中医的八纲辨证其虚实是中医治病的根据的一个基础。
虚，指正气虚。 实，指邪气实。也讲，“正气在内，邪不可侵”
在生活中我们可以理解成如果生命体的正气充沛，五脏生克调节有度则不容易生病（收到外邪的侵害）。即西医讲的“免疫力强，体质佳“。 在我们中医学有扶正的概念，即扶植正气；当一个生命体病久体虚的时候，不光有外邪还有可能出现自身正气过渡消耗之证，为虚证。即由此得来，急多实证，久多虚证。
中医治病在于求本，培植正气。西医治病侧重在”除实“针对实证（病症）下手。例如有炎症的消炎，有病毒则杀病毒。哪怕药物也对自身有影响。中医扶正气的治疗方法多是改变其实证之所以形成存在的生存条件与环境。并加以扶持正气让病患自己恢复自愈。此是中医病机与治疗原则。
【素问.通评虚实论】中写道“邪气盛则实，精气夺则虚“。其实虚与实证即可独立存在又可以同时存在或是互相转换。
张景岳说”邪气盛则实，精气夺则虚，此虚实之大法也。设有人焉，正巳夺而邪方盛者，将顾其虚而补之乎？抑先其邪而攻之乎？见有不的，则死生系之，此其所以宜慎也。扶正者本也，邪者标也。若正气既虚，则邪气最盛，亦不可攻，盖恐邪去未去而正气先脱，呼吸变生，则措手不及。故治虚邪者，当先顾其正气，正气存而不致于害。思补中自有攻意，盖补阴即所以攻热，补阳即所以攻寒，世未有正气复而邪不退者，亦未有正气竭而命不倾者。如必不得已，亦当酌量缓急，暂从权宜，从多从少，愈战于受斯可矣，此治虚之道也。若正气无损者，邪气虽微，自不宜补，盖补之则正气无与，反而邪盛，适足以借寇兵而资盗粮。故治实证者，当直攻其邪，邪去则身安。但法贵精专，便臻速效，此治实之道。 要之，能胜攻者，方是实证。实者可攻，何虑之有？不能胜攻者，便是虚证，气去不返，何不寒心？此邪正之本末，不可不知也“
总结阴阳虚实内外寒热的病理，阳虚则外寒，阴虚则内热。阳盛侧外热，阴盛则内寒-【素问.调经论】
看老年与肿瘤宠物有感后笔于甲辰年
Eight Principles of Syndrome Differentiation in TCM: Xu (Deficiency) and Shi (Excess)
In Traditional Chinese Medicine (TCM), the differentiation of deficiency (Xu) and excess (Shi) serves as a fundamental basis for diagnosing and treating diseases.
- Xu (Deficiency): Refers to the insufficiency of Zheng Qi (vital energy).
- Shi (Excess): Refers to the presence of excessive Xie Qi (pathogenic factors).
As the saying goes: "When Zheng Qi resides within, Xie Qi cannot invade."
Explanation of the Concept
This can be understood in everyday terms: when the body's Zheng Qi is abundant and the Five Zang Organs maintain a balanced cycle of promotion and inhibition, the body is less likely to fall ill or be invaded by external pathogens. This aligns with the Western medical idea of strong immunity and robust constitution.
TCM introduces the concept of Fuzheng, which emphasizes supporting and nourishing Zheng Qi. For example, when a body is weakened by prolonged illness, not only may external pathogenic factors invade, but the body’s own Zheng Qi may become excessively depleted, leading to deficiency syndromes. This is why it is said: acute illnesses are often excess syndromes, while chronic illnesses tend to result in deficiency syndromes.
Core Principles of TCM Treatment
The primary goal of TCM is to address the root cause (qiuben) of disease by cultivating Zheng Qi. In contrast, Western medicine tends to focus on "eliminating excess" by targeting the symptoms directly. For instance:
- Inflammation is treated with anti-inflammatory drugs.
- Viral infections are addressed by antiviral medications.
However, these treatments, while effective at addressing the pathogen, may also impact the body’s own health. TCM, on the other hand, aims to change the environment and conditions that allow the pathogenic factors to thrive, while simultaneously supporting Zheng Qi, enabling the body to heal itself. This embodies TCM's unique approach to pathology and treatment principles.
Classical Wisdom on Xu and Shi:
In Suwen: The Plain Questions – Treatise on Xu and Shi, it is written:
"When pathogenic Qi is abundant, there is excess. When essential Qi is depleted, there is deficiency."
Deficiency and excess syndromes can exist independently, coexist, or even transform into each other.
Zhang Jingyue’s Insight on Xu and Shi:
Zhang Jingyue provided a detailed explanation:
- “When pathogenic Qi is abundant, there is excess. When essential Qi is depleted, there is deficiency. This is the fundamental law of Xu and Shi.”
When treating a patient, a key dilemma arises:
- Should the focus be on replenishing the deficiency, or on expelling the excess?
- If misjudged, the outcome could determine life or death, and thus caution is paramount.
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Treatment of Deficiency (Xu):
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"Zheng Qi is fundamental; Xie Qi is secondary."
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If Zheng Qi is weak and Xie Qi is overwhelming, one must avoid aggressive expulsion of the pathogen, as this may further deplete Zheng Qi. For example, improper treatment might lead to a situation where the body loses vital energy faster than the pathogen is eliminated, resulting in critical harm.
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TCM adopts a strategy of nourishing Yin to counter heat and tonifying Yang to dispel cold. Supporting Zheng Qi helps ensure that the body can naturally eliminate pathogens. "When Zheng Qi is restored, Xie Qi will retreat on its own."
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However, when it becomes absolutely necessary to address both deficiency and excess, careful consideration must be given to the patient’s condition, weighing urgency, severity, and treatment intensity.
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Treatment of Excess (Shi):
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If Zheng Qi remains intact, even in the presence of mild pathogenic factors, excessive supplementation is discouraged. Over-supplementation may instead strengthen the pathogen ("lending weapons to the enemy").
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In cases of true excess, direct expulsion of the pathogen is appropriate. Once the pathogenic Qi is removed, the body naturally regains health. Precision and swift effectiveness are the keys to treating excess syndromes.
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The guiding principle is: "If the body can endure the treatment, it is an excess syndrome and can be resolved by expelling Xie Qi. If the body cannot endure, it is a deficiency syndrome, and further depletion would be harmful."
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Pathological Dynamics of Yin-Yang and Xu-Shi:
The relationship between Yin-Yang and Xu-Shi reveals the underlying mechanisms of many conditions:
- Yang Deficiency (Xu): Leads to external cold.
- Yin Deficiency (Xu): Results in internal heat.
- Yang Excess (Shi): Causes external heat.
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Yin Excess (Shi): Leads to internal cold.
(Suwen: Treatise on Regulation of the Five Circulations)