The layers of Xiao Chai Hu Tang

The formula Xiao Chai Hu Tang is the main formula in the treatment of Shao Yang disorders. It is widely used for a large range of disorders, but to properly utilize this formula and witness it’s incredible effects, it is essential to fully understand it’s underlying mechanism.

First of all, in order to realize this formula’s full scope of action, it is necessary to understand the Shao Yang conformation. The understanding of the Shao Yang conformation, stems from 2 main qualities that characterize it:

  1. The first quality is embedded in the name of the conformation – “the small yang” (少 shao = small)
  2. The second quality is manifested in the description of its location – “half exterior half interior”

1. The Small Yang

Among the 3 yang conformations, the yang of the Shao Yang is the weakest. This is not a pathological condition, but rather a description of the character and dynamics of this conformation.

It has a similar characteristic to the sun during sunrise, when the sun is weak in the sense that it is not warming and not blinding, but its appearance fills the world with a sense of excitement, vitality and anticipation towards the new day; light starts to dominate the sky and the awakening of the world fills it with motion.

This is exactly the driving force within our body, the force which is not intimidating or aggressive, but through vigor and excitement initiates action. This is an important motivating force behind every process in the body, and it has a widespread effect, both physical as well as emotional.

However, we must always remember, it is after all weak in the sense that is easily harmed, and is dependent on the support of a stronger and a more stable force. This support comes mainly from the Tai Yin conformation. The relationship of these two conformations is so essential, that it is already embedded into the formula Xiao Chai Hu Tang.

2. Half exterior, half interior

The Shao Yang conformation serves as a pivot that regulates between the external forces affecting the body, and the internal forces within the body.

Externally it effects the activity of the Tai Yang conformation, motivating the processes involved in guarding against the harmful effect of external pathogenic influences, while stimulating the sense of joy that stems from experiencing the abundance of the surrounding world.

Internally, it effects the activity of the Yang Ming conformation, motivating the processes of digestion, metabolism and excretion.

In addition to being a motivating and stimulating force, it also enables the communication and regulation between the external conditions and the internal needs; a communication which is at the core of proper body function.


The symptoms of a Shao Yang pathology are detailed in numerous lines in the Shang Han Lun, which demonstrates the wide range of effect a pathology of this conformation might have. The symptoms can be classified into two main groups. It is necessary that characteristics of both groups manifest in the clinical presentation, in order to diagnose a Shao Yang disorder. The 2 groups are:

Disorders of flow and movement

The Shao Yang is a pivot between the exterior and the interior of the body. This requires it to be able to regulate the movement required for communication and response.

Pathology in this aspect, can often manifest in symptoms that we relate to Qi stagnation or phlegm stagnation. The stagnation often manifests in areas of the body related to the Shao Yang, appearing in symptoms such as: one-sided headaches, sensation of fullness, pain or stuffiness in the chest and hypochondrium, pain or discomfort in the gallbladder organ.

Damage to the regulation of flow in the conformation can also result in a condition referred to as “wood attacking earth”. This can manifest as “gallbladder attacking Stomach” with symptoms of nausea, vomiting, epigastric discomfort or pain. In fact, nausea and epigastric discomfort are clinical manifestations, so closely associated with Shao Yang pathology, that they are addressed directly in the formula Xiao Chai Hu Tang. Symptoms of “liver attacking spleen” can also be attributed to the Shao Yang pathology, manifesting in symptoms such as abdominal discomfort and pain, irregular bowel movements and even gynecological disorders.

In addition to the physical manifestations, pathology in this conformation often manifests emotionally. The obstruction to the flow of Shao Yang leads to a state where the patient might feel overwhelmed by the requirements of daily life or does not sense the excitement and vitality that this conformation produces. This can appear as an emotional state of pessimism, inability to feel pleasure or excitement, lack of general interest in the different aspects of life, both physical and emotional. In very extreme cases this can even lead to depression to the degree of being suicidal.

Heat manifestations

The yang of this conformation is weak in the sense of intensity and strength, but it is full of vitality and motion. Therefore, in a pathogenic state, it easily develops into pathological heat, usually in the upper region of the body. Symptoms include redness and agitation in the eyes, dizziness, tinnitus, emotional restlessness and agitation, dryness in the throat, bitter taste in the mouth, fever (either alternating fever and chills, or persistent fever if the organ itself is involved).

Alternating fever and chills is a symptom which not only demonstrates the tendency towards heat, but also the dynamics of the battle of the Shao Yang conformation with a pathogenic factor. The heat presents the struggle against the pernicious influence, while the chills demonstrate the inability to persist in this struggle, resulting in intermittent retreats of the yang, leaving the body with a cold sensation. There are commentators, which see this to represent a general dynamics of Shao Yang pathology, which could manifest as symptoms appearing in recurring episodes, not necessarily involving fever (Huang Huang, Ten Key Formula Families in Chinese Medicine, p.77).

Harmonizing the Shao Yang

The treatment strategy is to “harmonize the Shao Yang”, a strategy which is impossible to grasp without fully understanding the different aspects of Xiao Chai Hu Tang.

The description of the formula is spread over several lines in the text, demonstrating the various presentations and considerations in using this formula. The herbs combining the formula are listed in line 96 of the text. In addition to the main herbs of the formula, there is also a list of changes that should be made to the formula in different clinical presentations. This is not considered to be a modification of Xiao Chai Hu Tang, but rather different variations of the same strategy of harmonizing the Shao Yang. This is also an indication to the diverse clinical presentations of Shao Yang disorders.

Ingredients and variations

This is a list of the main variation of Xiao Chai Hu Tang:

Chai hu 40g

Huang qin 15g

Ren shen 15g

Ban xia 15g

Sheng jiang 15g

Zhi gan cao 15g

Da zao 4 pieces

The analysis below will include explanation of the main herbs, as well as their variations.

Chai Hu

Acrid, bitter and slightly cold, with an upward and dispersing motion. In the Materia Medica it is grouped with herbs that release the exterior, and therefore can accordingly be viewed as a herb that benefits the connection between the Shao Yang and the external Tai Yang conformation.

In the Shang Han Lun the dose of this herb is 40g, compared to the other herbs in the formula which are 15g. This high relative dose should be kept when using Chai Hu to treat Shao Yang disorders.

Chai Hu is the only one herb of Xiao Chai Hu Tang which is never replaced in any of the variations that can manifest in a Shao Yang disorder.

Huang Qin

Cold and bitter, it clears heat from the liver and gallbladder organs, as well as from the upper part of the body, where the heat often manifests in a Shao Yang disorder. Being bitter and cold, it is a lowering herb that connects with the Yang Ming conformation.

These 2 herbs – Chai Hu and Huang Qin – combine to address the treatment strategy of “harmonizing the Shao Yang”:

  • Chai Hu connects from the inside upward and outward, while Huang Qin connects from the Upper Jiao toward the Middle Jiao. This combination serves to regulate the pivot function of the Shao Yang.
  • Chai Hu treats the external aspects related to the Shao Yang channel, Huang Qin treats the internal aspects related to the Shao Yang organ.
  • Chai Hu treats the tendency of Shao Yang pathology to create stagnation, while Huang Qin treats the tendency of Shao Yang pathology to create pathogenic heat.

Before I read the Shang Han Lun carefully, I was certain this combination was essential for treatment of Shao Yang, no matter the presentation. However, according to the variations listed in line 96, while Chai Hu is indeed essential, Huanq Qin should be replaced in certain cases:

The combination Chai Hu–Shao Yao

The combination of Chai Hu with Huang Qin is for upper body presentation – from the diaphragm, hypochondrium and epigastrium to the head. If the clinical presentation is in the abdominal area, the text instructs to remove Huang Qin, and add Shao Yao (Bai Shao or Chi Shao) instead. This creates the combination Chai Hu-Shao Yao, which we know as a common combination for liver Qi stagnation. It is important to emphasize that when treating a Shao Yang disorder, the relative dose should stay 2-3:1 in favor of Chai Hu.

The combination Chai Hu–Fu Ling

As mentioned before, the yang of the Shao Yang conformation is naturally “small” and vulnerable. In the event it has been pathologically weakened, the cold and bitter properties of Huang Qin might cause further harm. The text offers us the example of symptoms of palpitations and inhibited urination to demonstrate this situation. In the Shang Han Lun, the combination of these 2 symptoms is mentioned as an indication of damaged fluid circulation which obstructs the flow of Qi, causing palpitations. The treatment recommendations are addressed at supporting the Yang Qi, which is the force powering the fluid circulation.

In case of a Shao Yang presentation, accompanied with signs of obstruction to flow due to weakness, Fu Ling is combined with Chai Hu. Fu Ling is a diuretic herb which can restore the flow of fluid, but more importantly in this case, strengthens Spleen Qi, which supports the Shao Yang Qi, and calms the heart to revive the child-like spirit of Shao Yang.

I often use this combination in cases where there is an emotional state where the patient has the physical ability to make adjustments to improve his life, but has lost the vigor and ability to envision a better life. Common statements I hear from these patients are “what’s the use?”, “nothing matters anyway”, etc.

Sheng Jiang and Ban Xia

Warm and acrid, they warm the stomach and free the flow between the stomach and the lungs, treating symptoms on both sides of the diaphragm.

The combination of these 2 herbs is a formula in itself, called Xiao Ban Xia Tang. These two herbs have similar qualities while complementing each other through an external-internal perspective:

  • Sheng Jiang works on the external level of the body, often used to help release external pathogens
  • Ban Xia works on the internal level of the body, transforming phlegm and lowering rebellious Qi

Together they work to enhance the pivot function of the Shao Yang, regulating between the external and internal environments, freeing the flow due to Qi stagnation or phlegm obstruction, and harmonizing the organs in the diaphragm region, a muscle related to the Shao Yang, and directly treating nausea and vomiting, symptoms which often indicate Shao Yang pathology.

However, these herbs should be replaced in certain cases:

Ban Xia is a drying herb, and will therefore be replaced when there is thirst, or vexation in the chest without nausea or vomiting. Since Shao Yang pathology has a strong tendency towards phlegm obstruction, it is replaced with other herbs that transform phlegm, but do not dry or warm, namely Gua Lou Pi or Tian Hua Fen.

Sheng Jiang will be replaced by Gan Jiang in the event there is significant harm to the Yang Qi of the Shao Yang, causing obstruction in the chest of Qi and fluids. In this situation, the formula must regulate the flow and therefore in addition to Gan Jiang which warms the yang and induces movement, it is recommended to also remove Ren Shen and Da Zao, which are heavy herbs that might inhibit the flow, and add sour Wu Wei Zi, to complement the acridity of Gan Jiang and achieve the necessary regulation to the movement in the chest.

Ren Shen, Da Zao, Zhi Gan Cao

Sweet herbs that strengthen the Qi and the earth organs. As mentioned before, the Shao Yang Qi has the quality of a small child, which has essential benefits to the proper function of the body, but at the same time, requires support of a stronger and more stable force. This support comes from the Tai Yin conformation, which is addressed by these 3 herbs.

The text reminds us that while it is crucial to use these herbs to support the Shao Yang, they can impede the recovery of flow of the Shao Yang in certain situations:

  • When there is significant obstruction in the chest – remove Ren Shen and Da Zao, replace Sheng Jiang with Gan Jiang and add Wu Wei Zi
  • When there is an active external pathogenic influence – remove Ren Shen, and add a herb to release the exterior, the text recommend Gui Zhi
  • When the phlegm stagnation forms a palpable mass – remove Da Zao and add Mu Li to soften masses.

The main form of treatment in the Shang Han Lun is through the use of herbal formulas. These formulas serve not only as treatment recommendations, but also to demonstrate the underlying treatment principles required in the specific situation. These treatment principles are guidelines which can be applied to other treatment methods. The formula Xiao Chai Hu Tang is an amazing example of how understanding the intricacies of the recommended formula can increase our understanding of the pathology, and the mechanism of the required treatment strategy.

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