in the upper energizer, and so on.

bubble_chart Documentation

1. 《Four Examinations Juwei · Inspection》: "Shen'an said, in my experience, I have seen tongues with a turmeric-colored coating and a pale pine-flower-colored coating, both moist and cold, which are signs of yang decline and spleen failure, and are certainly incurable. These are conditions that the ancients did not mention, so I have supplemented and recorded them."
2. 《Guide to Tongue Diagnosis》: "If the tongue coating is white with a hint of yellow, or slightly yellow and thin, it indicates that the pathogen has just entered the Yangming channel, still accompanied by superficial symptoms, with slight aversion to cold, and it is appropriate to cool and disperse it. If the coating is yellow and dry, with external symptoms not showing aversion to cold but instead aversion to heat, it indicates that the external pathogen of cold-damage disease has just entered the interior of the Yangming channel, or that the internal pathogen of warm-heat is about to exit the surface of the Yangming channel. At this time, the gastrointestinal system is hot but not yet solid, and it is appropriate to use remedies like Gardenia and Fermented Soybean White Tiger Decoction to clear it."