Comprehensive Guide to the Eight Principles of Diagnosis in TCM

1. Concept
1. Eight Principles: Refers to the eight diagnostic principles of biāo (exterior), lǐ (interior), hán (cold), rè (heat), xū (deficiency), shí (excess), yīn (yin), and yáng (yang).
2. Eight Principles Diagnosis: This is the process by which a physician uses the theory of the Eight Principles to analyze and synthesize various clinical data obtained through observation, listening, questioning, and pulse-taking, in order to discern the depth of the disease location, the nature of the disease as cold or heat, the strength of the pathogenic and righteous qi, and the yin-yang classification of the disease.2. Basic Syndromes of the Eight Principles
1. Exterior and Interior Diagnosis: The distinction between exterior and interior is a pair of principles used to identify the depth of the disease location and the progression of the disease. In a narrow sense, biāo refers to the skin, muscles, and meridians as the exterior, while zàng (organs), sǔi (marrow) are considered the interior. A disease on the exterior is classified as biāo, indicating a lighter condition; a disease in the interior is classified as lǐ, indicating a more severe condition. The distinction between exterior and interior is particularly important for exogenous diseases.
1) Exterior Syndrome: Refers to the light symptoms resulting from the invasion of external pathogenic factors such as the six excesses, epidemics, and insect toxins through the skin and mucous membranes, where the righteous qi resists the pathogenic factors, leading to a loss of the defensive qi. Clinical manifestations include aversion to cold (or wind), fever (or subjective feeling of fever), body aches, thin white tongue coating, and floating pulse. Symptoms may also include nasal congestion, clear nasal discharge, sneezing, itchy or sore throat, and slight cough.
2) Interior Syndrome: Refers to symptoms indicating that the disease is located internally, affecting the organs, qi, blood, or marrow. Causes include:
(1) External pathogenic factors invading the exterior and then penetrating to the interior, forming an interior syndrome.
(2) External pathogenic factors directly entering the interior, invading the organs, known as “zhí zhōng” (directly affecting).
(3) Internal injuries from emotions, diet, or overwork, directly damaging the organs, or affecting qi, blood, and body fluids.
Clinical manifestations: Due to the complex causes of interior syndromes, symptoms can vary widely. The basic characteristics include the absence of new onset of aversion to cold and fever, or only cold without heat, or only heat without cold, with organ symptoms as the main manifestation, such as high fever, irritability, delirium, abdominal pain, diarrhea, vomiting, constipation, thick tongue coating, and changes in tongue quality, with a deep pulse.
3) Half Exterior Half Interior Syndrome: Refers to a condition where the exogenous pathogenic factors are neither fully in the exterior nor have completely entered the interior, with the pathogenic and righteous qi contending between the exterior and interior, often seen in shào yáng (lesser yang) disorders.
2. Cold and Heat Diagnosis: Cold and heat are a pair of principles used to identify the nature of the disease.
1) Cold Syndrome: Refers to symptoms resulting from the invasion of cold pathogenic factors or the predominance of yin over yang. Shí hán (excess cold syndrome): Refers to the invasion of cold pathogenic factors or excessive consumption of cold foods, with sudden onset and in individuals with strong constitution.
Xū hán (deficiency cold syndrome): Refers to internal injuries from prolonged illness, where yang qi is depleted and internal cold develops, also known as yáng xū (yang deficiency syndrome).
Biāo hán (exterior cold syndrome): Refers to cold pathogenic factors attacking the skin surface.
Lǐ hán (interior cold syndrome): Refers to cold pathogenic factors affecting the organs or due to deficiency of yang qi in the organs. Clinical manifestations: Various types of cold syndromes may present differently, commonly seen are: aversion to cold, preference for warmth, cold pain, desire for warmth, cold limbs, pale complexion, thin white tongue coating, and slow or tight pulse.
2) Heat Syndrome: Refers to symptoms resulting from the invasion of heat pathogenic factors or the predominance of yang over yin, leading to hyperactivity of the body’s functions. Shí rè (excess heat syndrome): Refers to invasion by fire or yang pathogenic factors, excessive consumption of spicy and warm foods, excessive emotional stress leading to heat, or excessive internal yang heat. The condition is acute and the body is robust.
Xū rè (deficiency heat syndrome): Refers to internal injuries from prolonged illness or sexual activity, leading to depletion of yin fluids and excessive yang, also known as yīn xū (yin deficiency syndrome).
Biāo rè (exterior heat syndrome): Refers to wind-heat pathogenic factors invading the skin surface.
Lǐ rè (interior heat syndrome): Refers to heat pathogenic factors prevailing in the organs or due to deficiency of yin fluids. Clinical manifestations: Various types of heat syndromes may present differently, commonly seen are: fever, aversion to heat, preference for cold, thirst for cold drinks, yellow and thick phlegm, short yellow urine, dry and hard stools, red complexion, red tongue with yellow coating, and rapid pulse.
3) Deficiency and Excess Diagnosis: Deficiency and excess are a pair of principles used to identify the strength of the righteous and pathogenic qi, reflecting the dynamics of the disease process.
1) Excess Syndrome: Refers to the body’s response to external pathogenic factors, accumulation of pathological products, or excess, stagnation, or hyperactivity of yin and yang qi, characterized by various clinical manifestations. Characteristics: Pathogenic qi is abundant while righteous qi is not deficient, with intense contention between the pathogenic and righteous qi. Clinical manifestations vary based on the nature of the pathogenic factors and pathological products, with symptoms reflecting the location of the pathogenic invasion and accumulation.
3. Relationship Between the Eight Principles Syndromes: 1) Syndrome Combination: Broadly refers to the coexistence of various syndromes. Narrowly refers to the comprehensive judgment of the disease from different perspectives such as exterior-interior, cold-heat, deficiency-excess, etc., to reveal the essence of the disease. Biāo xū syndrome: Refers to exterior syndrome with sweating. Its actual meaning has two aspects: exterior deficiency due to invasion of wind, with clinical manifestations of aversion to wind, fever, spontaneous sweating, headache, and floating pulse. Internal injury leading to exterior deficiency due to spleen and lung qi deficiency, with symptoms of spontaneous sweating, susceptibility to colds, pale complexion, shortness of breath upon exertion, loose stools, fatigue, pale tongue with white coating, and weak pulse. Biāo shí hán syndrome: Refers to exterior cold syndrome with pathogenic factors invading the exterior, with clinical manifestations of aversion to cold, fever, no sweating, headache, and tight floating pulse. Biāo shí rè syndrome: Refers to exterior heat syndrome with clinical manifestations of fever, slight aversion to wind, no sweating or little sweating, slight thirst, red tongue with thin white coating, and floating rapid pulse. Lǐ shí hán syndrome: Refers to interior cold syndrome with clinical manifestations of aversion to cold, cold pain in the abdomen or lower back, preference for warmth, vomiting, diarrhea, cough, asthma, clear long urine, pale complexion, white tongue coating, and deep slow pulse. Lǐ shí rè syndrome: Refers to interior heat syndrome with clinical manifestations of high fever, aversion to heat, thirst for cold drinks, red complexion, red tongue with yellow coating, and rapid pulse. Lǐ xū hán syndrome: Refers to internal deficiency cold syndrome with clinical manifestations of cold limbs, pale complexion, and deep slow pulse. Lǐ xū rè syndrome: Refers to internal deficiency heat syndrome with clinical manifestations of fever, aversion to cold, and red tongue with little coating. 2) Syndrome Complexity: Refers to the simultaneous appearance of opposing syndromes at a certain stage of the disease. 1) Exterior and Interior Coexisting Disease: Refers to the simultaneous appearance of exterior and interior syndromes at a certain stage of the disease. Causes include:
(1) Initial disease showing both exterior and interior syndromes.
(2) Exterior syndrome not resolved, leading to interior involvement.
(3) Original disease not cured, with additional exterior disease. Common types include:
(1) Exterior and interior diseases with no contradiction in cold-heat and deficiency-excess syndromes. Biāo shí hán and Lǐ shí hán syndromes.
(2) Exterior and interior diseases with the same cold-heat nature but opposite deficiency-excess nature. Biāo shí hán and Lǐ xū hán syndromes.
(3) Exterior and interior diseases with the same deficiency-excess nature but opposite cold-heat nature, such as Biāo shí hán and Lǐ shí rè syndromes.
3) Cold and Heat Complexity: Refers to the simultaneous existence of cold and heat syndromes. 1) Exterior and Interior Cold-Heat Complexity: Biāo hán and Lǐ rè syndromes, Biāo shí hán and Lǐ shí rè syndromes. 2) Up and Down Cold-Heat Complexity: Upper heat and lower cold (e.g., heat in the upper jiao and cold in the middle jiao), or lower heat and upper cold (e.g., cold in the stomach and heat in the bladder).
3) Deficiency and Excess Complexity: Refers to the simultaneous presence of both deficiency and excess syndromes, often seen in severe cases. 1) Excess Syndrome with Deficiency: Refers to a condition where excess pathogenic factors dominate, while deficiency is secondary. Commonly seen in patients with excess syndromes where the righteous qi is damaged or those with a weak constitution who are newly affected by external pathogenic factors. 2) Deficiency Syndrome with Excess: Refers to a condition where deficiency is primary and excess is secondary. Commonly seen in patients with prolonged excess syndromes where the righteous qi is severely damaged, but residual pathogenic factors remain, or those with a weak constitution who are newly affected by pathogenic factors. 3) Equal Deficiency and Excess: Refers to a condition where both deficiency and excess are evident, often seen in severe cases of excess syndromes where the righteous qi is severely damaged or the original righteous qi is weak, and the patient is affected by heavy pathogenic factors.
4) Transformation of Syndromes: Refers to the transformation of one syndrome into another under certain conditions. 1) Exterior and Interior Transformation:
(1) Exterior syndrome entering the interior: Refers to the initial appearance of exterior syndrome followed by the emergence of interior syndrome, with the exterior syndrome subsequently disappearing. This is generally seen in the early to mid-stages of exogenous diseases, reflecting the progression of the disease from superficial to deep.
(2) Interior pathogenic factors emerging to the exterior: Refers to certain interior syndromes where the pathogenic factors have a tendency to reach the exterior. This does not mean that the interior syndrome transforms into an exterior syndrome. Generally, this indicates a favorable trend for the disease to improve.
2) Cold and Heat Transformation:
(1) Cold syndrome transforming into heat: Refers to a condition that was originally cold, later presenting with heat symptoms, while the cold symptoms subsequently disappear. This often occurs due to improper treatment, excessive consumption of warming and drying substances, or failure to treat the external cold in a timely manner, leading to an internal accumulation of yang heat.
(2) Heat syndrome transforming into cold: Refers to a condition that was originally heat, later presenting with cold symptoms, while the heat symptoms subsequently disappear. This often occurs due to improper treatment, damage to yang qi, or excessive pathogenic factors overwhelming the righteous qi, leading to a decline in function and loss of yang qi, transforming into a deficiency cold syndrome, or even manifesting as a loss of yang syndrome.
3) Transformation of Deficiency and Excess:
(1) Excess syndrome transforming into deficiency: Refers to a condition that initially presented as an excess syndrome, which, due to improper treatment, prolonged retention of pathogenic factors, or a prolonged course of illness, leads to damage to the righteous qi, resulting in a gradual transformation into a deficiency syndrome.
(2) Deficiency syndrome transforming into excess: Refers to a condition that was originally a deficiency syndrome, which, due to active treatment, rest, and exercise, gradually restores the righteous qi, contending with the pathogenic factors to expel them, presenting as an excess syndrome. Alternatively, a patient with a pre-existing deficiency syndrome may be newly affected by external pathogenic factors, or suffer from food injury or trauma, presenting with excess symptoms that temporarily overshadow the deficiency symptoms. If the original condition was a deficiency syndrome, due to insufficient righteous qi, abnormal qi transformation may lead to the accumulation of pathological products, presenting certain excess symptoms, which should not be interpreted as a transformation from deficiency to excess, but rather as a mixed deficiency-excess condition.
4) True and False Syndromes: Refers to certain diseases that may present false symptoms that contradict the true nature of the disease during critical stages. The so-called “true” refers to symptoms that align with the internal essence of the disease, while “false” refers to symptoms that do not conform to the internal essence of the disease.
1) Cold and Heat True and False:
(1) True heat with false cold: Refers to a condition where there is true heat internally, but false cold symptoms are observed externally. This is known as “yáng shèng gé yīn syndrome” (yang excess with yin constraint). Pathogenesis: Internal yang heat is abundant, but constrained externally, leading to internal closure of yang qi and inability to reach the extremities. Clinical manifestations: Externally resembling a cold syndrome—cold limbs, aversion to cold, mental confusion, dark purple complexion, and deep slow pulse (or thin rapid pulse). The essence is an excess heat syndrome—cold limbs but burning heat in the chest and abdomen, burning sensation in the mouth and nose, foul breath, thirst for cold drinks, short red urine, dry or hard stools, red tongue with yellow coating, and strong pulse.
(2) True cold with false heat: Refers to a condition where there is true cold internally, but false heat symptoms are observed externally. This is known as “yīn shèng gé yáng syndrome” (yin excess with yang constraint). Pathogenesis: Prolonged illness leads to deficiency of yang qi, with internal cold predominating, forcing the deficient yang to float upwards and become constrained externally. Clinical manifestations: Externally resembling a heat syndrome—subjective feeling of heat, desire to remove clothing, flushed complexion, mental agitation, thirst, and floating large pulse. The essence is a deficiency of yang qi—no burning sensation in the chest and abdomen, cold limbs, clear long urine (or reduced urination), or diarrhea with clear stools, pale tongue, etc.
2) True deficiency with false excess: Refers to a condition where the essence is a deficiency syndrome, but false excess symptoms are observed. This is known as “dà xū yǒu yíng zhuàng syndrome” (great deficiency with excess appearance). Pathogenesis: Significant accumulation and obstruction lead to stagnation of qi and blood, resulting in symptoms resembling a deficiency syndrome, such as mental dullness, fatigue, weakness, and thin pulse. Diagnosis: Although the patient may appear silent, when they speak, their voice is loud and strong; although they may seem fatigued, they feel comfortable when moved; although they may appear emaciated, their abdomen is hard and full; although the pulse may be thin, it is strong upon palpation, indicating that the essence of the disease is excess, while the deficiency is a false appearance.
True deficiency with false excess: Refers to a condition where the essence is a deficiency syndrome, but false excess symptoms are observed. This is known as “zhì xū yǒu shèng hòu syndrome” (extreme deficiency with excess appearance). Pathogenesis: Organ deficiency leads to insufficient qi and blood, resulting in symptoms such as abdominal distension, shortness of breath, and constipation. Diagnosis: Although the abdomen may be distended, it may relieve at times; although the patient may be short of breath, their breathing may be weak; although the stools may be constipated, the abdomen may not be hard; and the pulse must be weak, with a pale tongue, and signs of fatigue, pale complexion, etc., indicating that the symptoms are merely a false appearance.
1. Key Points for Differentiating Exterior and Interior Syndromes:
1) Cold and Heat Symptoms: Fever and aversion to cold appearing simultaneously indicate an exterior syndrome; however, fever without aversion to cold or aversion to cold without fever indicates an interior syndrome; alternating cold and heat indicates a half exterior half interior syndrome.
2) Tongue Appearance: The tongue coating in exterior syndromes does not change significantly, while the tongue coating and quality in interior syndromes often show changes.
3) Pulse Appearance: Floating pulse is often seen in exterior syndromes, while deep pulse is often seen in interior syndromes.
2. Differentiating Aversion to Cold, Fever, and Cold and Heat Syndromes:
1) Aversion to cold and fever are phenomena of the disease, while the cold and heat manifestations of the disease can be true or false.
2) Cold and heat syndromes are judgments of the essence of the disease and cannot be isolated based solely on individual symptoms such as aversion to cold, fear of cold, or fever.
3. Key Points for Differentiating Cold and Heat Syndromes:
Cold and Heat Syndrome Differentiation Table

4. Key Points for Differentiating Deficiency and Excess Syndromes:
Understand the characteristics of the disease. Generally, manifestations characterized by insufficient, declining, or relaxed righteous qi are mostly deficiency syndromes; manifestations characterized by excess, solidity, or strength are mostly excess syndromes. During the four examinations, pay attention to the observation of the tongue’s age, the sound of the voice, the duration of the illness, the severity of pain, and the strength of the pulse. A pale tongue indicates excess, while a plump tongue indicates deficiency; a loud voice indicates excess, while a weak voice indicates deficiency; initial onset of exogenous diseases is often excess, while prolonged illness often leads to deficiency; severe pain that resists pressure indicates excess, while dull pain that is relieved by pressure indicates deficiency.
5. Yin and Yang as the Framework for Syndromes: Yin and yang represent two opposing aspects of things, and their application is extensive, encompassing the entire disease process as well as the analysis and summarization of each symptom. Based on the basic properties of yin and yang in the theory, the nature of the disease, clinical syndromes, and specific symptoms can generally be categorized as either yin or yang. For example, in the Eight Principles, biāo, lǐ, hán, rè, xū, and shí reveal different aspects of the disease process, such as disease location, nature, and the dynamics of pathogenic and righteous qi, each representing a characteristic of the disease. They cannot reflect the entire picture of the disease. The six principles in the Eight Principles are equal and cannot replace or substitute for each other. However, yin and yang serve as the overarching framework for the Eight Principles, providing the most basic and general summary and categorization of syndromes. That is, biāo, rè, and shí belong to yang, while lǐ, xū, and hán belong to yin. Thus, yin and yang are the general framework of the Eight Principles, summarizing the types of syndromes.
6. Differentiating Between Loss of Yin and Loss of Yang: Based on the quality of sweat (thin and cold like water or sticky and hot like oil), body temperature (cool or hot), complexion (pale or red), pulse (weak or rapid), etc.
Table for Differentiating Between Loss of Yin and Loss of Yang

7. Why There Are Interrelationships Between the Eight Principles Syndromes: The Eight Principles of biāo, lǐ, hán, rè, xū, shí, yīn, and yáng summarize the essence of the disease from various aspects. However, the various aspects of the pathological essence are interconnected; that is, the nature of cold and heat, the contention between pathogenic and righteous qi cannot exist independently of the exterior and interior disease locations, nor can exterior or interior syndromes exist independently of the nature of cold, heat, deficiency, or excess. Therefore, the Eight Principles syndromes cannot be analyzed, judged, or classified in isolation, as they can coexist, be mixed, or exist in intermediate states, and they continuously change with the development of the disease. In clinical diagnosis, it is essential to recognize not only the basic syndromes of the Eight Principles but also the interrelationships between them. Only by connecting the Eight Principles can a comprehensive analysis of the disease be conducted, leading to a more complete and accurate understanding of the syndromes.
8. The Significance of the Transformation Between Cold and Heat Syndromes: The transformation between cold and heat reflects the contrast between the forces of pathogenic and righteous qi, with the key being the fluctuation of the body’s yang qi. The transformation of cold into heat indicates that the righteous qi is still strong enough to resist the pathogenic qi, with yang qi being relatively abundant, leading to the transformation of the pathogenic qi into heat. The transformation of heat into cold indicates that the pathogenic qi is too strong for the righteous qi to support, leading to the depletion of yang qi and indicating that the righteous qi cannot overcome the pathogenic qi, resulting in a severe condition.
9. Differentiating Between True and False Cold and Heat: The appearance of false symptoms often occurs in the limbs, skin, and complexion, while the internal manifestations of the organs, qi, blood, and body fluids, as well as changes in tongue and pulse, are often the true reflection of the disease essence and can serve as diagnostic criteria. False symptoms differ from true symptoms and should be carefully distinguished. For example, although the patient may feel thirsty, they may not want to drink; although the throat may feel sore, it may not be red or swollen; although the patient may feel agitated, they may also feel fatigued and weak; although the pulse may be floating or rapid, it may be weak upon palpation; although the complexion may occasionally appear flushed, it may not be uniformly red, indicating that the “heat” is a false appearance.
10. Differentiating Between True and False Deficiency and Excess: The strength or weakness of the pulse, the vitality of the patient, and the quality of the tongue are key indicators. The quality of the tongue can indicate whether it is plump or thin, while the voice can indicate whether it is strong or weak. The patient’s constitution, the duration of the illness, and the treatment history are also important factors for differentiation.
1. Etiological Diagnosis:
1) Exterior Wind Syndrome: Refers to a type of syndrome caused by the invasion of external wind pathogenic factors into the skin, muscles, meridians, organs, and qi and blood, characterized by sudden onset, rapid changes, and erratic symptoms.
2) Interior Wind Syndrome: Refers to symptoms resembling “moving wind” caused by pathological changes such as excessive heat damaging the tendons, blood deficiency, yin deficiency leading to loss of nourishment to the tendons, or excessive yang leading to symptoms such as dizziness, numbness, itching, or tremors. Clinical manifestations include:
(1) Wind invading the exterior: aversion to wind and cold, slight fever, spontaneous sweating, nasal congestion or sneezing, cough, itchy or sore throat, thin white tongue coating, and floating pulse.
(2) Wind entering the skin: new onset of skin itching, possibly with papules or wheals.
(3) Wind invading the meridians: sudden facial numbness, crooked mouth, stiff neck, inability to open the mouth, or even convulsions of the limbs.
(4) Wind injuring the joints: joint pain that is erratic and migratory.
(5) Wind-water interaction: sudden swelling of the face, eyelids, or limbs.
Common exterior wind syndromes include: wind invading the exterior (taiyang wind), wind affecting the skin, wind invading the lungs, wind-water interaction, wind invading the meridians, and wind toxin invading the meridians. Mixed syndromes include: wind-cold, wind-heat, wind-fire, wind-damp, wind-phlegm, wind-water, and wind-toxin syndromes.
2) Excess Cold Syndrome: Refers to a type of syndrome caused by exposure to rain, water, thin clothing, sleeping outdoors, consuming raw or cold foods, leading to damage to the body’s yang qi and obstruction of qi and blood flow. It is characterized by sudden onset and severe symptoms, often with identifiable causes of cold exposure. Shāng hán syndrome: Refers to the invasion of cold pathogenic factors affecting the skin, obstructing the defensive yang, and the righteous qi resisting the pathogenic factors externally, presenting as an exterior excess cold syndrome. Also known as exterior cold syndrome, cold pathogenic factors binding the exterior syndrome, or taiyang cold syndrome. Zhōng hán syndrome: Refers to cold pathogenic factors directly invading the interior, damaging or obstructing the yang qi, and obstructing the flow of qi and blood, presenting as an interior excess cold syndrome, also known as interior cold syndrome. Clinical manifestations include:
(1) Cold damage: sudden aversion to cold, slight fever, body aches, no sweating, nasal congestion with clear discharge, no thirst, thin white tongue coating, and floating tight pulse, or cold limbs, stiffness, and joint pain.
(2) Interior cold: sudden aversion to cold, cold pain in the abdomen or lower back, preference for warmth, possible vomiting or diarrhea, cough, asthma, clear long urine, pale complexion, white tongue coating, and deep slow pulse.
Common excess cold syndromes include: cold binding the exterior syndrome (taiyang cold syndrome), cold affecting the lungs, cold obstructing the stomach and intestines, cold obstructing the liver meridian, cold obstructing the heart meridian, cold obstructing the uterus, and cold bi syndrome (painful bi syndrome). Mixed syndromes include: wind-cold, cold-damp, cool dryness, cold phlegm, and cold drink syndromes. Evolution: excess cold syndrome → deficiency cold syndrome → loss of yang syndrome.
3) Summer Heat Syndrome: Refers to a type of syndrome caused by the invasion of summer heat pathogenic factors during the hot summer season. Although its nature is similar to fire heat, summer heat has strict seasonal characteristics, and its pathogenesis and syndromes differ from general fire heat syndromes. Clinical manifestations include:
(1) Summer heat injuring the qi: aversion to heat, sweating, thirst, shortness of breath, fatigue, and heavy limbs, with short red urine, red tongue, yellow or white coating, and rapid pulse.
(2) Summer heat obstructing qi: may also present with chest tightness, abdominal pain, nausea, and absence of sweating.
(3) Summer heat obstructing the spirit: may present with confusion or convulsions.
Common summer heat syndromes include: summer damp invading the exterior syndrome, summer heat injuring the qi syndrome (heat stroke), summer heat obstructing qi syndrome, and summer heat obstructing the spirit syndrome (heat stroke).
4) Damp Syndrome: Refers to a pathological substance that is either externally invading the body or internally resulting from abnormal fluid metabolism, presenting as a diffuse pathological state. Clinical manifestations are characterized by heaviness, fullness, soreness, and turbidity, with a tendency for chronicity. External dampness: heaviness in the head, heaviness and pain in the limbs and joints, or skin itching, possibly with slight aversion to cold and mild fever. Internal dampness: chest tightness, poor appetite, nausea, or vomiting, heaviness and drowsiness, or loose stools, with a muddy complexion, slippery tongue coating, and soft pulse. Common damp syndromes include: damp obstructing the defensive exterior syndrome (exterior damp syndrome), cold damp obstructing the tendons and bones syndrome (damp bi syndrome), damp obstructing the spleen yang syndrome, damp-heat accumulating in the spleen syndrome, liver-gallbladder damp-heat syndrome, intestinal damp-heat syndrome, bladder damp-heat syndrome, damp-heat descending syndrome, and damp phlegm affecting the head syndrome. Mixed syndromes include: cold damp, damp-heat, wind-damp, summer damp, water damp, phlegm damp, and damp toxin syndromes.
5) Dryness Syndrome: Refers to symptoms caused by external dryness invading the body, leading to the consumption of body fluids. Internal dryness refers to symptoms caused by insufficient body fluids, belonging to the category of qi, blood, and body fluid differentiation. Clinical manifestations include:
(1) External dryness: dry skin, possibly cracking or peeling, dry lips, nasal passages, and throat, dry tongue coating, thirst for water, with pulse often showing no specific changes or thin and rough.
(2) Dryness injuring the lungs: may present with dry cough with little phlegm, sticky phlegm that is difficult to expectorate, short urination, and dry stools.
Common dryness syndromes include: cool dryness, warm dryness, dryness invading the exterior syndrome, dryness injuring the lungs syndrome, and dryness affecting the clear orifices syndrome.
6) Fire Heat Syndrome: Refers to syndromes characterized by warmth and heat, with similar concepts to heat syndromes. Fire heat syndromes can be divided into excess heat (real fire) and deficiency heat (false fire). Excess heat (real fire) syndrome refers to symptoms caused by external yang heat invading or excessive internal yang heat. It is characterized by sudden onset and severe symptoms. Deficiency heat (false fire) syndrome refers to symptoms of internal heat due to yin deficiency. Clinical manifestations include: fever, aversion to heat, irritability, thirst for cold drinks, excessive sweating, dry stools, short yellow urine, red complexion, red tongue with yellow or gray-black coating, and rapid pulse. Severe cases may lead to various bleeding, abscesses, or ulcers, or severe symptoms such as heat-induced wind or heat obstructing the spirit. Common excess heat (real fire) syndromes include: wind-heat invading the exterior syndrome, lung heat blazing syndrome, heart fire excess syndrome, stomach heat blazing syndrome, heat disturbing the chest syndrome, intestinal heat excess syndrome, liver fire rising syndrome, liver fire invading the lungs syndrome, heat obstructing the heart pericardium syndrome, fire toxin entering the meridians syndrome, heat entering the nutritive blood syndrome, and heat (fire) toxin accumulating in the skin syndrome. Mixed syndromes include: wind-heat, wind-fire, damp-heat, summer heat, warm dryness (dry heat), fire (heat) toxin, stasis heat, phlegm heat, and heat drink syndromes.
7) Toxin Syndrome: Refers to certain highly infectious special pathogenic factors, known as epidemic qi, also referred to as toxic qi or epidemic toxin. In the pathogenesis and syndrome names, the term “toxin” is often used, such as “toxic heat obstructing the lungs syndrome” or “epidemic toxin attacking the throat syndrome.” It also refers to certain toxic special pathogenic factors, often directly named with the term “toxin,” such as insect bites causing “insect toxin invading the skin syndrome,” wind toxin invading the meridians syndrome, fire toxin entering the meridians syndrome, or food poisoning causing “food toxin stagnating in the stomach syndrome.” It also refers to severe syndromes caused by excessive pathogenic factors, such as heat toxin, damp toxin, cold toxin, fire toxin, and phlegm toxin leading to various critical syndromes, such as heat toxin obstructing the lungs syndrome or toxin lurking in the membranes syndrome. Surgical conditions such as abscesses, carbuncles, and ulcers are often represented by the term “toxin,” such as heat toxin attacking the head and face syndrome, evil toxin flowing through the tendons syndrome, or pus toxin obstructing the skin syndrome.
8) Pus Syndrome: Refers to a pathological product formed by the stagnation of qi and blood due to fire heat and toxin, leading to the accumulation and fermentation of blood and flesh, resulting in a foul-smelling, thick liquid. Clinical manifestations are characterized by the accumulation of pus. Superficial abscesses, carbuncles, sores, and boils may present as soft, fluctuating lumps before rupture, with pus draining after rupture. Internal abscesses may present with cough and expectoration of purulent phlegm, vomiting of pus and blood, purulent urine, or purulent stools, often accompanied by fever, thick greasy tongue coating, and slippery rapid pulse. Common pus syndromes include: pus toxin accumulating in the skin syndrome, phlegm pus accumulating in the lungs syndrome, and pus accumulating in the intestines syndrome.
9) Food Accumulation Syndrome: Refers to symptoms caused by irregular eating habits, leading to stagnation of food in the stomach and intestines due to impaired digestion and absorption. Clinical manifestations include: abdominal distension, poor appetite, sour belching, vomiting of sour and spoiled food, foul-smelling stools, thick greasy tongue coating, and slippery strong pulse. Common syndromes include: food accumulation in the stomach and intestines syndrome and spleen deficiency with food accumulation syndrome.
10) Worm Accumulation Syndrome: Refers to symptoms caused by larvae invading the body or ingesting worm eggs that develop and reproduce within the body, leading to obstruction of the organs and consumption of qi and blood. Common syndromes include: intestinal worm accumulation syndrome, liver and gallbladder worm accumulation syndrome, intestinal obstruction due to worms, and gallbladder obstruction due to worms.
2. Qi Disease Differentiation:
1) Qi Deficiency Syndromes: Includes qi deficiency syndrome, qi sinking syndrome, qi not consolidating syndrome, and qi collapse syndrome.
1) Qi Deficiency Syndrome: Refers to insufficient original (true) qi, leading to reduced functions of promoting, warming, consolidating, defending, and transforming, or reduced functional activity of the organs and tissues. Causes include:
① Prolonged illness, severe illness, or excessive fatigue leading to depletion of original qi.
② Congenital deficiency or dietary imbalance leading to insufficient generation of original qi.
③ Aging and weakness leading to decline in organ function and depletion of original qi.
Clinical manifestations include: shortness of breath, low voice, shallow breathing, fatigue, dizziness, spontaneous sweating, worsening of symptoms after exertion, pale tongue, and weak pulse.
Common syndromes include: heart qi deficiency syndrome, lung qi deficiency syndrome, stomach qi deficiency syndrome, spleen qi deficiency syndrome, liver and gallbladder qi deficiency syndrome, kidney qi deficiency syndrome, heart-lung qi deficiency syndrome, spleen-lung qi deficiency syndrome, spleen-stomach qi deficiency syndrome, and lung-kidney qi deficiency syndrome. Mixed syndromes include: qi and blood deficiency, qi and yin deficiency, yang qi deficiency, and fluid deficiency syndrome.
2) Qi Sinking Syndrome: Refers to the inability of qi to rise, leading to the sinking of the clear yang qi and the inability to maintain the position of the internal organs. Causes: Generally develops from qi deficiency or is a special manifestation of qi deficiency.
Clinical manifestations include: dizziness, tinnitus, fatigue, shortness of breath, a feeling of qi sinking, or internal organ prolapse, or symptoms such as rectal prolapse or uterine prolapse.
Common syndromes include: middle qi sinking syndrome or spleen qi sinking syndrome, characterized by the prolapse of internal organs.
3) Qi Not Consolidating Syndrome: Refers to a condition where qi deficiency leads to a failure of consolidating functions. Causes: Generally develops from qi deficiency.
Clinical manifestations include: spontaneous sweating, susceptibility to colds, or various bleeding symptoms, or incontinence of urine and feces, nocturnal emissions, miscarriage, etc., accompanied by symptoms of qi deficiency such as shortness of breath, low voice, fatigue, etc.
Common syndromes include: defensive qi not consolidating (spleen-lung qi deficiency syndrome), qi not consolidating blood (spleen not governing blood syndrome), and lower source not consolidating (kidney qi not consolidating syndrome).
4) Qi Collapse Syndrome: Refers to a critical condition where original qi is severely deficient, leading to a near loss of consciousness. Causes: Generally develops from qi deficiency or qi not consolidating, or may be due to significant blood loss, termed “qi following blood loss.”
Clinical manifestations include: weak and irregular breathing, possible coma or fainting, continuous sweating, pale complexion, open mouth and closed eyes, limp limbs, incontinence, weak pulse, pale tongue, and white moist coating.
2. Qi Stagnation Syndromes: Includes qi stagnation syndrome, qi counterflow syndrome, and qi obstruction syndrome.
1) Qi Stagnation Syndrome: Refers to the stagnation of qi in a specific part of the body or a specific organ or meridian. Also known as qi depression syndrome or qi blockage syndrome. Causes include:
① Emotional distress, dietary imbalance, invasion of external pathogenic factors, or trauma.
② Pathological substances such as phlegm, blood stasis, food stagnation, parasites, or stones causing obstruction.
③ Weak yang qi or cold leading to stagnation of qi in the organs and meridians.
Clinical manifestations include: distension and pain in the chest, hypochondria, abdomen, etc., with symptoms varying in intensity, often relieved by belching, bowel sounds, or passing gas, and may worsen or improve with emotional changes.
Common syndromes include: liver qi stagnation syndrome, gastrointestinal qi stagnation syndrome, and liver-stomach qi stagnation syndrome. Mixed syndromes include: qi stagnation with blood stasis, qi depression transforming into heat, phlegm-qi blockage, qi stagnation with damp obstruction, and qi stagnation with water retention.
2) Qi Counterflow Syndrome: Refers to abnormal rising and falling of qi, leading to counterflow and disharmony. Causes include:
① External pathogenic factors or phlegm affecting the lungs.
② Cold, heat, water, food stagnation, or blood stasis affecting the stomach.
③ Emotional distress, anger, fear, etc., affecting the liver.
Clinical manifestations include: lung qi counterflow syndrome: cough and wheezing; stomach qi counterflow syndrome: belching, nausea, vomiting; liver qi counterflow syndrome: headache, dizziness, and qi rising from the lower abdomen to the chest and throat.
3) Qi Obstruction Syndrome: Refers to a condition caused by extreme anger, shock, or excessive worry leading to qi blockage, presenting with symptoms such as confusion or fainting, cold limbs, etc. Also known as spirit qi obstruction syndrome. Alternatively, it may be due to blood stasis, stones, parasites, or phlegm obstructing the vessels, presenting with severe pain at the obstruction site, possibly leading to fainting, urinary and bowel obstruction, coarse breathing, and strong pulse.
3. Blood Disease Differentiation:
1) Blood Deficiency Syndromes: Includes blood deficiency and blood loss.
1) Blood Deficiency Syndrome: Refers to insufficient blood volume, leading to an inability to nourish the organs, meridians, and tissues, presenting as weakness. Causes include:
① Excessive blood loss without timely replenishment.
② Impaired spleen and stomach function or insufficient nutrition leading to inadequate blood production.
③ Excessive worry and mental strain, or parasitic infections consuming nutrients, leading to blood loss.
④ Blood stasis obstructing the vessels, hindering blood production, or causing local blood supply insufficiency.
⑤ Prolonged illness or severe illness leading to depletion of essence and qi, exhausting the source of blood production.
Clinical manifestations include: pale or sallow complexion, pale lips, eyelids, and nails, dizziness, palpitations, numbness in the hands and feet, women with scanty pale menstrual flow, or amenorrhea, pale tongue, and thin weak pulse.
Common syndromes include: heart blood deficiency, liver blood deficiency, blood deficiency leading to intestinal dryness, and blood deficiency leading to skin dryness and wind syndrome. Mixed syndromes include: yin blood deficiency syndrome and blood deficiency with stasis syndrome.
2) Blood Loss: Refers to sudden and significant loss of blood due to vomiting blood, blood in stools, menorrhagia, or external trauma, leading to critical symptoms such as pale complexion, dizziness, palpitations, pale tongue, and weak or absent pulse, often accompanied by qi collapse and loss of yang, threatening life.
2. Blood Stasis Syndrome: Refers to symptoms caused by blood stasis. Blood stasis refers to blood that has not been expelled or dissipated in time, remaining in a certain area, or blood flow being obstructed, leading to stagnation and loss of physiological function. Causes include:
① Trauma or falls causing internal bleeding that has not been expelled or dissipated in time.
② Qi stagnation leading to poor blood flow, or qi deficiency leading to weak blood circulation.
③ Cold leading to blood stasis, or heat scorching blood, or damp-heat and phlegm-heat obstructing the vessels, leading to poor blood flow.
Clinical manifestations include:
① Pain: sharp and stabbing, fixed in one location, often worsening at night.
② Masses: visible as purple lumps on the skin, or hard lumps in the abdomen that do not move when pushed.
③ Bleeding: dark purple blood with clots, or black tarry stools. Women may experience amenorrhea, or menorrhagia.
④ Dark complexion, or cyanosis of the lips and nails, or subcutaneous purple spots, or visible veins on the abdomen, or red thread-like lines on the skin.
⑤ Purple or dark tongue, or visible purple spots, or engorged veins under the tongue, or blue-purple lines on the tongue edges.
⑥ Pulse is often thin and rough, or may be choppy, intermittent, or absent.
Common syndromes include: heart vessel obstruction syndrome, brain vessel obstruction syndrome, liver blood stasis syndrome, stasis in the uterus (or seminal chamber) syndrome, lower jiao blood stasis syndrome, and stasis in the skin syndrome. Mixed syndromes include: qi stagnation with blood stasis, blood stasis with qi stagnation, phlegm-stasis mutual blockage, stasis-heat mutual blockage, and blood stasis with water retention.
3. Blood Heat Syndrome: Refers to symptoms caused by excessive heat in the organs, leading to heat forcing blood into the blood division. Commonly seen in the most severe stages of exogenous warm diseases, referred to as “blood division syndrome.” Clinical manifestations include: coughing blood, vomiting blood, nosebleeds, blood in urine, blood in stools, excessive menstruation, menorrhagia, or abscesses and boils in the skin or internal organs, accompanied by irritability, thirst, fever, red tongue, and rapid pulse.
4. Blood Cold Syndrome: Refers to symptoms caused by cold pathogenic factors affecting the blood vessels, leading to obstruction of qi flow and poor blood circulation. Clinical manifestations include: cold pain in the hands and feet, dark purple skin, or cold pain in the lower abdomen, preference for warmth, relief from warmth, or menstrual irregularities with dark purple blood and clots, purple tongue, white coating, and deep slow pulse.
Common syndromes include: cold obstructing the liver meridian syndrome, cold obstructing the uterus syndrome, and cold obstructing the vessels syndrome.
4. Fluid Disease Differentiation:
1. Fluid Deficiency Syndrome: Refers to insufficient body fluids, leading to a lack of nourishment and hydration for the organs and tissues. Also known as fluid insufficiency syndrome. Fluid injury: refers to a mild loss of fluids, primarily due to water loss, also known as fluid deficiency. Fluid exhaustion: refers to a severe loss of fluids, where not only water is lost but also certain essential nutrients are damaged, also known as fluid depletion. Clinical manifestations are often referred to as fluid deficiency syndrome without strict differentiation.
Causes include:
(1) High fever, excessive sweating, vomiting, frequent urination, burns, etc., leading to excessive loss of fluids.
(2) Excessive yang leading to hidden consumption of fluids.
(3) Inadequate water intake, weak organ function, and insufficient generation of fluids.
Clinical manifestations include: dry mouth and throat, cracked or chapped lips, sunken eyes, dry skin, thirst for water, short and difficult urination, dry and hard stools, red tongue with little moisture, and thin or rapid pulse. Common syndromes include: lung dryness injuring fluids syndrome, stomach dryness fluid deficiency syndrome, and intestinal dryness fluid deficiency syndrome. Mixed syndromes include: dry fluids with blood deficiency, fluid deficiency with blood stasis, qi following fluid loss, and fluid and qi deficiency syndrome.
2. Phlegm Syndrome: Refers to pathological products formed by the accumulation of water and fluids, characterized by thick and sticky consistency, low fluidity, and easy obstruction in the organs and tissues. Clinical manifestations include: cough with phlegm, thick and sticky phlegm, chest tightness, nausea, vomiting of phlegm, dizziness, obesity, or mental confusion with phlegm sounds in the throat, or mental disorders such as mania, insanity, or epilepsy, or soft and smooth lumps in certain areas, such as goiter, lymphadenopathy, breast lumps, or globus sensation. Tongue coating is often greasy, and pulse is slippery. Common syndromes include: phlegm obstructing the heart spirit, phlegm heat obstructing the spirit, phlegm fire disturbing the spirit, phlegm obstructing the heart vessels, phlegm obstructing the chest yang, phlegm turbid obstructing the lungs, phlegm heat obstructing the lungs, phlegm heat obstructing the intestines, dry phlegm obstructing the lungs, phlegm turbid affecting the head, phlegm obstructing the uterus (or seminal chamber), phlegm dampness accumulation, phlegm obstructing the meridians, phlegm dampness condensing in the skin, wind phlegm obstructing the spirit, wind phlegm obstructing the vessels, phlegm stasis obstructing the vessels, phlegm qi stagnation, and purulent phlegm accumulating in the lungs.
Mixed syndromes include: cold phlegm, heat phlegm, damp phlegm, dry phlegm, wind phlegm, phlegm stasis, and purulent phlegm.
3. Fluid Accumulation Syndrome: Refers to symptoms caused by the accumulation of fluids in the stomach, lungs, chest, and abdomen due to the obstruction of the organs. Clinical manifestations include: dizziness, pale tongue, white slippery coating, and wiry pulse. Common syndromes include: cold fluid obstructing the lungs syndrome, fluid obstructing the heart pericardium syndrome, fluid obstructing the chest and abdomen syndrome, and fluid retention in the stomach and intestines syndrome.
4. Water Retention Syndrome: Refers to symptoms caused by dysfunction of the lungs, spleen, and kidneys, leading to the accumulation of fluids in the skin or in the chest and abdomen, which may fluctuate with body position. Causes include:
(1) External wind invasion, leading to lung dysfunction and obstruction of the water pathways.
(2) Internal dampness invasion, leading to spleen dysfunction and obstruction of fluid distribution.
(3) Internal injury from overwork, irregular sexual activity, prolonged illness, or excessive use of purgatives, leading to spleen and kidney yang deficiency, which cannot warm and transform fluids, resulting in fluid overflow.
(4) Blood stasis, stones, or other obstructions affecting the normal flow of fluids, leading to accumulation in the chest and abdomen. Clinical manifestations include: edema, which may occur in the lower limbs, face, or even the entire body, with pitting edema; or fluid accumulation in the chest and abdomen, presenting as chest tightness and abdominal fullness, with a dull sound upon percussion; and may fluctuate with body position, accompanied by short and difficult urination, slippery tongue coating, and soft pulse.
Common syndromes include: wind-water interaction syndrome, spleen deficiency with fluid overflow syndrome, kidney deficiency with fluid overflow syndrome, and water qi obstructing the heart syndrome.
1. Relationship Between Qi Collapse and Loss of Yang: Qi collapse and loss of yang often occur simultaneously, with similar clinical manifestations. The main feature of loss of yang is cold limbs and body, while the main feature of qi collapse is weak and near-extinct breath, often referred to as yang qi deficiency.
2. Differentiating Edema: Water is a tangible evil that overflows the skin, leading to facial and body swelling. Edema can be classified into two major categories based on the nature of the disease: 1) Yang Edema: The nature of the disease is excess. The onset is sudden, starting from the eyelids and face, rapidly spreading to the entire body, with thin and shiny skin, and more swelling in the upper body. Often accompanied by symptoms of wind invasion affecting the lung’s defensive qi. 2) Yin Edema: The nature of the disease is deficiency. The onset is gradual, starting from the feet and gradually spreading to the entire body, with unchanged skin color, and more swelling in the lower body. Often accompanied by symptoms of spleen and kidney yang deficiency.
3. Differentiating Bleeding:
Bleeding Differentiation Table

Summary:
1. Etiological Diagnosis:
1) Concepts and key points for differentiating the six excesses: wind, cold, summer heat, dampness, dryness, and fire. 2) The meaning of toxins and key points for differentiating pus syndrome, food accumulation, and worm accumulation syndromes.
2. Qi and Blood Differentiation:
1) Qi Disease Differentiation: Qi deficiency syndrome, qi sinking syndrome, qi stagnation syndrome, qi counterflow syndrome. 2) Blood Disease Differentiation: Blood deficiency syndrome, blood stasis syndrome, blood heat syndrome, blood cold syndrome.
3. Fluid Disease Differentiation: Fluid deficiency syndrome, water retention syndrome, phlegm syndrome, and fluid syndrome.

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