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The Eight Principles of Diagnosis in TCM is the overarching framework for various diagnostic methods in Traditional Chinese Medicine.
Diagnosis, refers to the analysis and identification of disease symptoms, which is the primary process and method for understanding and diagnosing diseases.
To distinguish, means to identify and analyze.
Symptoms, refer to the manifestations of the body under the influence of pathogenic factors and conditions, reflecting the disordered relationships between the internal organs, meridians, qi, blood, and body fluids. Therefore, clarifying a specific symptom is a summary of the pathological conditions such as the stage of disease development, the causes, the location of the disease, 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 internal organs, meridians, qi, blood, body fluids, and pathogenic factors, integrating and analyzing the symptoms and signs collected through the four diagnostic methods: observation, listening, inquiry, and palpation, to understand the disease and make an accurate diagnosis.
Diagnosis and treatment are two crucial interrelated aspects of TCM theory, methods, formulas, and medicines in clinical practice. Diagnosis is the understanding of the disease, while treatment is the application of corresponding therapeutic measures and methods based on the diagnosis. Diagnosis is the premise and basis for treatment, while treatment is the objective of diagnosis and an objective standard for verifying the correctness of the diagnosis.
“Symptoms” refer to individual signs, which are recognized similarly in both TCM and Western medicine, such as headache, fever, cough, palpitations, nausea, etc.
“Disease” refers to the name of the illness. In TCM, only a few disease names correspond with those in Western medicine, 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. Western medicine’s understanding is based on human anatomy and pathophysiology, with clinical diagnosis relying on the patient’s subjective symptoms, physical examination, and laboratory tests; TCM 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 clarifying the “symptom.”
“Symptoms” is a shorthand for evidence and syndromes, which is not merely a collection of symptoms or subjective feelings, but a group of syndromes, and also represents TCM’s diagnosis of diseases. “Symptoms” are a set of specific clinical manifestations (symptoms, signs, etc.) that encompass the causes, locations of lesions, nature of the lesions, and the comparative strength of pathogenic and righteous forces. “Symptoms” are derived from analyzing symptoms and signs, summarized into a concept that better explains the essence of the disease.
TCM diagnosis has developed through long clinical practice, employing various methods, primarily including the Eight Principles, etiology diagnosis, qi and blood diagnosis, internal organ diagnosis, defensive qi, nutritive qi, and blood diagnosis, three burner diagnosis, and six meridian diagnosis. Among these, the Eight Principles is the overarching framework for all diagnostic methods.
The Eight Principles of 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 lesions, the severity of the disease, the strength of the body’s response, and the comparative strength of pathogenic and righteous forces, categorizing them into eight types of syndromes: yin, yang, exterior, interior, cold, heat, deficiency, and excess. This is the fundamental method of TCM diagnosis, encompassing the commonalities derived from various diagnostic methods, playing a role in simplifying complexity and summarizing key points in the diagnostic process.
Although the manifestations of diseases are extremely complex, they can generally be categorized into the Eight Principles. The overall categories of diseases include yin syndromes and yang syndromes; the depth of the disease can be divided into exterior and interior; the imbalance of yin and yang, with yang excess or yin deficiency leading to heat syndromes, and yang deficiency or yin excess leading to cold syndromes; the strength of pathogenic and righteous forces, with strong pathogenic qi termed excess syndrome and weak righteous qi termed deficiency syndrome. Therefore, the Eight Principles of 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 within the disease changes, thus capturing the essence of whether the disease is exterior or interior, cold or heat, deficiency or excess, yin or yang. This embodies the fundamental spirit of the Eight Principles.
1
Exterior and Interior
Exterior and interior indicate the depth of the disease and the severity of the condition. Generally speaking, the skin, hair, and superficial muscles belong to the exterior; the internal organs, blood vessels, bone marrow, and internal meridians belong to the interior. Exterior syndrome indicates a superficial disease with mild symptoms; interior syndrome indicates a deeper disease with severe symptoms.(1) Exterior SyndromeExterior syndrome refers to symptoms located superficially in the skin. Generally, it occurs when external pathogenic factors invade the body through the skin and nose, leading to a series of symptoms where the righteous qi (defensive qi) resists the pathogenic factors, often seen in the initial stage of external diseases. Exterior syndrome is characterized by sudden onset, short duration, superficial location, and mild symptoms. It is commonly seen in the early stages of external heat diseases, such as upper respiratory infections, acute infectious diseases, and other initial stages of infectious diseases.Main Symptoms: include fever and chills (or aversion to wind), headache, thin white tongue coating, and floating pulse as the basic symptoms, often accompanied by symptoms such as muscle aches in the limbs and body, nasal congestion, and cough. Due to the cold and heat nature of external pathogens, and the varying strength of the body’s ability to resist them, exterior syndrome can be further divided into exterior cold, exterior heat, exterior deficiency, and exterior excess syndromes. 1. Exterior Cold SyndromeMain Symptoms: severe aversion to cold, mild fever, significant 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 pathogens are constrained in the skin or muscle layers, and the struggle between righteous and pathogenic qi leads to aversion to cold and fever; the invasion of pathogenic qi into the superficial meridians causes stagnation of the defensive qi and blood, resulting in pain in the head and body. 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 Formulas:Ma Huang Tang (Ephedra Decoction)2. Exterior Heat SyndromeMain Symptoms: high fever, mild aversion to cold, headache, sore throat, sweating, and thick yellow nasal discharge, with a preference for cold drinks. 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 pathogens invade the defensive qi, causing sweating. Heat damages body fluids, leading to thirst. The heat pathogen at the surface results in a floating and rapid pulse. Treatment Principle: Release the exterior with cool acrid herbs. Common Formulas:Yin Qiao San (Honeysuckle and Forsythia Powder)3. Exterior Deficiency SyndromeMain 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 patient has a weak constitution, 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, and release the exterior. Common Formulas:Gui Zhi Tang (Cinnamon Twig Decoction)4. Exterior Excess SyndromeMain 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 qi is strong, and the righteous qi is not weakened; the pathogenic qi constrains the skin, and the righteous qi resists the pathogenic qi, 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 Formulas:Ma Huang Tang (Ephedra Decoction)Distinguishing between exterior cold and exterior heat syndromes is based on the severity of aversion to cold and fever, as well as tongue and pulse characteristics. Exterior cold syndrome presents with severe aversion to cold and mild fever, while exterior heat syndrome presents with high fever and mild aversion to cold. In exterior cold syndrome, the tongue coating is thin, white, and moist, and the pulse is floating and tight; in exterior heat syndrome, the tongue coating is thin, white, and not moist, and the pulse is floating and rapid. Additionally, wind-cold pathogens can become stagnant and transform into heat, leading to a transition from exterior cold syndrome to exterior heat syndrome. After the external pathogen invades the skin, it can easily enter the interior and transform into heat, thus exterior cold syndrome (or exterior heat syndrome) can transition into interior heat syndrome.Distinguishing between exterior deficiency and exterior excess syndromes involves considering the patient’s constitution, with the presence of sweating indicating deficiency. Exterior excess syndrome presents with exterior symptoms and no sweating, commonly seen in younger, robust individuals; exterior deficiency syndrome presents with exterior symptoms and sweating, commonly seen in older, weaker individuals or those with chronic illnesses. (2) Interior SyndromeInterior syndrome, in contrast to exterior syndrome, refers to symptoms that are deeper within (internal organs, qi and blood, bone marrow, etc.). Causes of interior syndrome can generally be categorized into three situations:First, the progression of exterior syndrome, where the exterior pathogen is unresolved and penetrates into the interior, affecting the internal organs; Second, direct invasion of external pathogens into the internal organs, such as abdominal cold or excessive consumption of cold foods leading to interior cold syndrome; Third, internal injuries from emotional disturbances, overexertion, or dietary factors directly causing dysfunction of the internal organs, such as dizziness and pain in the hypochondrium from liver disease, palpitations and shortness of breath from heart disease, cough and wheezing from lung disease, abdominal distension and diarrhea from spleen disease, and low back pain and urinary retention from kidney disease.Therefore, the clinical manifestations of interior syndrome are complex, and all symptoms that are not exterior syndrome belong to interior syndrome. For external diseases, interior syndrome requires consideration of etiology diagnosis and defensive qi, nutritive qi, and blood diagnosis, while for internal injuries and miscellaneous diseases, internal organ diagnosis is the primary focus.Interior syndrome must be distinguished as interior cold, interior heat, interior deficiency, or interior excess (discussed in the context of cold-heat and deficiency-excess diagnosis). Distinguishing between exterior and interior syndromes is primarily based on the patient’s history, the nature of the symptoms, and changes in tongue coating and pulse. Generally, new diseases or those with a short duration are more likely to be exterior syndromes; chronic diseases or those with a long duration are often interior syndromes. Fever and aversion to cold indicate exterior syndrome; fever without aversion to cold or only cold without fever indicate interior syndrome. Tongue coating in exterior syndrome often shows no changes or only slight redness at the edges and tip; interior syndrome often presents with abnormal tongue coating, with a floating pulse indicating exterior syndrome and a deep pulse indicating interior syndrome. (3) Half Exterior Half Interior SyndromeHalf exterior half interior syndrome refers to symptoms that are neither purely exterior nor purely interior, occurring in a state between the two. 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 yellow-white coating, and the pulse is wiry. Pathogenesis: The struggle between righteous and pathogenic qi occurs in the half exterior half interior state, leading to alternating chills and fever. The pathogenic factors invade the half exterior half interior state, affecting the gallbladder meridian, resulting in chest and hypochondriac fullness and a bitter taste. Heat in the gallbladder and disharmony between the liver and stomach lead to irritability, dizziness, nausea, and loss of appetite. Treatment Principle: Harmonize and resolve both exterior and interior. Common Formulas:Xiao Chai Hu Tang (Minor Bupleurum Decoction)(4) Concurrent Exterior and Interior Disease (Mixed Exterior and Interior)Concurrent exterior and interior disease refers to the simultaneous occurrence of exterior and interior syndromes. There are three common situations:First, the initial onset of the disease presents both exterior and interior symptoms. Second, at the onset of the disease, only exterior symptoms are present, but later, as the pathogenic factors penetrate into the interior, interior symptoms appear while exterior symptoms remain unresolved, also referred to as concurrent exterior and interior disease. Third, if the original disease has not resolved, it may also present concurrent symptoms, such as pre-existing internal injuries combined with external pathogens, or initial external diseases that later affect digestion, etc., which also belong to concurrent exterior and interior disease.The treatment principle is to resolve both exterior and interior simultaneously.
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Cold and Heat
Cold and heat are the two principles for distinguishing the nature of diseases, summarizing the conditions of yin and yang in the body. Generally, cold syndromes are manifestations of insufficient yang qi or the invasion of cold pathogens, while heat syndromes are manifestations of excessive yang qi or the invasion of heat pathogens. The saying goes, “Excessive yang leads to heat, excessive yin leads to cold; deficient yang leads to cold, deficient yin leads to heat.” Distinguishing between cold and heat is the basis for using warming or cooling herbs in treatment, as the principle states, “Treat cold with heat, treat heat with cold.” (1) Cold SyndromeCold syndrome refers to symptoms caused by the invasion of cold pathogens (such as cold or damp pathogens) or by yang deficiency and excessive yin, leading to weakened organ function and reduced activity. It can be divided into exterior cold syndrome and interior cold syndrome, with exterior cold syndrome discussed previously; here we refer to interior cold syndrome. 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, frequent urination. The tongue is pale, with a white coating, and the pulse is deep and slow. Pathogenesis: Yang deficiency leads to excessive yin, causing the patient to feel cold; cold in the spleen and stomach leads to abdominal pain relieved by warmth, and weak yang qi results in a deep and slow pulse. Treatment Principle: Warm the middle and dispel cold. Common Formulas:Fu Zi Li Zhong Tang (Aconite Decoction to Regulate the Middle)(2) Heat SyndromeHeat syndrome refers to symptoms caused by the invasion of heat pathogens (such as wind, heat, or fire pathogens) or by excessive yang and deficient yin, leading to hyperactivity of organ function and depletion of body fluids. It can be divided into exterior heat syndrome and interior heat syndrome, with exterior heat syndrome discussed previously; here we refer to interior heat syndrome. 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 urination. The tongue is red, with a yellow coating, and the pulse is rapid. Pathogenesis: Excessive yang leads to fever and a preference for coolness; heat damages body fluids, leading to thirst; heat in the chest and abdomen results in rapid pulse. Treatment Principle: Clear heat. Common Formulas:Bai Hu Tang (White Tiger Decoction)(3) Excess Heat and Deficiency HeatExcess heat syndrome caused by the invasion of heat pathogens differs from deficiency heat syndrome caused by the depletion of body fluids or hyperactivity of organ function, with different clinical manifestations and treatment principles.See the table below 
(4) True Cold and False HeatIn the critical stages of disease development, one can observe phenomena such as “true cold appearing as heat” and “true heat appearing as cold.” Clinically, true heat that manifests as cold symptoms is termed “true heat false cold,” while true cold that manifests as heat symptoms 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 body heat, 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, curls up while lying down, has a pale tongue, black and moist coating, and a floating but weak pulse. This indicates excessive yin internally, with yang constrained externally, thus its essence remains a cold syndrome, therefore termed “true cold false heat.” Treatment should focus on warming the interior and reviving yang, guiding fire back to the source.2. “True Heat False Cold”: This refers to true heat internally while appearing as false cold externally. For instance, in severe heat diseases, one may observe a lack of expression, drowsiness, cold hands and feet, and a deep, thin pulse, which superficially resembles cold syndrome, but there are also signs of heat in the mouth and nose, burning sensation in the chest and abdomen, thirst with a preference for cold drinks, constipation, and short, red urination. The tongue is red, with a yellow, dry coating, and the pulse is thin but rapid and strong. This indicates internal yang heat that cannot express outwardly, thus its essence is a heat syndrome, therefore termed “true heat false cold.” Treatment should focus on clearing internal heat and promoting yang qi.In general, the manifestations of cold and heat are superficial signs, while the internal and underlying conditions of cold and heat represent their essence.Distinguishing between cold and heat syndromes should not be based solely on one symptom or sign; a comprehensive observation of the entire disease presentation is essential, particularly regarding cold and heat, thirst or lack of thirst, complexion, temperature of the limbs, urination, tongue appearance, and pulse characteristics. That is, aversion to cold and preference for warmth indicates cold, while fever and preference for coolness indicate heat; lack of thirst indicates cold, while thirst with a preference for drinking indicates heat; a red complexion indicates heat; cold hands and feet indicate cold, while warm limbs indicate heat; clear, frequent urination and loose stools indicate cold, while short, red urination and constipation indicate heat; a pale tongue with a white coating indicates cold, while a red tongue with a yellow coating indicates heat, etc. From the comparison of cold and heat syndromes, it can be seen that cold syndromes are associated with excessive yin and often co-occur with yang deficiency, while heat syndromes are associated with excessive yang and often present with signs of yin fluid depletion.
3
Deficiency and Excess
Deficiency and excess are the two principles for distinguishing the strength of the body’s righteous qi and the severity of pathogenic qi. Generally, deficiency refers to insufficient righteous qi, and deficiency syndrome manifests as symptoms of insufficient righteous qi, while excess refers to excessive pathogenic qi, and excess syndrome manifests as symptoms 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 syndrome indicates insufficient righteous qi, while pathogenic qi is not strong; excess syndrome indicates excessive pathogenic qi, while righteous qi is still present, reflecting a fierce struggle between the two. Distinguishing between deficiency and excess is the basis for determining whether to tonify (supplement deficiency) or drain (reduce excess) in treatment, as the principle states, “Deficiency should be supplemented, excess should be drained.”(1) Deficiency SyndromeDeficiency syndrome can arise from a weak constitution (either congenital or acquired), prolonged illness damaging righteous qi, excessive blood loss, loss of essence, excessive sweating, or invasion of external pathogens damaging righteous qi, leading to “vital qi being depleted.”Main Symptoms: pale or sallow complexion, mental fatigue, physical weakness, palpitations, shortness of breath, cold limbs, or five hearts feeling hot, spontaneous sweating, night sweats, loose stools, frequent urination, pale tongue with little or no coating, and weak pulse. Clinically, due to insufficient qi, blood, yin, or yang, deficiency syndromes can be categorized into qi deficiency, blood deficiency, yin deficiency, and yang deficiency, as well as deficiency syndromes of specific organs (such as lung qi deficiency, heart blood deficiency, liver yin deficiency, spleen qi deficiency, kidney yang deficiency, etc.).Table of Symptoms and Treatment Principles for Qi Deficiency, Blood Deficiency, Yin Deficiency, and Yang Deficiency
From the above table, it can be seen that qi deficiency and yang deficiency both indicate insufficient yang qi, thus presenting similar clinical manifestations, including pale complexion, fatigue, and spontaneous sweating. However, they differ in that qi deficiency does not present with “cold symptoms,” while yang deficiency presents with “cold symptoms” such as aversion to cold, cold limbs, and a slow pulse.Blood deficiency and yin deficiency both indicate insufficient yin fluids, thus presenting similar clinical manifestations, including weight loss, dizziness, palpitations, and insomnia. However, they differ in that blood deficiency does not present with “heat symptoms,” while yin deficiency presents with signs of yin fluid depletion leading to yang hyperactivity, thus presenting “heat symptoms” such as low-grade fever or tidal fever, dry mouth, and dry throat.(2) Excess SyndromeExcess syndrome can arise from a robust constitution of the patient, sudden illness due to external pathogen invasion, or dysfunction of internal organs leading to the accumulation of pathological products such as qi stagnation, blood stasis, phlegm, dampness, food stagnation, or parasitic accumulation.Clinical manifestations vary based on the nature of the pathogenic factors and the internal organs affected, characterized by excessive pathogenic qi, weakened righteous qi, and a fierce struggle between the two. Common symptoms include high fever, flushed face, irritability, delirium, loud voice, abdominal distension and pain with refusal to be touched, excessive phlegm, constipation, difficulty urinating, or the presence of blood stasis, swelling, water retention, food stagnation, or parasitic accumulation, with thick, greasy tongue coating and a strong pulse.Treatment Principle:Draining excess and attacking pathogenic factors is the main method for treating excess syndrome, as the principle states, “Excess should be drained.” However, different methods of draining, such as clearing heat, promoting bowel movements, draining water, dispelling phlegm, regulating qi, invigorating blood, and eliminating food stagnation or parasites, will be discussed in relevant sections.Distinguishing between deficiency and excess syndromes can be considered from the following aspects:From the onset time, new diseases, initial diseases, or those with a short duration are often excess syndromes, while chronic diseases or those with a long duration are often deficiency syndromes;From the etiology, external pathogens are often excess syndromes, while internal injuries are often deficiency syndromes;From the constitution, younger, robust individuals are often excess syndromes, while older, weaker individuals are often deficiency syndromes;From clinical symptoms and signs, refer to the table below for differentiation.
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Yin and Yang
Yin and yang are the two principles for distinguishing the nature of diseases, serving as the overarching framework for the Eight Principles, summarizing exterior and interior, cold and heat, deficiency and excess. The “Classified Treatise on Yin and Yang” states, “In human diseases, there must be a basis, either based on yin or based on yang. Although the manifestations are numerous, their essence is one,” indicating that although symptoms may be complex and varied, they ultimately fall into the two categories of yin and yang, and the key to diagnosing diseases must first clarify whether they belong to yin or yang. Therefore, yin and yang serve as the overarching framework for the Eight Principles, generally, exterior, excess, and heat syndromes belong to yang syndromes, while interior, deficiency, and cold syndromes belong to yin syndromes. The clinical manifestations, etiology, pathogenesis, and treatment of yin and yang syndromes have been discussed within the context of exterior-interior, cold-heat, and deficiency-excess principles. However, clinically, yin syndromes often refer to interior deficiency cold syndromes, while yang syndromes often refer to interior excess heat syndromes.(1) Yin SyndromeYin syndrome refers to the condition of deficient yang qi and excessive yin. Generally, yin syndromes are characterized by cold symptoms, such as aversion to cold, absence of fever, cold limbs, mental fatigue, and a deep, weak pulse. This is often due to the low function of internal organs and a weakened response of the body, commonly seen in older, weaker individuals or those with chronic illnesses, presenting a picture of deficiency cold.(2) Yang SyndromeYang syndrome refers to the condition of excessive yang qi and preserved righteous qi. Generally, yang syndromes are characterized by heat symptoms, such as fever, aversion to heat, warm limbs, irritability, thirst, and a rapid, strong pulse. This is often due to the hyperactivity of internal organ functions, commonly seen in robust individuals, new diseases, or initial diseases, presenting a picture of excess heat.The main clinical manifestations of yin and yang syndromes can be referenced in the table below:
(3) Loss of Yin and Loss of YangLoss of yin and loss of yang are two dangerous syndromes that can occur during the disease process, often seen in cases of high fever, continuous sweating, severe vomiting and diarrhea, or excessive blood loss, leading to rapid loss of yin fluids or yang qi. These are commonly seen in patients in shock. Although loss of yin and loss of yang fall under the category of deficiency syndromes, they are distinguished from general deficiency syndromes 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, also exhibit varying degrees of sweating.However, loss of yin sweating is characterized by hot and sticky sweat, along with hot skin, warm hands and feet, thirst with a preference for drinking, and a rapid, thin pulse that is weak upon palpation, indicating depletion of yin and extreme yang; loss of yang sweating is characterized by profuse sweating, cool and non-sticky sweat, along with aversion to cold, lethargy, cold limbs, and a weak pulse that is barely palpable, indicating loss of yang and excessive 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 transitions occurring between them, only differing in their primary and secondary characteristics.The treatment for loss of yin and loss of yang focuses on tonifying the righteous qi and stabilizing the condition. For loss of yin, one should tonify qi and nourish yin, generating fluids to prevent loss of yang, commonly using formulas such as Sheng Mai San (Generate the Pulse Powder); for loss of yang, one should tonify qi and stabilize the condition, commonly using formulas such as Du Shen Tang (Ginseng Decoction) and Shen Fu Tang (Ginseng and Aconite Decoction).The treatment for loss of yin and loss of yang can be referenced in the table below.
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The Interrelationship of the Eight Principles and the Application of Eight Principles Diagnosis
The distinctions between exterior and interior, cold and heat, deficiency and excess are not merely isolated, static categories, but are 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. For example, in the early stages of an external heat disease, one may observe exterior symptoms, but further differentiation is needed to determine whether it is accompanied by cold or heat, thus categorizing it into exterior cold syndrome or exterior heat syndrome; in chronic diseases, deficiency syndromes often require further differentiation to determine whether they are deficiency cold or deficiency heat syndromes.When symptoms of coexistence appear, they should not be treated equally, as there is a primary and secondary relationship. For instance, both exterior cold and exterior heat syndromes are primarily exterior syndromes, with cold or heat being secondary to the exterior syndrome, thus treatment should primarily focus on releasing the exterior, using warm acrid herbs for exterior cold or cool acrid herbs for exterior heat; deficiency cold and deficiency heat syndromes are primarily deficiency syndromes, with cold or heat being secondary to the deficiency syndrome, thus treatment should primarily focus on tonifying deficiency, using yang tonics or yin tonics accordingly.In cases of coexistence between exterior and interior, the primary syndrome must 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 concurrent exterior and interior disease). Additionally, during the progression of a disease, false appearances may arise, such as true heat appearing as false cold or true cold appearing as false heat. Therefore, during the diagnostic process, careful observation and comprehensive analysis are necessary to discern the truth from the false, grasp the essence, and avoid misdiagnosis and mistreatment, which could delay treatment.(3) Transformation“Transformation” refers to the transition 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 not only oppositional but can also transform into one another under certain conditions. For example, exterior cold symptoms such as aversion to cold and fever may develop into interior heat syndrome if the condition progresses or if treatment is inappropriate; excess syndromes may transform into deficiency syndromes due to misdiagnosis or inadequate treatment, where the pathogenic qi gradually diminishes but the righteous qi is also harmed, leading to a gradual transformation into deficiency syndrome. Conversely, deficiency syndromes may give rise to various excess syndromes due to insufficient righteous qi, leading to the generation of phlegm, dampness, qi stagnation, or blood stasis, resulting in various excess syndromes. Transformation can only occur under certain conditions, and during diagnosis, it is essential to continuously observe changes in the pathogenesis, diagnose and treat promptly to prevent the disease from worsening and to promote recovery.When applying the Eight Principles of Diagnosis, first distinguish between exterior and interior to determine the location of the disease;then differentiate cold and heat, deficiency and excess, clarifying the nature of the disease and understanding the comparative strength of the righteous and pathogenic forces;finally, summarize using yin and yang.
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Conclusion
The Eight Principles of Diagnosis is a method for diagnosing diseases by summarizing and analyzing from the perspectives of exterior and interior, cold and heat, deficiency and excess, and yin and yang. Although it should be combined with etiology diagnosis, defensive qi, nutritive qi, and blood diagnosis for a more comprehensive diagnosis, it serves as the foundation for various diagnostic methods, playing a role in simplifying complexity and summarizing key points.The Eight Principles are not fixed but can transform under certain conditions; exterior syndromes progressing to interior indicate worsening of the disease, while interior syndromes resolving to exterior indicate improvement; heat syndromes transforming into cold syndromes and excess syndromes transforming into deficiency syndromes often indicate that the righteous qi is unable to overcome the pathogenic qi, while cold syndromes transforming into heat syndromes and deficiency syndromes transforming into excess syndromes often indicate a gradual recovery of righteous qi.Although the Eight Principles have distinct manifestations, they are rarely isolated and often exhibit complex relationships of “coexistence” and “mixing,” and may sometimes present “false appearances.” Therefore, during the diagnostic process, it is crucial to conduct thorough investigations, think coherently, grasp the essence through the phenomena, and timely recognize the transformations of the disease; only in this way can accurate analysis, correct diagnosis, and appropriate treatment be achieved.⊙ The content of this article is for clinical reference only; non-TCM professionals should not attempt to use herbs.
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