Six Stages (Shang Han)
A diagnostic framework from the Shang Han Lun (Treatise on Cold Damage) that categorizes externally contracted diseases into six stages based on how deeply a pathogen has penetrated the body, guiding treatment strategy at each level.
Liù Jīng Biàn Zhèng
Six Stages Pattern Differentiation
Educational content · Consult qualified TCM practitioners for diagnosis and treatment
Overview
The Six Stages framework is one of TCM's most important diagnostic systems for understanding how illness progresses through the body. Think of it like a map showing how a cold or flu can start as mild symptoms (chills, fever) and, if untreated, penetrate deeper to affect your internal organs more seriously.
The system divides disease progression into three Yang stages (representing the body's outer, more superficial layers and stronger immune response) and three Yin stages (representing deeper, internal layers where the body's defenses are weaker). When a pathogen first attacks, it typically hits the outermost Yang layer (Tai Yang). If the body can't fight it off, the disease moves inward through progressively deeper stages, potentially becoming more serious.
This framework helps practitioners determine exactly where a disease is located and how strong the patient's resistance is—information that directly determines which treatment approach will be most effective. A treatment that works for an early-stage illness could actually harm someone with a deep-stage illness, making accurate stage identification crucial.
Historical Context
The Six Stages system was created by Zhang Zhongjing (张仲景, approximately 150-219 AD), often called the "Medical Sage" of Chinese medicine. He developed this framework during a devastating period at the end of the Eastern Han Dynasty, when wars and epidemics killed many of his own family members. His compassion for suffering people drove him to systematically document how febrile diseases progress and how to treat them at each stage.
Zhang recorded his findings in the Shang Han Za Bing Lun (Treatise on Cold Damage and Miscellaneous Diseases), which was later divided into two texts: the Shang Han Lun (focusing on externally contracted diseases) and the Jin Gui Yao Lue (focusing on internal conditions). The theoretical foundation draws from earlier concepts in the Huang Di Nei Jing (Yellow Emperor's Classic), particularly the chapter on febrile diseases in the Su Wen.
The Song Dynasty edition (1065 AD) established the version most commonly used today. Over centuries, scholars have debated whether the Six Stages should be interpreted purely as a disease-progression model or connected more literally to the body's meridian system—a discussion that continues in modern TCM education.
Comparison
Tai Yang Stage
太阳病Location: Exterior/Surface | Nature: Yang (strong defense) | Key symptoms: Fever, chills, headache, stiff neck, floating pulse | Treatment principle: Release the exterior through sweating | Representative formula: Ma Huang Tang or Gui Zhi Tang
Yang Ming Stage
阳明病Location: Interior | Nature: Yang excess/Heat | Key symptoms: High fever, no chills, profuse sweating, thirst, constipation | Treatment principle: Clear interior heat, purge if necessary | Representative formula: Bai Hu Tang or Da Cheng Qi Tang
Shao Yang Stage
少阳病Location: Half-exterior, half-interior | Nature: Yang (pivotal) | Key symptoms: Alternating chills and fever, bitter taste, rib-side pain | Treatment principle: Harmonize and mediate | Representative formula: Xiao Chai Hu Tang
Tai Yin Stage
太阴病Location: Interior | Nature: Yin (cold/deficiency) | Key symptoms: Abdominal fullness, vomiting, diarrhea, no thirst | Treatment principle: Warm the middle, strengthen Spleen | Representative formula: Li Zhong Wan
Shao Yin Stage
少阴病Location: Interior (deep) | Nature: Yin (severe deficiency) | Key symptoms: Extreme fatigue, desire to sleep, cold limbs, weak pulse | Treatment principle: Rescue Yang, warm and tonify | Representative formula: Si Ni Tang or Huang Lian E Jiao Tang
Jue Yin Stage
厥阴病Location: Deepest interior | Nature: Yin-Yang collapse | Key symptoms: Cold extremities, thirst, mixed hot-cold signs, potential collapse | Treatment principle: Harmonize Yin-Yang, rescue collapse | Representative formula: Wu Mei Wan
Tai Yang (Greater Yang)
太阳The outermost defensive layer—your body's first line of defense. When illness first strikes, it hits here. Symptoms include fever with chills, headache, stiff neck, body aches, and a floating pulse. The pathogen hasn't penetrated deeply yet, so treatment focuses on releasing the exterior (helping the body push the pathogen out through sweating). Associated with the Bladder and Small Intestine meridians.
Yang Ming (Bright Yang)
阳明If the pathogen penetrates deeper or transforms into heat, it reaches Yang Ming—the body's interior with strong heat. This stage features high fever without chills, intense thirst, profuse sweating, constipation, and a dry yellow tongue coating. The body and pathogen are both strong here, creating intense heat. Treatment focuses on clearing internal heat and, if needed, purging the bowels. Associated with the Stomach and Large Intestine.
Shao Yang (Lesser Yang)
少阳A pivotal "half-exterior, half-interior" stage where the pathogen is caught between the surface and the depths. The hallmark symptom is alternating chills and fever (feeling cold, then hot, then cold again). Other signs include bitter taste, dry throat, rib-side discomfort, and loss of appetite. Treatment must "harmonize" rather than strongly sweat or purge—using the wrong method here can worsen the condition. Associated with the Gallbladder and San Jiao (Triple Burner).
Tai Yin (Greater Yin)
太阴The first of the Yin stages, indicating the pathogen has entered the body's interior and the patient's defensive energy is weakening. Characterized by cold signs: abdominal fullness, vomiting, diarrhea, lack of thirst, and a weak pulse. The digestive system (Spleen/Stomach function) is particularly affected. Treatment warms the interior and supports digestive function rather than attacking the pathogen directly.
Shao Yin (Lesser Yin)
少阴A serious stage affecting the Heart and Kidney—the body's fundamental vitality. The patient shows extreme fatigue, desire to sleep constantly, and cold limbs. Can manifest as either a cold pattern (requiring warming treatment) or a heat pattern (requiring nourishing treatment). This stage indicates the body's core energy is depleted and requires careful, supportive treatment.
Jue Yin (Terminal Yin)
厥阴The deepest stage, often representing the most critical condition where Yin and Yang are severely imbalanced. Symptoms can include cold extremities, intense thirst, chest heat with cold limbs, and potentially collapse. Paradoxically, this stage can show mixed heat and cold signs simultaneously. Associated with the Liver and Pericardium. Treatment aims to restore the balance between Yin and Yang and rescue collapsing conditions.
Practical Application
Determining the Stage: When evaluating a patient with an externally contracted illness (like a cold, flu, or infection), the practitioner assesses: Is there still fever with chills (exterior involvement)? Has the fever become constant and intense (interior heat)? Are symptoms alternating (half-and-half stage)? Is there cold with weakness (Yin stages)?
Treatment Selection: Each stage has specific treatment principles. At Tai Yang, you help the body expel the pathogen through sweating methods. At Yang Ming, you clear heat and potentially purge. At Shao Yang, you must harmonize—never use strong sweating or purging, as this can drive the pathogen deeper. At the Yin stages, you support the body's energy rather than attack the pathogen directly.
Tracking Progression: The framework also helps track whether treatment is working. If a patient moves from a Yin stage back toward Yang stages, it indicates recovery (the body's defenses are strengthening). Movement from Yang to Yin stages suggests deterioration requiring treatment adjustment.
Clinical Relevance
The Six Stages system remains highly relevant for treating modern infectious diseases, upper respiratory infections, and febrile conditions. Many practitioners use it for conditions like influenza, COVID-19, and other viral illnesses where tracking disease progression guides treatment timing and method selection.
Clinically, the system's greatest value is preventing mistreatment. Using a strong purging formula on a patient in Tai Yin stage (who needs warming and support) could seriously worsen their condition. Similarly, using warming herbs on someone in Yang Ming stage (with interior heat) would fuel the fire. The Six Stages system provides clear guidelines for matching treatment to disease location and patient constitution.
The framework also integrates with Eight Principle differentiation (Ba Gang), helping clarify whether a condition is exterior/interior, hot/cold, excess/deficient, and Yin/Yang—all crucial for treatment selection.
Common Misconceptions
"The stages always progress in order": Disease doesn't always move neatly from Tai Yang through each successive stage. It can skip stages (越经传, yuè jīng chuán), jump between them, or even directly attack a Yin stage in someone with weak constitution (直中, zhí zhōng). The framework describes possible patterns, not a rigid sequence.
"Six Stages is only for colds and flu": While originally developed for externally contracted febrile diseases, modern practitioners apply Six Stages thinking to internal diseases, chronic conditions, and even cancer treatment. The principles of tracking disease location and matching treatment to the body's state apply broadly.
"The Six Stages are the same as the Six Meridians": There's ongoing scholarly debate about whether the Six Stages correspond directly to the body's meridian system or represent a separate disease-classification scheme. While connections exist (Tai Yang relates to Bladder/Small Intestine meridians), the stages describe disease states rather than simply meridian pathology.
"Yin stages are always worse than Yang stages": Not necessarily. While Yin stages often indicate weakened defense, the Yang Ming stage with severe interior heat can be quite dangerous. The critical factor is whether the body's vital energy can still fight the pathogen effectively.
Classical Sources
Shang Han Lun (伤寒论)
Tai Yang Chapter, Line 1太阳之为病，脉浮，头项强痛而恶寒
In Tai Yang disease, the pulse is floating, there is headache and stiff neck with aversion to cold
Shang Han Lun (伤寒论)
Yang Ming Chapter, Line 180阳明之为病，胃家实是也
In Yang Ming disease, there is repletion in the stomach domain
Shang Han Lun (伤寒论)
Shao Yang Chapter, Line 263少阳之为病，口苦，咽干，目眩也
In Shao Yang disease, there is bitter taste in the mouth, dry throat, and dizziness
Huang Di Nei Jing Su Wen (黄帝内经素问)
Chapter 31 - Re Lun (On Heat)热病者，皆伤寒之类也
Heat diseases are all of the cold damage type - establishing the theoretical foundation for Six Stages
Modern References
Discussion of Cold Damage (Shang Han Lun): Commentaries and Clinical Applications
Comprehensive English translation with clinical commentary on applying Six Stages in modern practice
Shang Han Lun: On Cold Damage, Translation and Commentaries
Scholarly translation preserving classical terminology with extensive notes
The Shang Han Lun for the Modern Clinician
Practical guide for applying Six Stages theory to contemporary clinical conditions