The 8 Principles framework helps you rapidly define:
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Nature of the imbalance (Cold/Heat, Xu/Shi)
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Depth of pathology (Exterior vs Interior)
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Urgency and direction of treatment
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Use of tonification vs dispersion, moxa vs bleeding
Once the Ba Gang pattern is established, you can integrate with other systems (Zang-Fu, 6 Levels, 5 Elements, etc.) to refine diagnosis and point selection.


Cold - Hot Patterns

Exterior Cold
(Wind-Cold Invasion)
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SP Yang Deficiency: Cold limbs, diarrhea, abdominal bloating, fatigue
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KI Yang Deficiency: Cold knees/back, oedema, low libido, weak urination
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Cold in the Stomach: Epigastric pain relieved by warmth, no thirst
Treatment Principle
Warm the Interior, tonify Yang, dispel Cold
Interior Cold
-
SP Yang Deficiency: Cold limbs, diarrhea, abdominal bloating, fatigue
-
KI Yang Deficiency: Cold knees/back, oedema, low libido, weak urination
-
Cold in the Stomach: Epigastric pain relieved by warmth, no thirst
Treatment Principle
Warm the Interior, tonify Yang, dispel Cold
Exterior Heat
(Wind-Heat Invasion)
Fever > chills, Sore throat, thirst, Slight sweating, Yellow nasal discharge, Floating-rapid pulse, Red tip of tongue, thin yellow coat
Treatment Principle
Release Exterior, clear Heat
Interior Heat
High fever, thirst, constipation, dark urine, Red face, irritability, Red tongue, thick yellow coat
Full-rapid pulse

Cold (寒 Hán)
Yin
Slowing, constricting
Gradual (can also be acute)
Aversion to cold, cold limbs, pale face
Slow, deep, tight
Pale, moist, white coat
Excess Heat or Yin Deficiency (Empty Heat)
Heat (热 Rè)
Yang
Accelerating, rising, expanding
Often rapid onset
Fever, thirst, restlessness, red face
Rapid, full, superficial or wiry
Red body, yellow coat
Excess Heat or Yin Deficiency (Empty Heat)
Yin and Yang are the fundamental lens through which we determine the nature of any pathological condition in TCM. All other principles (Cold/Heat, Interior/Exterior, etc.) are manifestations of Yin-Yang dynamics. Correct diagnosis and treatment require understanding which side is dominant, which is deficient, and how to rebalance the two. It is important to use Yin-Yang to quickly determine is it acute (Yang) or chronic (Yin)? is there excess or deficiency? do you need to tonify (usually Yin) or disperse (often Yang)? Or should you use moxa (to warm Yang) or bleeding (to drain Fire/Heat/Yang)?

Yin/Yang Examples in Clinical Patterns

Liver Yin Deficiency with Empty Heat
Yin Deficiency pattern
Symptoms
Dry eyes, irritability, night sweats, red tongue with little coat
Nature
Yin deficiency → false Yang rising
Treatment
Nourish Liver Yin, clear Empty Heat
Points
LR8, KI3, SP6, PC6, Yin Tang

Kidney Yang Deficiency
Yang Deficiency pattern
Symptoms
Cold limbs, lower back pain, clear urination, fatigue, low libido
Nature
Deficient Yang (Cold, Interior, Deficiency → all Yin features)
Treatment
Warm and tonify Kidney Yang
Points
DU4 (Mingmen), BL23, Ren4 (moxa), KI3, ST36

External Wind-Heat Invasion
Yang pattern: acute onset, superficial level
Symptoms
Fever, sore throat, thirst, floating rapid pulse
Treatment
Release the Exterior, clear Heat
Points
LU7, LI4, LI11, DU14
3. Has the Yin-Yang balance been lost?

Collapse of Yin
Sudden profuse sweating, thirst, dry mouth, rapid pulse

Collapse of Yang
Cold sweat, loss of consciousness, minute pulse, cold extremities
2. Is Yin or Yang in excess or deficiency?
01
Yin Deficiency
Internal Heat, night sweats, dry mouth, red tongue, thin rapid pulse
02
Yang Deficiency
Cold limbs, fatigue, pale swollen tongue, slow deep pulse
03
Excess Yin (Cold Excess)
Cold, stagnation, abdominal pain, tight pulse
04
Excess Yin (Cold Excess)
Cold, stagnation, abdominal pain, tight pulse

1. Is it Yin or Yang in nature?
Yin (阴)
Cold
Interior
Deficiency
Chronic
Pale
Slow
Stillness’
Dampness
Stagnation
Weakness
Cold limbs
Pale complexion
Preference for warmth
Weak pulse
Yang (阳)
Heat
Exterior
Excess
Acute
Red
Rapid
Movement
Dryness
Activity
Agitation
Fever
Red face
Restlessness, thirst
Strong pulse

Nature
Yin-Yang
Yin and Yang are foundational concepts that describe the essential nature of any condition. The other 6 principles (Interior/Exterior, Cold/Heat, Deficiency/Excess) all derive from and reflect the dynamic of Yin and Yang. Yin and Yang represent the two opposing yet complementary forces in nature — they are in constant dynamic balance. Every pattern in TCM can be understood through the lens of Yin-Yang polarity. Thus, Yin and Yang define the depth of the disease (surface vs. core), the temperature and activity level, the energetic dynamic (weakness vs. repletion) and the direction of treatment (tonify Yin, sedate Yang, etc.).

What is the 8 Principles?
The 8 Principles (Ba Gang 八纲) are the most fundamental diagnostic framework in Traditional Chinese Medicine (TCM). They provide a structured approach to understanding the nature, location, and strength of any given pathology. These principles allow practitioners to classify syndromes and guide treatment strategy with precision.
Nature
Yin vs Yang: Describes the overall energetic quality
Location
Interior (Li) vs Exterior (Biao): Localizes the disease – superficial or deep
Temperature
Cold (Han) vs Heat (Re): Identifies the thermal nature of the pattern
Strength
Deficiency (Xu) vs Excess (Shi): Determines whether there is weakness or surplus

8 Principles

Location
Exterior / Interior
The Interior vs. Exterior (Li vs. Biao / 里 vs. 表) is one of the 8 Diagnostic Principles (Ba Gang 八纲) and is used to determine the location of a pathological condition. It helps the practitioner know how deep a disease process has penetrated the body and what structures or systems are involved. This greatly influences treatment strategy, such as whether to release the exterior, tonify internal organs, or harmonize half-exterior/half-interior layers.
Exterior Patterns are usually caused by external pathogenic factors invading the body, particularly Wind, often combined with Cold or Heat. These affect the superficial layer (Wei Qi) and cause symptoms at the skin and muscle level. Key symptoms include fever and chills (simultaneous), aversion to wind or cold, occipital headache, body aches, sneezing, nasal congestion, thin white tongue coat and a floating pulse. Examples include Invasion of Wind-Cold → chills > fever, no sweating, tight floating pulse and Invasion of Wind-Heat → fever > chills, sore throat, thirst, floating rapid pulse
Interior Patterns affect the internal organs (Zang-Fu) and their functional systems. These patterns are often due to improper diet, emotional stress, overwork, internal Cold or Heat and unresolved exterior conditions that have penetrated inward. Key symptoms include organ-based signs (e.g., cough, nausea, abdominal pain, diarrhea, urinary symptoms), absence of aversion to wind/cold, deeper pathology with potential deficiency or excess, tongue shows body or coat changes, and pulse is deep. Examples include Liver Qi Stagnation → irritability, hypochondriac pain, Spleen Qi Deficiency → fatigue, loose stools, poor appetite and Kidney Yang Deficiency → cold limbs, low libido, lower back pain.
Understanding whether a condition is Exterior or Interior helps choose the right treatment principle, select appropriate point categories (surface vs. deep), time the use of moxa or herbs (e.g., avoid tonification too early in an Exterior condition) and monitor disease progression (e.g., if an Exterior syndrome goes untreated, it can penetrate to the Interior)
Exterior (表)
Skin, muscles, Wei Qi, superficial meridians
External pathogenic factors (Wind, Cold, Heat)
Sudden, acute
Chills/fever, headache, body aches, aversion to cold, floating pulse
Usually normal body, thin white coat
Floating
Release the Exterior, expel the pathogen, support Wei Qi.
LU7, LI4, BL12, GB20, DU16
Use dispersion techniques, sometimes moxa (Wind-Cold), or cooling herbs (Wind-Heat)
Interior Patterns affect the internal organs (Zang-Fu) and their functional systems. These patterns are often due to improper diet, emotional stress, overwork, internal Cold or Heat and unresolved exterior conditions that have penetrated inward. Key symptoms include organ-based signs (e.g., cough, nausea, abdominal pain, diarrhea, urinary symptoms), absence of aversion to wind/cold, deeper pathology with potential deficiency or excess, tongue shows body or coat changes, and pulse is deep. Examples include Liver Qi Stagnation → irritability, hypochondriac pain, Spleen Qi Deficiency → fatigue, loose stools, poor appetite and Kidney Yang Deficiency → cold limbs, low libido, lower back pain.
Interior (里)
Zang-Fu organs, deeper structures
Internal dysfunction (diet, emotions, lifestyle)
Gradual, chronic
Organ-related signs (cough, vomiting, diarrhea, etc.)
Changes in body colour, coat thickness or moisture
Floating
Regulate or tonify internal organs, clear internal Heat/Cold, move Qi or Blood, resolve Dampness or Phlegm.
ST36, SP6, LR3, BL20, KI3 depending on organ and pattern
Interior Patterns affect the internal organs (Zang-Fu) and their functional systems. These patterns are often due to improper diet, emotional stress, overwork, internal Cold or Heat and unresolved exterior conditions that have penetrated inward. Key symptoms include organ-based signs (e.g., cough, nausea, abdominal pain, diarrhea, urinary symptoms), absence of aversion to wind/cold, deeper pathology with potential deficiency or excess, tongue shows body or coat changes, and pulse is deep. Examples include Liver Qi Stagnation → irritability, hypochondriac pain, Spleen Qi Deficiency → fatigue, loose stools, poor appetite and Kidney Yang Deficiency → cold limbs, low libido, lower back pain.

Temperature
Heat / Cold
The Cold vs. Heat principle (寒 / 热, Hán / Rè) is one of the Eight Diagnostic Principles (Ba Gang 八纲), and it reflects the thermal nature and the energetic activity of a disorder. This distinction helps determine whether the body’s functional state is in a hypoactive (Cold) or hyperactive (Heat) condition, and it plays a critical role in the selection of points, techniques, and formulas.

Strength
Deficiency / Excess
The principle of Deficiency vs. Excess (Xu vs. Shi / 虚 vs. 实) is crucial to understanding the strength of the body’s Zheng Qi (Upright Qi 正气) in relation to the pathogenic factor (Xie Qi 邪气). It reveals whether the condition arises from internal weakness or external/internal excess and directly determines the treatment principle — whether to tonify or drain.

Deficiency (虚 Xu)
Weak
May be absent or present in small amount
Hypoactivity, lack of force
Gradual, chronic
Weak, empty, thin
Pale, thin, little coat (or no coat in Yin Xu)
Fatigue, spontaneous sweating, shortness of breath, weak voice
Tonify the body's Qi, Blood, Yin or Yang
Deficiency patterns result from insufficiency of vital substances Qi Deficiency, Blood Deficiency, Yin Deficiency or Yang Deficiency
Fatigue, low voice, dizziness, pale face, spontaneous sweating, night sweats, weak pulse
Spleen qi deficiency, heart blood deficiency, kidney yin deficiency
Tonification (reinforcing), moxibustion often used in Yang Xu
Weak pulse, pale tongue
Weak, quiet voice, cold limbs, fatigue
Weak, forceless pulse → Tonify
Excess (实 Shi)
Strong or adequate
Present and overwhelming
Hyperactivity, stagnation, repletion
Sudden, acute
Full, strong, wiry, slippery
Red, thick yellow coat (in Heat Excess)
Strong symptoms, tension, pain, heat or cold
Tonify the body's Qi, Blood, Yin or Yang
Excess patterns arise from an overabundance of a pathogenic factor or obstruction due to External pathogens (Wind, Cold, Damp, Heat), Stagnation of Qi or Blood or Accumulation of Phlegm, Dampness, or Food
Forceful symptoms, restlessness, strong pain, constipation, thick tongue coat, full pulse
Liver qi stagnation, damp-heat in the lower jiao, phlegm-heat in the lungs, blood stasis
Dispersing (reducing), may use bleeding, cupping, gua sha, or no moxa in Heat Excess
Full pulse, thick coat
Loud voice, restlessness, strong pain
Full, resisting pulse → Disperse