The Eight Principles (Ba Gang) Diagnosis is a fundamental method of diagnosis. It utilizes the eight principles of Yin-Yang, Exterior-Interior, Cold-Heat, and Deficiency-Excess to analyze and summarize disease patterns, providing a basis for treatment. The Exterior-Interior principle distinguishes the depth of the disease location; Cold-Heat differentiates the nature of the disease; Deficiency-Excess identifies the strength of the pathogenic factors; and Yin-Yang serves as the overarching principle governing the other six. The Exterior, Heat, and Excess belong to Yang, while the Interior, Cold, and Deficiency belong to Yin. The four pairs of contradictions in the Eight Principles are relative, interconnected, and can transform into one another. The complex clinical symptoms can all be analyzed and summarized using this fundamental method. The Eight Principles Diagnosis is the overarching framework for various diagnostic methods in TCM.
Diagnosis refers to the process of analyzing and identifying the symptoms of a disease, which is the main process and method for understanding and diagnosing diseases. To diagnose means to recognize and differentiate, which involves analysis. Symptoms (Zheng) refer to the comprehensive manifestations of the body’s disordered relationships under the influence of pathogenic factors and conditions, including the interactions between the organs, meridians, Qi, blood, and body fluids. Therefore, clarifying a specific symptom is a summary of the pathological conditions regarding the stage of disease development, including the causes, locations, the strength of the struggle between pathogenic and righteous Qi, and the imbalance of Yin and Yang.
The process of diagnosis is based on theories of the organs, meridians, Qi, blood, body fluids, and pathogenic factors, and involves a comprehensive analysis, summarization, reasoning, judgment, and clarification of the internal relationships among the symptoms and signs collected through the four diagnostic methods: observation, listening, inquiry, and palpation, thereby understanding the disease and making an accurate diagnosis.
Diagnosis and Treatment are two crucial interrelated and inseparable aspects of TCM theory, methods, formulas, and medicines in clinical practice. Diagnosis is the understanding of the disease, while treatment refers to the corresponding therapeutic measures and methods taken based on the diagnosed condition. Diagnosis is the premise and basis for treatment, while treatment is the objective and objective standard for verifying the correctness of the diagnosis.
“Symptoms” refer to individual signs, which are recognized similarly in both Chinese and Western medicine, such as headache, fever, cough, palpitations, nausea, etc.
“Disease” refers to the name of the illness. Among the disease names in TCM, only a few correspond to Western medical terms, such as measles, diphtheria, tetanus, asthma, dysentery, and heat stroke, while most terms differ. Due to the differences in theoretical systems, the understanding of diseases varies between TCM and Western medicine. Western medicine’s understanding of diseases is based on human anatomy and pathophysiology, with clinical diagnosis relying on the patient’s subjective symptoms, physical examination, and laboratory tests. TCM, however, views diseases as results of imbalances in Yin and Yang, with clinical diagnosis primarily based on the patient’s symptoms and signs (such as tongue and pulse diagnosis), without necessarily identifying a disease name but rather clarifying the specific “symptom” (Zheng).
“Symptom” is an abbreviation for evidence and syndrome, which is not merely a symptom or subjective feeling but a group of syndromes. It is TCM’s diagnostic concept of disease. “Symptom” encompasses a set of specific clinical manifestations (symptoms, signs, etc.) and includes a comprehensive concept of the cause, location, nature of the disease, and the comparative strength of the pathogenic and righteous forces. “Symptom” is derived from analyzing symptoms and signs and summarizing them into a concept that better explains the essence of the disease.
TCM diagnosis has been formed through long-term clinical practice, with various methods including Eight Principles Diagnosis, Etiological Diagnosis, Qi-Blood-Body Fluid Diagnosis, Organ Diagnosis, Defensive-Qi-Nutritional Blood Diagnosis, Triple Burner Diagnosis, and Six Meridians Diagnosis. Among these, Eight Principles Diagnosis is the overarching framework for all diagnostic methods.
The Eight Principles Diagnosis is based on the materials obtained from the four diagnostic methods, conducting a comprehensive analysis to explore the nature of the disease, the location of the pathological changes, the severity of the disease, the strength of the body’s response, and the comparative strength of the pathogenic and righteous forces, summarizing them into eight categories of symptoms: Yin, Yang, Exterior, Interior, Cold, Heat, Deficiency, and Excess. This is a fundamental method of TCM diagnosis, encompassing various diagnostic methods and summarizing their commonalities, playing a crucial role in simplifying complex disease processes and capturing the essence of the disease.
Although the manifestations of diseases are extremely complex, they can generally be categorized into the Eight Principles. The overall categories of diseases include Yin and Yang symptoms; the depth of the disease can be classified as Exterior or Interior; the imbalance of Yin and Yang, with Yang excess or Yin deficiency leading to Heat symptoms, and Yang deficiency or Yin excess leading to Cold symptoms; the strength of pathogenic and righteous forces, with strong pathogenic Qi termed Excess symptoms and weak righteous Qi termed Deficiency symptoms. Therefore, the Eight Principles Diagnosis analyzes the ever-changing diseases according to the simple dichotomies of Exterior and Interior, Cold and Heat, Deficiency and Excess, Yin and Yang, revealing the contradictions in the disease process, thus capturing the essence of whether the disease is in the Exterior or Interior, Cold or Heat, Deficient or Excess, Yin or Yang. This is the fundamental spirit of the Eight Principles.
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Eight Principles:(Yin symptoms, Yang symptoms, Exterior symptoms, Interior symptoms, Deficiency symptoms, Excess symptoms, Cold symptoms, Heat symptoms)
1. Exterior and Interior
The Exterior and Interior principles indicate the depth of the disease location and the severity of the condition. Generally speaking, the skin, muscles, and superficial meridians belong to the Exterior; the organs, blood vessels, bone marrow, and internal meridians belong to the Interior. Exterior symptoms indicate that the disease is superficial and mild; Interior symptoms indicate that the disease is deep and severe.
(1) Exterior Symptoms
Exterior symptoms are those that occur superficially in the skin. Generally, they arise when external pathogenic factors invade the body through the skin and nose, leading to a series of symptoms as the righteous Qi (Defensive Qi) resists the pathogenic factors, often seen in the initial stage of external diseases. Exterior symptoms are characterized by sudden onset, short duration, superficial location, and mild severity. They are commonly seen in the early stages of external febrile diseases, such as upper respiratory infections, acute infectious diseases, and other initial stages of infectious diseases.
Main symptoms: fever and chills (or aversion to wind), headache, thin white tongue coating, and floating pulse are the basic symptoms, often accompanied by soreness in the limbs and joints, nasal congestion, cough, and other symptoms.
Due to the differentiation of external pathogenic factors into Cold and Heat, and the varying strengths of the body’s ability to resist these factors, Exterior symptoms can be further divided into Exterior Cold, Exterior Heat, Exterior Deficiency, and Exterior Excess symptoms.
1. Exterior Cold Symptoms
Main symptoms: significant aversion to cold, mild fever, pronounced pain in the head and body, no sweating, clear nasal discharge, and no thirst. The tongue is pale red, with a thin white and moist coating, and the pulse is floating and tight.
Pathogenesis: Cold pathogenic factors are constrained in the skin or muscle layer, leading to a struggle between righteous and pathogenic Qi, hence the aversion to cold and mild fever. The invasion of pathogenic Qi into the superficial meridians causes stagnation in the flow of Defensive Qi and blood, resulting in soreness in the head, body, and limbs. The pulse is floating due to the struggle between righteous and pathogenic Qi at the surface.
Treatment principle: Release the exterior with warm acrid herbs.
Common formula: Ma Huang Tang (Ephedra Decoction).
2. Exterior Heat Symptoms
Main symptoms: significant fever, mild aversion to cold, headache, sore throat, sweating, and thick nasal discharge. The tongue is slightly red, with a thin white coating that is not moist, and the pulse is floating and rapid.
Pathogenesis: The struggle between righteous and pathogenic Qi at the surface leads to fever and mild aversion to cold. Heat pathogenic factors invade the Defensive Qi, causing sweating to escape. Heat damages body fluids, leading to thirst. The presence of heat at the surface results in a floating and rapid pulse.
Treatment principle: Release the exterior with cool acrid herbs.
Common formula: Yin Qiao San (Honeysuckle and Forsythia Powder).
3. Exterior Deficiency Symptoms
Main symptoms: Exterior symptoms with aversion to wind, aversion to cold, and sweating. The tongue is pale, with a thin white coating, and the pulse is floating and weak.
Pathogenesis: The body is constitutionally weak, and the Defensive Yang is not firm, leading to aversion to wind and sweating, with a floating and weak pulse.
Treatment principle: Harmonize the nutritive and defensive Qi, release the exterior and resolve muscle tension.
Common formula: Gui Zhi Tang (Cinnamon Twig Decoction).
4. Exterior Excess Symptoms
Main symptoms: fever, aversion to cold, body aches, and no sweating. The tongue is pale red, with a thin white coating, and the pulse is floating and strong.
Pathogenesis: The pathogenic factors are strong, and the righteous Qi is not weakened; the pathogenic factors are constrained in the skin, and the righteous Qi resists the pathogenic factors, leading to fever and aversion to cold without sweating, with a floating and strong pulse.
Treatment principle: Release the exterior with warm acrid herbs.
Common formula: Ma Huang Tang (Ephedra Decoction).
Distinguishing between Exterior Cold and Exterior Heat symptoms is based on the severity of aversion to cold and fever, as well as tongue and pulse characteristics. Exterior Cold symptoms present with significant aversion to cold and mild fever, while Exterior Heat symptoms present with significant fever and mild aversion to cold. In Exterior Cold symptoms, the tongue coating is thin, white, and moist, with a floating and tight pulse; in Exterior Heat symptoms, the tongue coating is thin, white, and not moist, with a floating and rapid pulse. Additionally, Wind-Cold can transform into Heat, and Exterior Cold symptoms can easily transform into Interior Heat symptoms.
Distinguishing between Exterior Deficiency and Exterior Excess symptoms involves considering the patient’s constitution, with sweating without fluid loss indicating Exterior Excess, commonly seen in younger, robust individuals; while Exterior Deficiency symptoms present with sweating, commonly seen in older, weaker, or chronically ill individuals.
(2) Interior Symptoms
Interior symptoms, in contrast to Exterior symptoms, refer to those that occur deeper within (organs, Qi, blood, bone marrow, etc.).
The causes of Interior symptoms can generally be classified into three situations: first, the progression of Exterior symptoms, where the exterior pathogenic factors have not been resolved and have penetrated into the interior, affecting the organs; second, direct invasion of external pathogenic factors into the internal organs, such as abdominal cold or overconsumption of cold foods leading to Interior Cold symptoms; third, internal injuries from emotional stress, overwork, or dietary factors directly causing dysfunction in the organs, such as dizziness and pain in the liver, palpitations and shortness of breath in the heart, cough and wheezing in the lungs, abdominal distension and diarrhea in the spleen, and low back pain and urinary retention in the kidneys. Therefore, the clinical manifestations of Interior symptoms are complex, and all symptoms that are not Exterior symptoms belong to Interior symptoms. In external diseases, Interior symptoms need to be combined with etiological diagnosis and Defensive Qi-Nutritional Blood diagnosis, while in internal injuries, organ diagnosis is the primary focus. Interior symptoms need to be differentiated into Interior Cold, Interior Heat, Interior Deficiency, and Interior Excess (discussed in the Cold-Heat and Deficiency-Excess sections).
Distinguishing between Exterior and Interior symptoms is primarily based on the inquiry of the patient’s history, the cold-heat nature of the symptoms, and changes in tongue coating and pulse. Generally, new or short-term illnesses are more likely to be Exterior symptoms, while chronic or long-term illnesses are often Interior symptoms. Fever with aversion to cold indicates Exterior symptoms; fever without aversion to cold or only cold without fever indicates Interior symptoms. Exterior symptoms often show no changes in tongue coating or only slight redness at the edges and tip of the tongue; Interior symptoms often present with abnormal tongue coatings, with a floating pulse indicating Exterior symptoms and a deep pulse indicating Interior symptoms.
(3) Half Exterior Half Interior Symptoms
When the pathogenic factors are neither in the Exterior nor have fully entered the Interior, but are in between, the resulting symptoms are termed Half Exterior Half Interior symptoms.
Main symptoms: alternating chills and fever, chest and hypochondriac fullness, bitter taste in the mouth, dry throat, irritability, nausea, loss of appetite, and dizziness. The tongue tip is red, with a mixed yellow and white coating, and the pulse is wiry.
Pathogenesis: The struggle between righteous and pathogenic Qi occurs in the Half Exterior Half Interior region, leading to alternating chills and fever. The pathogenic factors invade this region, affecting the Gallbladder meridian, resulting in chest and hypochondriac fullness, and the heat in the Gallbladder leads to disharmony between the Liver and Stomach, causing irritability, dizziness, nausea, and loss of appetite.
Treatment principle: Harmonize and resolve the Exterior and Interior.
Common formula: Xiao Chai Hu Tang (Minor Bupleurum Decoction).
(4) Simultaneous Exterior and Interior Disease (Mixed Exterior and Interior)
Simultaneous Exterior and Interior disease refers to the occurrence of both Exterior and Interior symptoms at the same time. There are three common situations: first, the initial onset of the disease presents both Exterior and Interior symptoms; second, during the course of the disease, only Exterior symptoms are present initially, but as the pathogenic factors penetrate into the Interior, Interior symptoms appear while Exterior symptoms remain unresolved, also known as simultaneous Exterior and Interior disease; third, if the original disease has not resolved, and new Exterior symptoms arise, such as pre-existing internal injuries combined with external pathogenic factors, or initial external diseases leading to internal injuries, this also constitutes simultaneous Exterior and Interior disease. The treatment principle is to resolve both the Exterior and Interior.
2. Cold and Heat
Cold and Heat are the two principles used to differentiate the nature of diseases, summarizing the two categories of the body’s Yin and Yang balance. Generally, Cold symptoms are manifestations of insufficient Yang Qi or the invasion of Cold pathogenic factors, while Heat symptoms are manifestations of excessive Yang Qi or the invasion of Heat pathogenic factors. The saying goes, “Excess Yang leads to Heat, Excess Yin leads to Cold; Insufficient Yang leads to Cold, Insufficient Yin leads to Heat.” Differentiating Cold and Heat is the basis for using warming or cooling herbs in treatment, hence the saying “Cold is treated with Heat, Heat is treated with Cold.”
(1) Cold Symptoms
Cold symptoms are manifestations of the invasion of Yin Cold pathogenic factors (such as Cold and Dampness) or the deficiency of Yang and excess of Yin, leading to weakened organ function and reduced activity. They can be divided into Exterior Cold symptoms and Interior Cold symptoms; the Exterior Cold symptoms have been discussed in the Exterior section, while here we refer to Interior Cold symptoms.
Main symptoms: aversion to cold, cold limbs, no thirst or preference for warm drinks, pale complexion, cough with white phlegm, abdominal pain relieved by warmth, loose stools, and clear, long urine. The tongue is pale, with a white coating, and the pulse is deep and slow.
Pathogenesis: Yang deficiency and excess Yin lead to coldness in the patient, hence the aversion to cold and cold limbs. The coldness in the spleen and stomach leads to abdominal pain relieved by warmth, and the Yang Qi is weak, resulting in a deep and slow pulse.
Treatment principle: Warm the middle and dispel Cold.
Common formula: Fu Zi Li Zhong Tang (Aconite Decoction to Regulate the Middle).
(2) Heat Symptoms
Heat symptoms are manifestations of the invasion of Yang Heat pathogenic factors (such as Wind, Heat, Fire, etc.) or excessive Yang and insufficient Yin, leading to hyperactivity of organ function and increased activity. They can be divided into Exterior Heat symptoms and Interior Heat symptoms; the Exterior Heat symptoms have been discussed in the Exterior section, while here we refer to Interior Heat symptoms.
Main symptoms: fever, no aversion to cold, irritability, thirst with a preference for cold drinks, red face and eyes, cough with yellow, thick phlegm, abdominal pain relieved by coolness, constipation, and short, red urine. The tongue is red, with a yellow coating, and the pulse is rapid.
Pathogenesis: Excess Yang leads to fever and a preference for coolness, heat damages body fluids, leading to thirst and short, red urine, and constipation. The presence of heat leads to a rapid pulse.
Treatment principle: Clear Heat.
Common formula: Bai Hu Tang (White Tiger Decoction).
(3) Excess Heat and Deficiency Heat
Excess Heat symptoms caused by the invasion of Heat pathogenic factors differ from Deficiency Heat symptoms caused by the deficiency of Yin fluids or hyperactivity of organ function, with different clinical manifestations and treatment principles.
Excess Heat symptoms have a rapid onset and short duration, with high fever, aversion to heat, profuse sweating, delirium, and even mania. Thirst with a preference for drinking, cough with yellow, thick phlegm, purulent phlegm, or blood-streaked phlegm. Constipation, short, red urine, and a red face and eyes. The tongue is red, with a thick yellow coating, and the pulse is rapid and forceful. The heat is intense, often caused by pathogenic Heat (such as infections). Treatment involves clearing Heat and draining Fire.
Deficiency Heat symptoms have a slow onset and long duration, with low fever, tidal fever, night sweats, five-center heat, insomnia, and vivid dreams. Dry mouth with little drinking, scanty, sticky phlegm, or blood-streaked phlegm. Small volume of stool, short, yellow urine. Red cheeks. The tongue is red, with little or no coating, and the pulse is thin and rapid. The deficiency of Yin fluids leads to internal heat. Treatment involves nourishing Yin and clearing Heat.
(4) True Cold and False Heat
In the critical stages of disease development, one can observe some phenomena of “True Cold appearing as Heat” and “True Heat appearing as Cold.” Clinically, the condition that is essentially Heat but presents as Cold is termed “True Heat, False Cold,” while the condition that is essentially Cold but presents as Heat is termed “True Cold, False Heat.” This situation often indicates a more severe disease. If the essence is not grasped, one may be misled by the false appearance, leading to misdiagnosis and mistreatment.
1. “True Cold, False Heat”: For example, patients with chronic wasting diseases often present with fever, flushed cheeks, restlessness, black tongue coating, and a floating pulse. On the surface, it appears to have Heat symptoms, but the patient prefers warmth, is mentally exhausted and apathetic, curled up in bed, with a pale tongue and black, moist coating, and a floating but weak pulse. This indicates that Yin is excessive internally, counteracting Yang externally, and the essence is still Cold, hence termed “True Cold, False Heat.” Treatment should focus on warming the interior and restoring Yang, bringing fire back to the source.
2. “True Heat, False Cold”: This refers to the presence of true Heat internally while appearing as false Cold externally. For instance, in severe heat-related illnesses, one may observe a patient with a dull expression, lethargy, cold hands and feet, and a deep, thin pulse, which superficially resembles Cold symptoms. However, there may also be heat in the mouth and nose, burning sensation in the chest and abdomen, thirst with a preference for cold drinks, constipation, and short, red urine. The tongue is red, with a yellow, dry coating, and the pulse is thin but rapid and forceful. This indicates that internal Yang Heat is constrained and cannot express outwardly, hence termed “True Heat, False Cold.” Treatment should focus on clearing and draining internal Heat and promoting Yang Qi.
In general, the manifestations of Cold and Heat are superficial and represent a false appearance; the internal Cold and Heat represent the essence of the disease.
To differentiate between Cold and Heat symptoms, one should not rely solely on a single symptom or sign but should observe the overall manifestations of the disease, especially the aspects of Cold-Heat, thirst or no thirst, complexion, temperature of the limbs, urination, tongue appearance, and pulse characteristics. For instance, aversion to cold and preference for warmth indicates Cold; fever, aversion to heat, and preference for coolness indicate Heat; a pale tongue with a white coating indicates Cold, while a red tongue with a yellow coating indicates Heat. From the comparison of Cold and Heat symptoms, it can be seen that Cold symptoms belong to excess Yin, often accompanied by Yang deficiency; Heat symptoms belong to excess Yang, often showing signs of Yin fluid deficiency.
3. Deficiency and Excess
Deficiency and Excess are the two principles used to differentiate the strength of the body’s righteous Qi and the severity of pathogenic factors. Generally, Deficiency refers to insufficient righteous Qi, and Deficiency symptoms are manifestations of insufficient righteous Qi, while Excess refers to the overabundance of pathogenic Qi, and Excess symptoms are manifestations of excessive pathogenic Qi. The Suwen states, “When pathogenic Qi is strong, it is Excess; when vital Qi is depleted, it is Deficiency.” From the perspective of the comparative strength of righteous and pathogenic forces, Deficiency symptoms indicate insufficient righteous Qi, while pathogenic Qi is not strong; Excess symptoms indicate excessive pathogenic Qi, but righteous Qi has not yet declined, representing a fierce struggle between righteous and pathogenic forces. Differentiating between Deficiency and Excess is the basis for determining whether to tonify (nourish Deficiency) or drain (eliminate Excess) in treatment, hence the saying “Deficiency is tonified, Excess is drained.”
(1) Deficiency Symptoms
Deficiency symptoms arise from a weak constitution (either congenital or acquired), prolonged illness damaging the righteous Qi, excessive blood loss, loss of essence, profuse sweating, or invasion of external pathogenic factors damaging the righteous Qi.
Main symptoms: pale or sallow complexion, mental fatigue, physical weakness, palpitations, shortness of breath, cold limbs, or five-center heat, spontaneous sweating, night sweats, loose stools, frequent urination, pale tongue with little or no coating, and weak pulse.
Clinically, due to deficiencies in Qi, blood, Yin, or Yang, they can be classified into Qi Deficiency, Blood Deficiency, Yin Deficiency, and Yang Deficiency, with various organ-specific Deficiency symptoms (such as Lung Qi Deficiency, Heart Blood Deficiency, Liver Yin Deficiency, Spleen Qi Deficiency, Kidney Yang Deficiency, etc.). Below are the symptoms and treatment principles for Qi Deficiency, Blood Deficiency, Yin Deficiency, and Yang Deficiency. Organ-specific Deficiency symptoms will be discussed in the organ diagnosis section.
The common symptoms of Qi Deficiency and Yang Deficiency are: pale or sallow complexion, mental fatigue, physical weakness, low voice, spontaneous sweating, reduced appetite, pale, swollen tongue, and weak pulse. The difference is that Qi Deficiency presents with shortness of breath, fatigue, and rapid breathing upon exertion, with a weak pulse. Treatment principle: Tonify Qi, commonly using Si Jun Zi Tang (Four Gentlemen Decoction).
Yang Deficiency presents with aversion to cold, cold limbs, clear, long urination, and diarrhea with clear stools, with a slow pulse. Treatment principle: Tonify Yang, commonly using Shen Qi Wan (Kidney Qi Pill) or Ren Shen Rong Wan (Ginseng and Deer Antler Pill).
Blood Deficiency and Yin Deficiency share common symptoms: emaciation, dizziness, blurred vision, insomnia, palpitations, and thin pulse. The difference is that Blood Deficiency presents with a pale, dull complexion or sallow skin, numbness in the hands and feet, pale lips and nails, pale tongue, and weak pulse. Treatment principle: Nourish Blood, commonly using Si Wu Tang (Four Substance Decoction).
Yin Deficiency presents with low fever or tidal fever, flushed cheeks, five-center heat, dry mouth, dry throat, night sweats, red tongue, thin or cracked tongue, little or no coating, and thin rapid pulse. Treatment principle: Nourish Yin, commonly using Liu Wei Di Huang Wan (Six Flavor Rehmannia Pill).
From the above, it can be seen that Qi Deficiency and Yang Deficiency both belong to insufficient Yang Qi, hence the clinical manifestations are similar, both presenting with pale complexion, fatigue, and spontaneous sweating. However, they also have distinctions: Qi Deficiency is characterized by weakness without “Cold symptoms,” while Yang Deficiency presents with weakness accompanied by “Cold symptoms” — aversion to cold, cold limbs, and slow pulse. Blood Deficiency and Yin Deficiency both belong to insufficient Yin fluids, hence the clinical manifestations are similar, both presenting with emaciation, dizziness, palpitations, and insomnia. However, they also have distinctions: Blood Deficiency is characterized by weakness without “Heat symptoms,” while Yin Deficiency presents with insufficient Yin fluids leading to excessive Yang Qi, hence showing “Heat symptoms” — low fever or tidal fever, dry mouth, and dry throat.
(2) Excess Symptoms
Excess symptoms arise from a robust constitution of the patient, sudden illness due to external pathogenic factors, or dysfunction of the organs leading to the accumulation of certain pathological products, such as Qi stagnation, blood stasis, phlegm-dampness, parasitic accumulation, or food stagnation.
Clinically, the manifestations vary depending on the nature of the pathogenic factors and the organs affected, characterized by excessive pathogenic Qi and weakened righteous Qi, with a fierce struggle between the two. Common symptoms include high fever, flushed face, irritability, delirium, loud voice, abdominal distension and pain with tenderness, excessive phlegm, constipation, and difficulty urinating, or the presence of blood stasis, swelling, edema, food stagnation, or parasitic accumulation, with thick, greasy tongue coating and a strong pulse.
Treatment principle: Drain Excess and attack the pathogenic factors, hence the saying “Excess is drained.” However, different methods of draining, such as clearing Heat, promoting bowel movements, draining water, dispelling phlegm, regulating Qi, invigorating blood, resolving stasis, and eliminating parasites, will be discussed in relevant sections.
Distinguishing between Deficiency and Excess can be considered from the following aspects: regarding the time of onset, new or acute illnesses or short duration are often Excess symptoms, while chronic or long-standing illnesses are often Deficiency symptoms; regarding the etiology, external pathogenic factors often lead to Excess symptoms, while internal injuries often lead to Deficiency symptoms; regarding the constitution, younger and stronger individuals are more likely to present with Excess symptoms, while older and weaker individuals are more likely to present with Deficiency symptoms; regarding clinical symptoms and signs, the following distinctions can be made:
Deficiency symptoms: pale, sallow, or dull complexion, fatigue, low voice, tenderness upon palpation, pale tongue with a white coating or little coating, and weak pulse. Treatment principle: Tonify Deficiency.
Excess symptoms: flushed face, irritability, delirium, loud voice, severe pain with tenderness, red tongue with a thick yellow coating, and strong pulse. Treatment principle: Drain Excess.
4. Yin and Yang
Yin and Yang are the two principles used to differentiate the nature of diseases, serving as the overarching framework for the Eight Principles, summarizing the Exterior-Interior, Cold-Heat, and Deficiency-Excess principles. The “Classifications of Yin and Yang” states, “In human diseases, there must be a basis, either rooted in Yin or in Yang. Although the manifestations of diseases are numerous, they ultimately fall into two categories: Yin and Yang.” This indicates that although symptoms may be complex and varied, they ultimately do not exceed the two categories of Yin and Yang, and thus the key to diagnosing diseases must first clarify whether they belong to Yin or Yang. Generally, Exterior, Excess, and Heat symptoms belong to Yang, while Interior, Deficiency, and Cold symptoms belong to Yin. Clinically, Yin symptoms often refer to Interior Deficiency Cold symptoms, while Yang symptoms often refer to Interior Excess Heat symptoms.
(1) Yin Symptoms
Yin symptoms are characterized by the deficiency of Yang Qi and excess of Yin. Generally, Yin symptoms are always accompanied by Cold manifestations, such as aversion to cold, absence of fever, cold limbs, mental fatigue, and a slow or weak pulse. They arise from the low function of the organs and a weakened response of the body, often seen in older, weaker individuals or those with chronic illnesses, presenting a picture of deficiency and Cold.
(2) Yang Symptoms
Yang symptoms are characterized by the excess of Yang Qi and the absence of deficiency in righteous Qi. Generally, Yang symptoms are always accompanied by Heat manifestations, such as fever, aversion to heat, warm limbs, irritability, thirst, and a rapid pulse. They arise from the hyperfunction of the organs and are often seen in robust individuals, presenting a picture of excess and Heat.
(3) Loss of Yin and Loss of Yang
Loss of Yin and Loss of Yang are two dangerous conditions that can occur during the disease process, often seen in cases of high fever, profuse sweating, severe vomiting and diarrhea, or excessive blood loss, leading to rapid loss of Yin fluids or Yang Qi, commonly seen in patients in shock. Although Loss of Yin and Loss of Yang fall under the category of Deficiency symptoms, they are distinguished from general Deficiency symptoms due to their special and critical nature.
The clinical manifestations of Loss of Yin and Loss of Yang, in addition to various critical symptoms of the primary disease, often present with varying degrees of sweating. However, the sweating in Loss of Yin is hot and sticky, often accompanied by skin heat, warm hands and feet, thirst with a preference for drinking, and a thin, rapid pulse, indicating Yin depletion and Yang excess; while the sweating in Loss of Yang is profuse and cool, often accompanied by aversion to cold, lethargy, cold limbs, and a weak pulse, indicating Yang collapse and excess Yin. Since Yin and Yang are interdependent, depletion of Yin fluids leads to the dispersion of Yang Qi, while depletion of Yang Qi leads to the inability of Yin fluids to generate, thus the clinical manifestations of Loss of Yin and Loss of Yang are difficult to separate, with rapid transformations occurring between them, only differing in their primary and secondary characteristics.
The treatment for both Loss of Yin and Loss of Yang focuses on supporting the righteous Qi and stabilizing the condition. For Loss of Yin, the approach is to tonify Qi, consolidate Yin, and restore fluids, often using Sheng Mai San (Generate the Pulse Powder); for Loss of Yang, the approach is to tonify Qi, stabilize the condition, and restore Yang, often using Du Shen Tang (Ginseng Decoction) or Shen Fu Tang (Ginseng and Aconite Decoction).
The distinctions among the Eight Principles of Exterior-Interior, Cold-Heat, Deficiency-Excess, and Yin-Yang are not simple, isolated, or static, but rather complex, interrelated, and capable of transformation. In summary, the Eight Principles exhibit relationships of “coexistence,” “mixing,” and “transformation.”
(1) Coexistence
“Coexistence” refers to the simultaneous appearance of symptoms from two or more principles, such as in the early stages of external febrile diseases, where both Exterior symptoms and further differentiation into Cold or Heat may be observed, thus classified as Exterior Cold or Exterior Heat symptoms; in chronic diseases, often Deficiency symptoms may also require further differentiation into Deficiency Cold or Deficiency Heat symptoms. The appearance of coexisting symptoms should not be viewed equally, but rather with a primary and secondary relationship, such as Exterior Cold and Exterior Heat symptoms, where Exterior symptoms are primary, and Cold or Heat is secondary, thus treatment should primarily focus on releasing the Exterior, using warm acrid herbs for Cold or cool acrid herbs for Heat; similarly, Deficiency Cold and Deficiency Heat symptoms are primarily Deficiency symptoms, with Cold or Heat being secondary, thus treatment should primarily focus on tonifying Deficiency, using warming methods for Yang or nourishing methods for Yin. In cases of coexisting Exterior and Interior symptoms, the primary focus should be determined based on the specific condition.
(2) Mixing
“Mixing” refers to the simultaneous appearance of opposing symptoms from two principles, such as Cold-Heat mixing, Deficiency-Excess mixing, or Exterior-Interior mixing (commonly referred to as simultaneous Exterior and Interior disease). Additionally, during the progression of a disease, some false appearances may arise, such as True Heat appearing as Cold or True Cold appearing as Heat. Therefore, during the diagnostic process, careful observation and comprehensive analysis are essential to discern the truth and avoid misdiagnosis and mistreatment, which could delay treatment.
(3) Transformation
“Transformation” refers to the transformation of symptoms from one principle to its opposing counterpart. The relationships between Exterior and Interior, Cold and Heat, Deficiency and Excess, and Yin and Yang are both opposing and can transform into one another under certain conditions. For example, Exterior pathogenic factors causing aversion to cold and fever may, due to disease progression or improper treatment, penetrate into the Interior, leading to a transformation from Cold symptoms to Heat symptoms, ultimately resulting in the transformation from Exterior Cold symptoms to Interior Heat symptoms; Excess symptoms may, due to misdiagnosis or improper treatment, lead to prolonged disease progression, where although the pathogenic factors gradually diminish, the righteous Qi is also damaged, gradually transforming into Deficiency symptoms. Conversely, Deficiency symptoms may lead to insufficient righteous Qi, resulting in the generation of phlegm, dampness, Qi stagnation, or blood stasis, leading to various Excess symptoms. Transformation can only occur under certain conditions, and during diagnosis, it is crucial to continuously observe changes in the pathogenesis, timely diagnose and treat, to prevent the disease from worsening and promote recovery.
The application of Eight Principles Diagnosis begins with differentiating between Exterior and Interior to determine the location of the disease; then differentiating Cold and Heat, Deficiency and Excess, to clarify the nature of the disease and understand the comparative strength of the pathogenic and righteous forces; finally, the Yin-Yang principle can be used for a comprehensive summary.
Eight Principles Diagnosis (Mnemonic Verse)
The Eight Principles Diagnosis is the overarching principle, each disease has its cause, the organ diagnosis is the core, Qi, blood, and body fluids are clearly differentiated, external febrile diseases are layered, and the judgment of disease symptoms is key.
Exterior Symptoms
Exterior symptoms arise from the invasion of the skin, with nasal congestion, runny nose, headache, fever, aversion to cold, with or without sweating, cough, thin white tongue coating, and floating pulse.
Interior Symptoms
Interior symptoms arise from the transmission of Exterior symptoms or internal generation, with the disease located deep within the organs, Qi, and blood, all non-Exterior symptoms belong to the Interior.
Cold Symptoms
Cold symptoms arise from the invasion of Cold pathogenic factors, with Yang deficiency and excess Yin leading to aversion to cold, preference for warmth, cold limbs, pale complexion, loose stools, clear urine, pale tongue with white coating, and slow pulse.
Heat Symptoms
Heat symptoms arise from the invasion of Heat pathogenic factors, or from excessive Yang and insufficient Yin, leading to irritability, thirst, preference for cold drinks, fever, preference for coolness, red face, constipation, and rapid pulse.
Deficiency Symptoms
Deficiency symptoms arise from insufficient righteous Qi, with pale complexion, fatigue, low voice, spontaneous sweating, loose stools, frequent urination, pale tongue with little or no coating, and weak pulse.
Excess Symptoms
Excess symptoms arise from excessive pathogenic Qi, with flushed face, irritability, delirium, loud voice, severe pain with tenderness, red tongue with thick yellow coating, and strong pulse.
Yang Symptoms
Yang symptoms are characterized by the desire to see light, with irritability, loud voice, aversion to heat, thirst for cold drinks, constipation, short red urine, red face, red tongue with yellow coating, and rapid pulse, indicating excessive Yang and Heat symptoms.
Yin Symptoms
Yin symptoms are characterized by the desire to avoid light, with mental fatigue, low voice, aversion to cold, cold limbs, spontaneous sweating, clear urine, pale tongue with white coating, and slow pulse, indicating excessive Yin and Cold symptoms.
