bubble_chart Concept

The tongue has a coating, and the surface of the coating lacks body fluids. The coating texture is dry, or the tongue is smooth without coating, appearing withered and dry to the eye, and feeling rough and dry to the touch, which is called "dry tongue."

This condition is different from "smooth tongue," where the tongue is smooth without coating, with or without moisture. The identification of a smooth tongue should be combined with tongue texture, while the identification of this condition mainly depends on the abundance or deficiency of body fluids on the tongue surface.

People with a stuffy nose and those who breathe through their mouth often have a dry tongue surface, and this should be distinguished.

A dry tongue is often accompanied by thirst and is referred to as "dry mouth and tongue." This section should be cross-referenced with the "thirst" entry.

bubble_chart Pattern Analysis

1. Yang Exuberance Scorching Fluids︰Dry tongue, yellow and dry or scorched and prickly tongue coating, high fever, flushed face, dysphoria, thirst with a preference for cold drinks, profuse sweating, constipation, yellow urine, and a surging, rapid pulse. This condition is often caused by excessive pathogenic heat scorching body fluids during the course of external-contraction febrile disease, leading to a dry tongue. As stated in *Cold-Damage Disease Treatise on the Essence*: "Dryness indicates pathogenic heat damaging fluids." Clinical manifestations vary depending on the zang-fu organs invaded by pathogenic heat. For example, when pathogenic heat congests the lungs, the main symptoms are high fever, cough, dyspnea, irritability, thirst, and expectoration; when heat is in the qi aspect, the main symptoms are intense fever, profuse sweating, extreme thirst, and a surging, large pulse; when heat accumulates in the stomach and intestines, the main symptoms include tidal fever, constipation, abdominal distension and fullness, and a replete pulse; when heat affects the liver and gallbladder, the main symptoms are jaundice, fever, hypochondriac pain, nausea, and vomiting; when heat is in the nutrient-blood, the main symptoms are high fever, unconsciousness, delirious speech, and macules. Among these, a dry tongue is a sign of pathogenic heat damaging fluids. The focus of treatment is to clear heat, expel pathogens, and preserve fluids, ensuring that once pathogens are eliminated and fluids restored, the dry tongue will naturally resolve. The selection of formulas depends on the location of pathogenic heat. For example, when pathogenic heat congests the lungs, use Ephedra, Apricot Kernel, Gypsum, and Licorice Decoction plus Reed Rhizome, Whole Trichosanthis Fruit, and Heartleaf Houttuynia Herb; for heat in the qi aspect, use White Tiger Decoction Plus Ginseng; for heat accumulation in the stomach and intestines, use Purgative Decoction types; for heat in the liver and gallbladder, use Gentian Liver-Draining Decoction; for heat in the nutrient-blood, use Nutrient-Clearing Decoction or Rhinoceros Horn and Rehmannia Decoction.
2. Yin Deficiency with Fluid Depletion︰Dry tongue, red or deep red texture with little or no coating, mild fever, flushed face, feverish feeling in palms and soles, dry mouth with desire to drink, scanty dark urine, listless spirit, and thready rapid pulse. Caused by Rebing late stage [third stage], prolonged retention of pathogenic heat depleting yin fluids; or chronic sexually transmitted diseases gradually consuming yin due to prolonged illness; or overacting of five minds transforming into fire damaging yin; or indulgence in spicy-hot foods depleting nutritive yin, etc. Yin deficiency with flaming fire damages fluids, resulting in a dry tongue. Key diagnostic points: dry tongue with reduced moisture, red (or deep red) tongue texture with scant coating, accompanied by thirst, restlessness, feverish feeling in palms and soles, flushed face, thready rapid pulse, and other signs of yin deficiency with internal heat. The treatment principle is to enrich yin, clear heat, and promote fluid production. For stomach fluid deficiency, Stomach-Tonifying Decoction is selected; for liver-kidney yin deficiency, Sweet Wormwood and Turtle Shell Decoction. Six-Ingredient Rehmannia Decoction with Ophiopogon Tuber and Schisandra Fruit may also be used.
3. Yang Deficiency with Failure of Fluids to Ascend︰Dry tongue, pale texture, white coating, dry mouth without desire to drink, or preference for hot drinks, complexion pale or bluish-gray and lusterless, fatigue and lethargy, shortness of breath and reluctance to speak, poor appetite, abdominal distension and fullness with cold pain, relieved by warmth, cold limbs, clear urine, loose stools, edema, and deep slow pulse. The syndrome arises from chronic sexually transmitted diseases prolonged without treatment, or due to severe vomiting, diarrhea, or profuse sweating, which depletes yang qi. Weak yang qi leads to dysfunction of the triple energizer's qi transformation, resulting in fluid metabolism disorders and failure of fluids to ascend, causing a dry tongue. *Cold-Damage Disease: On the Original Purpose* states: "Dryness is due to yang qi deficiency, which fails to transform fluids and moisten the upper body." Similarly, *Guide to Tongue Differentiation* notes: "Abdominal distension and fullness, dry mouth, and dry tongue indicate the presence of water qi in the intestines." The clinical features include: dry tongue with white coating and scant fluids, thirst without desire to drink, or preference for hot drinks, accompanied by a pale or dull complexion, fatigue and lethargy, cold limbs, clear urine, loose stools, edema, and other symptoms of yang deficiency. Treatment should focus on warming yang and tonifying qi, and options include Frigid Extremities Decoction with Ginseng; for yang deficiency with water-dampness retention, choose True Warrior Decoction to warm yang and promote water excretion.

Dry tongue is often a sign of fluid injury, either due to pathogenic heat scorching the fluids or yin deficiency leading to fluid depletion. Dry tongue caused by yang deficiency and failure of fluid ascent is due to impaired qi transformation, not fluid injury. The former two are more common, while the latter is relatively rare. The key points for differentiating the three syndromes are:

1. Local changes in the tongue body: In yang exuberance scorching fluids, the tongue is dry, with yellow or scorched and prickly coating, and the tongue texture is slightly red; in yin deficiency with fluid depletion, the tongue is dry, with a deep red texture, and no coating or little coating; in yang deficiency with failure of fluid ascent, the tongue is dry, with a pale texture and a white or dull and dry coating.
2. The degree of thirst: Generally, dry tongue is accompanied by thirst, but the degree of thirst varies among the three. In yang exuberance scorching fluids, there is severe thirst with a preference for cold drinks; in yin deficiency with fluid depletion, thirst is more pronounced with a preference for cool drinks; in yang deficiency with failure of fluid ascent, there is thirst but no desire to drink, or only a small amount, with a preference for warm drinks.
3. Associated symptoms: Yang exuberance scorching fluids is often seen in excess heat pattern, during the intense stage of pathogenic heat; yin deficiency with fluid depletion is often seen in Rebing late stage [third stage], or in the late stage of chronic diseases, manifesting as yin deficiency with internal heat; yang deficiency with failure of fluid ascent is often seen in Zabing late stage [third stage], manifesting as yang deficiency with impaired qi transformation.

Based on the above three aspects, differentiation is not difficult.

bubble_chart Documentation

1. "Guide to Tongue Differentiation: Differentiation of Tongue's Body Fluids": "However, there are also cases where damp evil transmits to the qi aspect, and the qi fails to transform fluids, leading to dryness instead... Dryness of the tongue coating's body fluids indicates that toxic evil has transmitted to the interior... A yellow and dry tongue coating, if accompanied by cold feet and a deep pulse, is not a pure yang syndrome, and one must avoid using purgatives like nitrum and rhubarb."
2. "Selection of Diagnostic Indicators: Inspection": "When the tongue becomes dry, black, and short, it indicates extreme heat in the jueyin or food stagnation in the middle jiao causing distension. Using a large dose of Major Purgative Decoction for purgation can save one or two out of ten. If the stool turns yellow and the fever subsides after taking the decoction, the patient will survive; if the stool remains black and the fever persists, the patient will die."
3. "Essentials of Clinical Practice in Chinese Medicine: Dry Tongue": "A greasy and dry coating indicates consumption of stomach fluids, often seen in the late stage [third stage] of damp-warm disease, with a thick, greasy, and rough coating that feels like sandpaper when touched. Treatment should first focus on generating body fluids, waiting until the fluids are restored and the tongue moistens before addressing the dampness."