A healthy tongue has a white-transparent coating (like "velvet") slightly moist that allows seeing the color of the tongue body.

The coating or tongue coating reflects:

• State of the vital energy of the Stomach.
• Pathogenic energy.

The coating forms from the functional energy of the Stomach, to which the energy of the five organs arrives. Hence why cold, heat, excess or deficiency can be differentiated in the coating.

To differentiate the coating two steps should be observed:

• 1 - Nature: with or without coating, thick or thin, dry, slippery or sticky, etc.
• 2 - Color: Yellow, white, black, etc.

Nature of the coating

Without Coating or with "rootless" coating

• Tongue without coating: May lack coating all over the tongue or in areas, shows Yin Deficiency and/or Blood Deficiency. This type of tongues shines like a piece of raw chicken breast without skin.
• Tongue with rootless coating: The coating seems not to grow from the tongue, as if they were "separated". It is a sign of Stomach-Qi Deficiency.

Coating Thickness

If the coating is thin, it allows seeing the tongue body underneath. Thick coating is spongy and with large grains like the appearance of "cheese".

Thick Coating

It resembles a membrane or literally a thick layer.

• Thick and purulent: Phlegm-Heat in the Lungs or Phlegm-Cold in the Lungs
• Thick and gray-purple: Hepatic abscesses
• Thick, sticky and yellow: Poor circulation due to Dampness, Phlegm combined with Heat or epidemic problems.
• Thick, sticky and white: Poor circulation due to Dampness and Cold.
• Thick and dry: Internal lesion due to an epidemic factor associated with Dampness. (Like wheat flour)

Evolution of diseases

Observing the coating thickness gives us information about disease evolution. Cold, Heat and Fire and Wind are associated and penetrate slowly into the body.

• Coating becoming thick: Pathogens are inside and gather with the "turbidity" of the Stomach. Color may change from white to yellow and then to black.
• Coating becoming thin: The pathogenic factor tends to disappear.

Dryness of the coating

The tongue naturally secretes saliva, so it is slightly moist. Excess saliva will cause a moist and slippery coating; A deficiency of saliva will cause a dry coating.

Moist tongue coating

The main cause is dampness and cold. Remember that Yang deficiency causes both cold and dampness.

• Slightly moist and thin coating: Body Fluids in good condition.
• Moist coating: Dampness syndrome
• Moist and slippery coating: It is a symptom of Cold or Yang Deficiency and Dampness. Seen with excess saliva, even a transparent layer of saliva is found on the coating.
• Slippery and sticky coating: Means Dampness - phlegm.
• Slippery, sticky and thick coating: Means Dampness - phlegm and Cold.

Dry tongue coating

Mainly found in syndromes of internal or external heat that cause internal dryness.

• Dry and rough coating: Body Fluids have been consumed.
• Dry coating: Heat syndrome.
• Dry and yellow coating: Excess heat internal, especially Stomach Heat.
• Dry and black coating: Syndrome of Yin exhaustion due to excess heat. Also in cases of phlegm heat in the chest.
• Dry, black and thick coating: Mainly when found in the center of the tongue is due to Dryness of Spleen and Kidney-Yin Deficiency

Seborrheic or rotten tongue coating

• Seborrheic: Does not disappear when cleaning with a brush. Indicates pathogenic energy accumulated inside.
• Rotten: As if it had mold, you brush it and it disappears. It is a non-rooted coating. On one hand it indicates contamination, pathogenic energy and heat. But when removed, the patient has no coating, has a red tongue. Indicates exhaustion of the energy of Stomach of Earth. It is serious.

Color of the coating

In a first general reading:

• White coating: Indicates an exterior syndrome or Cold syndromes.
• Yellow coating: Indicates a pattern of heat or that the external pathology has penetrated inside and transformed into heat.

White Coating

As a general rule it is a pathology of the Lungs or Large Intestine. Secondly it is seen in external pathologies in the Tai Yang Layer Finally it indicates Cold.

• Thin white coating: Attack of Wind, Cold and Dampness on the body surface. Tai Yang Layer.
• Thin, white and slippery coating: Cold and Dampness damage the body surface.
• Thin, white and dry coating: Qi Deficiency and body fluid deficiency or also problem of the lungs due to Dryness
• Moist white and somewhat thick coating: Wind and Cold in excess; External pathogenic energies that are penetrating the body. Also cold-dampness in the Middle Burner.
• White, thick and sticky coating: Stagnation of Dampness or food.
• White, thick, sticky and slippery coating: Stagnation of Cold, Dampness and Phlegm.
• White, sticky and dry coating: Problems with Body Fluids due to stagnation of Dampness. Dampness stagnation generates heat
• White, rough and cracked coating: Heat damaging Body Fluids. Summer heat also damages Qi.
• White, sticky and mucous coating: Phlegm-Dampness. Damp-heat in the Middle Burner. Dampness stagnation in the Qi Layer
• White coating like wheat flour: Heat pathogen. Excess toxic heat, especially in the Triple Burner.
• Coating resembling "snowflakes": Exhaustion of Spleen Yang
• Coating like "Mold": Stomach-Yin Deficiency and Kidney-Yin Deficiency.

Yellow Coating

As a general rule yellow coating reflects a pathology of Spleen or Stomach. Secondly it is seen in interior pathologies like the Yang Ming Layer. And finally, it appears in cases of Heat by excess.

• Light yellow coating: Wind and Heat on the body surface or wind and Cold that turn into heat.
• Slippery yellow coating: The pathogenic heat begins to internalize: Yang Ming Layer
• Yellow and turbid coating: Excess Dampness and Heat inside.
• Yellow and sticky coating: Dampness and Heat with Phlegm.
• Yellow and dry coating: The external pathogen penetrates into the body. If it is the case that heat lowers the fluids they have not yet recovered. Excess Heat inside.
• Yellow coating at the root and white at the tip: External pathogenic energies turn into heat to penetrate inside.
• Yellow coating at the tip and white at the root: Heat in the Upper Burner.
• Yellow coating on the sides: External pathogenic energies are penetrating but exterior symptoms still do not disappear. Stomach Heat and in the intestines.
• White coating on one side and yellow on the other: Heat stagnation in Liver and Gall Bladder.

Black Coating

• Gray-black and thin coating: Cold in the Middle Burner.
• Gray-black, slippery and sticky coating: Cold, Phlegm and Dampness. Also Dampness, Phlegm and Heat stagnated.
• White coating with black coating on the sides: Cold-Dampness in the Middle Burner or excess Stomach Heat and Spleen.
• White coating with black spots: External factor that turns into heat and enters the organism. Internal excess of Damp-Heat.
• White coating with black spines: True cold and false heat.
• Black coating in the center with white coating on the sides: Yang Deficiency, Cold and Dampness.
• White, slippery coating on one half and black and yellow on the other: Heat that has accumulated in Liver and Gall Bladder.
• Black coating in the center with yellow coating on the sides: Damp-heat in Spleen and stomach.