Identifying All Yang Deficiency Syndromes
For individuals with Yang deficiency, Yin energy must naturally be abundant (the term Yin energy refers to the abundance of water, which is blood. When blood is abundant, Qi is weak, which is the cause of Yang deficiency). Although all symptoms of fire may appear externally (this fire is called “false fire,” distinct from “true fire.” True fire is caused by external pathogens entering the Yang channels, resulting from stagnation. False fire arises when Yin energy ascends, where Yin refers to water, and Qi refers to the innate Yang of water; hence it is called false fire. Water Qi flows downward as normal, while upward movement is abnormal, resulting from the weakness of the monarch fire, which cannot restrain and absorb, leading to ascension and illness), it is similar to true fire, and all should be distinguished by this method, ensuring no mistakes.
In cases of Yang deficiency, the individual will exhibit a pale blue-white complexion, lack of spirit in the lips and mouth, closed eyes and fatigue, low voice and short breath, little energy and reluctance to speak, heavy body and fear of cold, expectoration of clear water, lack of appetite, tongue that is blue and slippery, or black and moist with a pale blue-white color, or light yellow and moist, with abundant saliva in the mouth, disinterest in drinking water, preferring hot soup, normal urination, pulse that is floating and weak, fine and without strength, spontaneous sweating, cold limbs, blue nails, abdominal pain with a contracted feeling, and various symptoms that are the true manifestations of Yang deficiency. When using medicine, one should support Yang and suppress Yin (supporting Yang includes the upper, middle, and lower aspects, such as Gui Zhi (Cinnamon Twig), Ren Shen (Ginseng), and Huang Qi (Astragalus) for supporting upper Yang; Jiang (Ginger), Cao Guo (Tsaoko Cardamom), and Xi Sha (Sand Ginger) for supporting middle Yang; Tian Xiong (He Shou Wu), Fu Zi (Aconite), and Liu Huang (Sulfur) for supporting lower Yang). However, there are also symptoms resembling true fire that should be noted. Yang deficiency symptoms may include a face that is red like vermilion resembling true fire (indicating that Yuan Yang is externally excessive, which can be confirmed by the above symptoms), a pulse that is extremely large and strong like a stone (indicating that Yuan Yang is violently lost, which can also be confirmed by the above symptoms), and a body that is very hot (this can be due to three reasons: one is that Yuan Yang is externally excessive, and the body must not be painful or thirsty, with no external pathogens to confirm; the second is that postpartum blood is suddenly deficient, and Yang has no attachment; the third is that vomiting blood injures Yin, and Yuan Qi has no support, causing the Qi mechanism to rise externally, and Yuan Qi also rises externally). There may also be bleeding from the gaps between the teeth (indicating that Yang Qi is deficient and cannot control blood, leading to excessive blood flowing outward), and symptoms of shortness of breath, cough with phlegm (the lungs are the organ of clear deficiency, which cannot tolerate even a trace of Yin energy; now the heart and lung Yang is insufficient, hence cannot control the ascending Yin energy. Yin energy refers to kidney water and kidney fire, indicating internal injury), and difficulty in urination (indicating that Yang is insufficient to transform Yin, which can also be confirmed by the above symptoms). This section briefly outlines a few points; further exploration of Yang deficiency through questions and answers will clarify.
【Explanation】 Zheng states at the beginning of this book: “In medicine, it is not difficult to use medicine, but it is difficult to recognize symptoms; it is also not difficult to recognize symptoms, but it is difficult to understand Yin and Yang.” He also says: “Chen Xiuyuan’s medical books, thirteen in total, draw from the ancient and apply to the present, discussing deeply and annotating lightly, gaining much from Zhang Zhongjing’s subtlety, and also being clear. Among them, the division of Yin and Yang is based on practical evidence, and the lively mechanism of using medicine is sometimes briefly mentioned but not detailed.” Therefore, he wrote the two works “Medical Principles True Transmission” and “Medical Methods Round Communication.” In discussing the practical evidence of Yang deficiency and Yin deficiency, and the lively and flexible use of formulas and methods, he elaborates on dozens of points to clarify Zhang Zhongjing’s painstaking efforts in establishing laws and prescribing formulas, which also serves to supplement the shortcomings of Mr. Xiuyuan. Thus, his method of identifying all Yin deficiency and Yang deficiency syndromes is a comprehensive and appropriate accumulation of the achievements of predecessors, combined with his own clinical experience over decades, making it quite comprehensive and practical. The Yang deficiency symptoms mentioned in this section have been verified by the author over many years of clinical practice, and I am confident in their authenticity. For any of these symptoms, using the medicine to support Yang and suppress Yin with modifications and combinations will yield effective results. Any fire symptoms without these symptoms are all true fire. However, there are also Yang deficiency symptoms that resemble true fire, such as the red face like vermilion mentioned by Zheng; although all fire signs may appear externally, they should not be mistaken for true fire and must be carefully distinguished. As long as there are Yang deficiency symptoms to rely on, one should still use medicines that support Yang and suppress Yin for treatment.
Zheng states: Tian Xiong (He Shou Wu), Fu Zi (Aconite), and Liu Huang (Sulfur) support lower Yang, which has its characteristics. Li Shizhen’s “Compendium of Materia Medica” states that Wu (Black), Fu (Aconite), and Tian Xiong (He Shou Wu) are all medicines that supplement the Yang of the lower jiao (the gate of life) due to their similar nature and different names, all possessing pungent, hot properties and being toxic, requiring preparation before use. They are indeed essential medicines for treating lower jiao Yang deficiency. As for Liu Huang, it is also very hot and pure Yang, capable of supplementing the true fire of the gate of life. Long Huitang’s “Foolish Doctor” also states: “Liu Huang is originally the essence of fire, capable of clearing all damp heat.” However, due to its sour and toxic nature, it is generally used sparingly for internal use. Only Zhang Yan is known for its effective use; in his work “Medical Records of Chinese and Western Medicine,” he states: “Over the past ten years, I have cured countless cases of chronic cold diseases using raw Liu Huang. Liu Huang is originally non-toxic; its toxicity is its heat, so taking a small amount will not feel hot, and it does not harm the person at all, so it can be taken without preparation and can even be taken regularly. Moreover, throughout history, discussions on Liu Huang have always claimed its efficacy surpasses that of Gui (Cinnamon) and Fu (Aconite). However, using it raw is a foolish view, and it is based on my gradual experimentation, confirming its remarkable and stable efficacy, thus I dare to use it for treatment. Nowadays, hundreds of people in the city take raw Liu Huang daily, all of whom have increased their appetite and strengthened their bodies, all thanks to my guidance.” I also often use Liu Huang to treat patients; for any symptoms of gate of life fire decline and chronic cold diseases, it is particularly effective, but I do not use it raw; it must be prepared before being used in decoctions or pills. The method is to hollow out a radish, place Liu Huang inside, seal it, and boil it for two hours to remove its odor; or it can be boiled with tofu for two hours as well. A patient, Liu ××, could not eat, and even water was vomited. Upon examination, it was diagnosed as cardia cancer, requiring surgical removal. I diagnosed it as a choking disease with obvious Yang deficiency symptoms and gate of life fire decline, so I used a modified version of Fu Zi Li Zhong Decoction, adding 20 to 30 grams of Liu Huang, and after three months of medication, he was completely cured, and it has been five years without recurrence, which proves the efficacy of Liu Huang and its potential for broader application.
As for the bleeding from the gaps between the teeth mentioned by Zheng, it is due to Yang deficiency’s inability to control blood, leading to excessive blood flowing outward, which is also a confirmed observation. I often use the principle that “teeth belong to the kidneys” and apply Si Ni Decoction with Gui (Cinnamon) to treat such symptoms, achieving significant results.
For those with shortness of breath and cough with phlegm, Zheng indicates that this is due to insufficient heart and lung Yang, hence unable to control the ascending kidney water and kidney fire, which is indeed a statement based on experience. For treating such symptoms, as long as the expectorated phlegm is white and foamy or salivary, slightly salty, with shortness of breath and chills, I use Fu Zi Li Zhong Decoction with Sha Ren (Cardamom), and it always yields effective results.
Regarding constipation, resembling sheep droppings, it is generally thought to be due to excessive fire. Zheng points out that it is due to Yang not transforming Yin, which is also Yin binding. I follow his idea and use Fu Zi Li Zhong Decoction combined with Ban Xia (Pinellia) pills, adding Rou Cong Rong (Cistanche), Ma Ren (Hemp Seed), and Xing Ren (Apricot Kernel) for effectiveness. Liu Huang’s nature is very hot and can supplement the true fire of the gate of life, promoting Yang Qi to unblock the large intestine, and is also assisted by Ban Xia’s ability to descend turbidity. Therefore, Ban Xia pills have long been a good agent for treating Yin binding.
Identifying All Yin Deficiency Syndromes
For individuals with Yin deficiency, Yang energy must naturally be abundant (the term Yang energy refers to the abundance of fire. When fire is abundant, water is depleted, which is the cause of Yin deficiency). Although all symptoms of Yin may appear externally, resembling Yang deficiency symptoms, they should be distinguished by this method, ensuring no mistakes. In cases of Yin deficiency, the individual will exhibit a red complexion, energetic spirit, wide-open eyes and insomnia, loud voice, foul breath, light body and aversion to heat, difficulty in urination, thirst for cold drinks, tongue coating that is dry yellow or black-yellow, with no saliva, prickly sensation in the mouth, irritability and harsh speech, or tidal fever and night sweats, dry cough without phlegm, continuous drinking of water, six pulses long and strong, and various symptoms that are the true manifestations of Yin deficiency. When using medicine, one should nourish Yin to break Yang (nourishing Yin includes all six Yin aspects, referring to the discussion on the rise and fall of Qi and blood, where excess Qi indicates a segment of fire; the methods of preserving Yin, saving Yin, transforming Yin, and nurturing Yin are all available, and careful consideration will reveal the path of Yin deficiency). However, there are also symptoms resembling Yang deficiency, with several indicators. Yin deficiency symptoms may include a pulse that is hidden and not visible, or fine like a thread, while if Yang deficiency is extreme (extreme heat leads to a hidden pulse, which can be confirmed by the above symptoms), there may be cold limbs like ice, while if Yang is completely exhausted (pathogenic heat is hidden internally, and Yang Qi does not reach the four extremities, which can also be confirmed by the above symptoms), there may be sudden vomiting and diarrhea, profuse sweating like Yang collapse (this heat is hidden internally, forcing out vomiting and diarrhea, which can also be confirmed by the above symptoms), and a desire to speak but unable to (heat phlegm rises and obstructs, which can also be confirmed by the above symptoms). This section merely outlines a few points; further exploration of Yin deficiency through questions and answers will clarify.
It is noted that Yin deficiency symptoms are all due to abundant fire (fire is Qi), and excessive fire injures blood, which is an unchanging principle throughout the ages. Later scholars specifically discuss fire, while the true nature of Yin deficiency symptoms is completely obscured. Zhang Zhongjing’s methods of preserving Yin, transforming Yin, nurturing Yin, and saving Yin have all been abandoned, and no one recognizes them; thus, I particularly provide evidence for this.
【Explanation】Individuals with Yin deficiency, due to excess Qi, have abundant fire, hence often experience water depletion and blood deficiency. The symptoms they exhibit are often opposite to those of Yang deficiency. Individuals with Yang deficiency, due to insufficient Qi, cannot control blood, leading to blood flow stagnation and slow movement, with body temperature often being low. Individuals with Yin deficiency, with water depletion and fire abundance, hence body temperature is often high and various fever phenomena are present. In clinical practice, whenever Yin deficiency symptoms are observed, the medicine should be used to nourish Yin and suppress Yang. Although all Yin signs may appear externally, resembling Yang deficiency, as Zheng mentioned in several situations, as long as there are various symptoms of Yin deficiency, treatment should still be based on Yin deficiency.
Appendix: Eighteen Points of Yin-Yang Differentiation
(1) Yin Syndrome
All syndromes that conform to the general attributes of “Yin” are called Yin syndromes. For example, internal syndromes, cold syndromes, and deficiency syndromes generally fall within the scope of Yin syndromes.
【Clinical Manifestations】 Generally, internal deficiency cold syndromes all belong to Yin syndromes. Patients may face the wall quietly, close their eyes and dislike brightness (i.e., prefer darkness and love sleep, do not wish to see people), curl up, feel heavy, have a pale or dull complexion or cyanosis, fatigue and weakness, shallow breathing, quiet and few words, low and timid voice, lethargy, mental confusion or coma, grasping at empty lines, feeling for clothes and beds, or preferring warmth, with a bland mouth and no thirst, cold body, cold hands and feet, dry skin, clear and long urination, loose stools, pulse that is deep and slow or weak or thin and rough, tongue that is pale, plump, and tender, with a white and slippery coating. Additionally, any disease in the blood or organs also falls within the scope of Yin syndromes.
【Syndrome Analysis】 Mental fatigue, weakness, and low voice are manifestations of deficiency syndromes. Cold limbs, clear and long urination, and loose stools are manifestations of internal cold. A pale, plump, and tender tongue, deep and slow pulse, weak, thin, and rough pulse are all signs of deficiency cold.
（2）Yang Syndrome
All syndromes that conform to the general attributes of “Yang” are called Yang syndromes. For example, exterior syndromes, heat syndromes, and excess syndromes generally fall within the scope of Yang syndromes.
【Clinical Manifestations】 Generally, exterior heat excess syndromes all belong to Yang syndromes. Yang syndrome patients may lie facing outward, open their eyes and enjoy seeing people (with some exceptions for those who are shy of light), stretch their bodies, feel light, have a red complexion, flushed face, bright eyes, aversion to cold and fever, skin burning hot, dry mouth and throat, thirst for cold drinks, restlessness and insomnia, mental agitation, loud and coarse voice or shouting, deep and long breathing, shortness of breath with phlegm, clear and loud voice, warm body and warm hands and feet, moist skin, constipation, foul-smelling stools, painful and burning urination, pulse that is floating, rapid, or strong and forceful, tongue that is red and dry, with a thick yellow or black coating, or prickly sensation. Additionally, any disease in the Qi or Wei levels or in the bowels also falls within the scope of Yang syndromes.
【Syndrome Analysis】 Yang syndrome is a summary of exterior syndromes, heat syndromes, and excess syndromes. The simultaneous presence of aversion to cold and fever is characteristic of exterior syndromes. A red complexion, mental agitation, burning skin, dry mouth, and thirst for cold drinks are manifestations of heat syndromes. A coarse voice, deep breathing, shortness of breath with phlegm, and constipation are also manifestations of excess syndromes. A red tongue, thick yellow or black coating, and a floating, rapid, strong, or forceful pulse are all signs of excess heat.
（3）Differentiation of Yin and Yang Syndromes
Yin and Yang growth and decline are relative; when Yang is strong, Yin declines, and when Yin is strong, Yang declines. For example, if the pulse is found to be large and strong, the tongue is red and the coating is dry, accompanied by thirst, strong heat, etc., it can be concluded that Yang is strong and Yin is weak. If the pulse is found to be deep and slow, the tongue is white and the coating is moist, accompanied by abdominal pain and diarrhea, it can be concluded that Yin is strong and Yang is weak. Additionally, the complex changes of Yin and Yang are specifically manifested in the six categories of exterior and interior, cold and heat, deficiency and excess. Yin deficiency syndrome is also called deficiency heat syndrome, while Yang deficiency syndrome is also called deficiency cold syndrome. The kidneys are the root of Yin and Yang in the human body; when Yin and Yang have been deficient for a long time, or due to prolonged illness, it will damage kidney Yin and Yang, leading to true Yin deficiency or true Yang deficiency, which is the deficiency of true Yin and true Yang.
“Gu Songyuan’s Medical Mirror” discusses the differentiation of Yin and Yang diseases, mentioning the division of day and night severity, which can also serve as a reference. It states: “Yang diseases are heavier during the day and lighter at night, as Yang Qi and pathogenic Qi are both strong; Yin diseases are lighter during the day and heavier at night, as Yin Qi and pathogenic Qi are both strong. If it is Yang deficiency disease, it is lighter during the day; if it is Yin deficiency disease, it is lighter at night. Yin and Yang each return to their respective divisions; this also refers to their changes, and should not be rigid. This emphasizes that the practitioner should determine the timing to confirm the disease; if it has not yet developed, it should be welcomed and guarded (treating Yin and Yang according to the situation); if it is in the acute phase, it should be avoided; if it has already developed, it should be countered; whether during the day or night, it may occur intermittently. If it occurs out of time, it is purely a deficiency syndrome, and should not be restricted to day and night; one should take nourishing medicines broadly to support the righteous Qi.
（4）True Yin Deficiency (Kidney Yin Deficiency)
True Yin deficiency is caused by the deficiency of true Yin in the kidneys, such as the common clinical manifestations of deficiency heat caused by pulmonary tuberculosis or other chronic consumptive diseases.
【Clinical Manifestations】 Deficiency heat may manifest as a pale face with red cheeks, lips like painted red, five hearts feeling hot, dizziness, tinnitus, dry mouth and throat, hot palms and feet, dizziness and blurred vision, tinnitus, weak lower back and knees, bone steaming and night sweats, nightmares and nocturnal emissions, constipation, short and scanty urination, and a pulse that is thin and rapid, with a red tongue that is dry and has little coating.
【Syndrome Analysis】 With prolonged illness, Yin essence is damaged, affecting true Yin, leading to Yang not being restrained, resulting in deficiency heat, hence the appearance of symptoms such as pale face with red cheeks, red lips, dry mouth, five hearts feeling hot, night sweats, constipation, scanty urination, red tongue that is dry and has little coating, and a thin and rapid pulse. At the same time, since the disease has already harmed kidney Yin, symptoms of kidney dysfunction may also appear. For example, the kidney generates marrow and governs bones, leading to symptoms such as dizziness, blurred vision, weak lower back and knees, and bone steaming; the kidney governs reproduction, and deficiency heat internally disturbs the essence, leading to nightmares and nocturnal emissions.
（5）True Yang Deficiency (Kidney Yang Deficiency)
True Yang deficiency refers to the deficiency of true Yang in the kidneys, where Yang does not support Yin, often seen in various diseases with declining bodily functions and reduced basal metabolism, as well as in elderly and weak individuals.
【Clinical Manifestations】 Pale complexion, cold limbs, fatigue and desire to lie down, cough and shortness of breath, swelling of the body, pale lips and tongue, bland mouth with much saliva, shortness of breath with cough and swelling, spontaneous sweating, dizziness, lack of appetite, abdominal distension and swelling of the shins, loose stools or morning diarrhea, undigested food, impotence, nocturnal emissions, premature ejaculation, cold essence leading to infertility, or cold womb leading to infertility, with a pale, slippery or plump tongue, white slippery coating, and a pulse that is deep and slow or weak at the right wrist.
【Syndrome Analysis】 With prolonged illness, Yang Qi is damaged, affecting true Yang, leading to Yin not being restrained, resulting in internal cold, hence the appearance of symptoms such as pale complexion, cold limbs, pale lips and tongue, bland mouth with much saliva, spontaneous sweating, lack of appetite, pale plump tongue, white slippery coating, and deep, slow, weak pulse. At the same time, since the disease has already harmed kidney Yang, symptoms of kidney dysfunction may also appear. For example, the kidney governs the intake of Qi and water, leading to symptoms such as cough and swelling of the body, abdominal distension and swelling of the shins. The kidney governs reproductive functions, leading to symptoms such as impotence, premature ejaculation, and infertility due to cold essence; kidney deficiency heat leads to symptoms such as morning diarrhea.
（6）Loss of Yin
Loss of Yin refers to the significant loss of body fluids, resulting in the symptoms of Yin fluid depletion. Loss of Yin is a type of deficiency heat syndrome.
【Clinical Manifestations】 Sweating that is sticky, shortness of breath, aversion to heat, warm hands and feet, restlessness or mental confusion, thirst and dry throat, dry lips and tongue, wrinkled skin, sunken eye sockets, cracked lips and tongue, scanty or absent urination, thirst for cold drinks, red and dry tongue, and a pulse that is thin and rapid.
【Syndrome Analysis】 Yin fluids are exhausted, losing their moistening function, hence symptoms such as thirst and dry throat, dry lips and tongue, and wrinkled skin. The depletion of fluids leads to extremely scanty urination. Yin deficiency leads to internal heat, hence warm body and warm limbs. If deficiency heat rises, it leads to restlessness. A red and dry tongue, and a thin and rapid pulse are signs of dry heat due to fluid depletion. Profuse sweating often occurs in patients with original heat diseases, where heat pathogens force fluids to leak out. It can also occur in patients who have been treated improperly, leading to excessive sweating. At this time, profuse sweating is both a cause and a symptom of loss of Yin.
（7）Loss of Yang
Loss of Yang refers to a type of deficiency cold syndrome where Yang deficiency leads to a decline in bodily functions.
【Clinical Manifestations】 Profuse sweating, pale complexion, mental fatigue, cold limbs, aversion to cold and curled up, thirst for hot drinks, bland taste, weak breath, pale and moist tongue, and a pulse that is weak or floating and empty.
【Syndrome Analysis】 Loss of Yang occurs in various conditions leading to Yang Qi weakness, resulting in loss of function. Yang deficiency cannot restrain, hence the pores open and sweat profusely, with cold sweat, bland taste, and slightly sticky texture, which are essential symptoms of loss of Yang. Yang deficiency leads to cold, hence cold body, aversion to cold, and cold limbs.
（8）Differentiation of Loss of Yin and Loss of Yang Syndromes
Loss of Yin and Loss of Yang are dangerous syndromes of disease; a slight error in differentiation or a delay in treatment can lead to immediate death.
Loss of Yin and Loss of Yang refer to the rapid loss of the material basis of life activities and the decline of activity capacity.
Both Loss of Yin and Loss of Yang are caused by high fever, profuse sweating, severe vomiting and diarrhea, excessive blood loss, severe dehydration, collapse, shock, or treatment errors.
Loss of Yin and Loss of Yang are two different types of syndromes; the fundamental cause of Loss of Yin is the significant loss of body fluids, leading to Loss of Yin.The main cause of Loss of Yang is the loss of Yang Qi.Since Qi can be lost with fluids and blood, Loss of Yang is also often seen after excessive sweating, vomiting, diarrhea, or severe bleeding, and many diseases in critical stages can also present with Loss of Yang.
Yin and Yang are opposites that mutually depend on each other; when Yin is depleted, Yang Qi will have no support and will disperse; when Yang is lost, Yin fluids will have no means of transformation and will be exhausted. Therefore, Loss of Yin can quickly lead to Loss of Yang, and Loss of Yang often follows Loss of Yin. The two are only different in priority and sequence, with no clear boundary. In clinical practice, it is important to differentiate the priority of Loss of Yin and Loss of Yang and provide timely treatment.
（9）Excess Yang
Excess Yang refers to a pathological state of functional disorder where the righteous Qi is strong, and the pathogenic Qi is excessive. Excess Yang indicates a pathological state where the righteous Qi has not declined, Yang Qi is relatively excessive, and the functions are hyperactive, leading to excessive heat. The formation of Excess Yang is often due to the invasion of heat pathogens or other pathogens, resulting from Yang transforming into heat; it can also develop from pathological hyperactivity of the body’s functions. Additionally, long-term indulgence in spicy, fatty foods or excessive or improper use of warming and Yang-replenishing substances can also lead to this condition. The main manifestations include strong heat, restlessness, loud voice, red face, thirst, dry stools, scanty and painful urination, rapid and strong pulse, red tongue, and thick yellow coating, all of which are signs of excess heat.
（10）Excess Yin
Excess Yin, commonly referred to as Yin predominance or Yin excess, refers to a pathological state where the righteous Qi has not declined, and Yin Qi is relatively excessive, characterized by functional disorders or imbalances, and insufficient heat. The formation of Excess Yin is often due to the invasion of cold pathogens, indulgence in raw and cold foods, or dysfunction and imbalance of the internal organs, leading to excessive Yin Qi and suppression of Yang Qi. The main manifestations include cold limbs, aversion to cold, abdominal pain, diarrhea, edema, curled up and little movement, bland mouth and no thirst, clear and thin phlegm, pale tongue with white coating, and slow pulse.
（11）Yang Deficiency
Yang deficiency refers to the deficiency of Yang Qi in the body, leading to reduced functions and insufficient heat, manifesting as a pathological state of deficiency cold. “Yang deficiency leads to external cold” refers to this condition. The formation of Yang deficiency is often due to insufficient congenital endowment, lack of nourishment in later life, overwork and exhaustion, or excessive or improper use of cold-clearing and fire-reducing formulas. Clinical manifestations include a pale complexion, cold hands and feet, easy sweating, loose stools, clear urination, pale lips, bland mouth, pale tongue, white and moist coating, and weak pulse. Additionally, traditional Chinese medicine mentions “Yin collapse.” Collapse refers to cold limbs that are not warm. Internal organs are deficient and cold, and Yang Qi cannot reach the four extremities, resulting in coldness, which is called Yin collapse. Yin collapse actually refers to severe Yang deficiency, where the hands and feet are especially cold.
（12）Yin Deficiency
Yin deficiency refers to the depletion of Yin fluids and their functional decline, leading to an inability of Yin to restrain Yang, resulting in a pathological state of deficiency heat, i.e., “Yin deficiency leads to internal heat.” The formation of Yin deficiency is often due to heat pathogens injuring Yin, excessive emotional stress leading to heat damaging Yin, prolonged illness depleting Yin fluids, and insufficient nourishment over time. Clinical manifestations include “five hearts feeling hot,” afternoon tidal fever, night sweats, red lips and dry mouth, tender red or crimson tongue, dry without coating, constipation, and scanty yellow urination, with a thin and rapid pulse.
（13）Yang Excess with Yin Deficiency
In clinical practice, Yang excess, Yin excess, Yang deficiency, and Yin deficiency often do not exist in isolation. Because Yin and Yang exist in a relationship of opposition, mutual dependence, mutual growth and decline, and mutual transformation, when one side of Yin or Yang is excessively strong, it will inevitably affect the other side to varying degrees, leading to damage. For example, Excess Yang can harm Yin, and Excess Yin can harm Yang. The “Suwen: Discussion on Yin and Yang Correspondences” states, “When Yin is strong, Yang is ill; when Yang is strong, Yin is ill,” referring to this situation. In a state of Excess Yang, the intense Yang Qi will inevitably cause varying degrees of damage to Yin fluids. When the damage is slight and the symptoms are not obvious, the essence of the disease remains as Excess Yang; when the damage is severe and the symptoms are obvious, presenting with dry mouth, irritability, scanty and dark urination, dry stools, dry skin, and decreased elasticity, it then transforms into a state of Excess Yang with Yin deficiency, where the essence of the disease is Excess with a mix of deficiency.
（14）Yin Deficiency with Yang Excess
Yin deficiency with Yang excess, commonly referred to as Yang excess, is synonymous with Excess Yang. To standardize the diagnostic terminology, we will refer to Yang excess as Excess Yang. Yin deficiency with Excess Yang and Excess Yang with Yin deficiency are two syndromes that are clinically similar in presentation but differ in pathogenesis. Excess Yang with Yin deficiency occurs first with Excess Yang, which then leads to Yin deficiency due to the consumption of Yin fluids; Yin deficiency with Excess Yang occurs first with the deficiency of essence or fluids, leading to the loss of Yin’s restraint on Yang, resulting in pathological changes of excess. Yin deficiency can lead to Excess Yang, while Excess Yang can consume Yin fluids, exacerbating Yin deficiency; the two are mutually causal. Clinical manifestations include tidal fever, night sweats, five hearts feeling hot, coughing blood, weight loss, insomnia, irritability, or nocturnal emissions, increased sexual desire, red and dry tongue, and thin and rapid pulse. There is also Yin deficiency with Yang floating, indicating true Yin deficiency, with the loss of fluids and blood leading to the floating of Yang Qi. The main manifestations include dizziness, flushed face, red eyes, dry throat, sore throat, and toothache. Yin deficiency with Yang floating is similar to Yin deficiency with Excess Yang, but the symptoms are concentrated in the upper jiao.
（15）Yin Excess with Yang Deficiency
When Yin fluids are excessively abundant, they will inevitably cause varying degrees of damage to Yang Qi. When the damage is slight and the symptoms are not obvious, the essence of the disease remains as Yin excess with cold; when the damage is severe and the symptoms are obvious, presenting with aversion to cold, pale complexion, clear and long urination, and loose stools, it indicates Yang deficiency, resulting from the cold nature of Yin excess, which is accompanied by Yang damage, leading to a state of Yin excess with Yang deficiency, where the essence of the disease is primarily cold with a mix of Yang deficiency.
（16）Yang Deficiency with Yin Excess
Although Yang deficiency with Yin excess and Yin excess with Yang deficiency have similar clinical presentations, their pathogenesis is different. The former is caused by Yang deficiency leading to Yin excess, while the latter is caused by Yin excess leading to Yang deficiency. Yang deficiency with Yin excess refers to kidney Yang deficiency, while Yin excess refers to excessive internal cold. Since kidney Yang deficiency cannot warm and nourish the organs, it leads to decreased organ function, resulting in symptoms of internal cold, such as aversion to cold, cold limbs, diarrhea, edema, and a deep and weak pulse.
（17）Both Yin and Yang Deficiency
Both Yin and Yang deficiency are the result of mutual damage. When either Yin fluids or Yang Qi are deficient to a certain extent, it will affect the other, leading to the pathological changes of both Yin and Yang deficiency. Mutual damage occurs on the basis of either Yin deficiency or Yang deficiency, further developing into this condition. Since the kidneys are the “home of water and fire,” housing the original Yin and Yang, which are the foundation of all organs’ Yin and Yang, any deficiency of Yin or Yang in any organ will inevitably affect kidney Yin or Yang; when kidney Yin or Yang is deficient to a certain extent, it will also affect the other, resulting in both Yin and Yang deficiency. Clinically, there are two situations of both Yin and Yang deficiency:
First, the primary deficiency is Yang deficiency. This is due to more severe Yang Qi deficiency, affecting Yin fluids, leading to insufficiency. The main characteristics are the simultaneous presence of deficiency cold and deficiency heat, with deficiency cold being predominant and deficiency heat being secondary.
Second, the primary deficiency is Yin deficiency. This is due to more severe Yin fluid deficiency, affecting Yang Qi, leading to insufficiency. The characteristics are the simultaneous presence of deficiency cold and deficiency heat, with deficiency heat being predominant and deficiency cold being secondary.
（18）Separation of Yin and Yang
Separation of Yin and Yang, also known as Yin depletion and Yang collapse, refers to a severe stage of disease where Yin and Yang can no longer support each other, leading to disintegration. When clinical symptoms of severe blood loss, severe vomiting and diarrhea, high fever, and other severe loss of Yin symptoms appear, Yin fluids have already been depleted, and Yang Qi may collapse at any time; internal injuries from miscellaneous diseases, such as heart Yin deficiency, can also lead to Yang Qi violently collapsing. Separation of Yin and Yang is the most severe imbalance of Yin and Yang and the final stage, which is a critical mechanism of life-threatening conditions and death. Additionally, it should be noted that in traditional Chinese medicine theory, the frequently discussed Yin syndrome and Yang syndrome. In the previous section, we have commented on this: it is impossible to use Yin and Yang syndromes to encompass all diseases; the specific meanings of Yin syndrome and Yang syndrome refer to deficiency cold syndrome and excess heat syndrome, respectively. In conjunction with the differentiation of Yin and Yang in terms of disease location, to be precise, Yin syndrome should refer to Yang deficiency with cold, while Yang syndrome should refer to excess Yang with heat.
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