The Great Harmonizing Prescription: Xiao Chai Hu Tang

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Article originally published December 1, 2021. Xiao Chai Hu Tang

Harmonizing is one of the eight treatment methods used in traditional Chinese medicine. In both the Shang Han Lun and Jin Gui Yao Lue, Zhang Zhong Jing was the first physician to utilize the term "harmonious" (和 hé) in describing the action of herbal formulas, in this case specifically referring to Xiao Cheng Qi Tang and Gui Zhi Tang. Later, in Discussion Illuminating the Principles of Cold Damage written in 1156, Cheng Wu-Ji applied the concept of harmonization specifically to the treatment of Shao Yang disorders:

"When there is a cold damage pathogen in the exterior, one must seep it from the body as sweat. When the pathogen is located in the interior, one must flush and scour it out as diarrhea. When it is neither in the exterior nor the interior but half outside and half inside, inducing sweating is not appropriate, nor do vomiting or purgation provide an answer. In this case, it is appropriate to resolve (the condition) by harmonization. Xiao Chai Hu Tang is the formula that harmonizes the exterior and interior."

The modern definition of the harmonizing method in TCM comes from the Academy of Chinese Medicine by physicians engaged in the systematization of traditional medicine in the 1950's and 1960's.

"The definition of the harmonizing method refers to harmonizing in a narrow sense. Harmonization carries the meaning of moderate use of dredging and resolving strategies. It brings balance to complex conditions that present with symptom pictures of interior-exterior, excess-deficiency, and cold-heat, as well as conditions of overabundance and debility that exist in the yin and yang organs, yin and yang, and qi and blood." (After Bensky and Barolet, Therapeutic Experiences of Pu Fu-Zhou)

In the contemporary practice of TCM, harmonizing prescriptions fall into four sub-categories: Shao Yang disorders, Liver and Spleen disharmonies, Stomach and Intestine disharmonies, and malarial disorders.

Xiao Chai Hu Tang 小柴胡汤

Xiao Chai Hu Tang was first recorded in the Shang Han Lun, and is the basis for nearly all prescriptions found in the harmonizing category. The Shao Yang region, associated with the San Jiao and Gall Bladder channels, is said to lie between the body's exterior and interior. Because the Shao Yang is neither internal nor external, releasing the exterior or purging the interior can damage the Qi and therefore aggravate the illness. Harmonization, which is the moderate use of dredging the interior and resolving the exterior, must be used in this circumstance.

The Shang Han Lun states that Shao Yang patterns are initially caused by wind-cold penetrating the surface and transforming into heat without form. This pattern is a transitional stage between the Tai Yang and Yang Ming stages. It was observed that the Qi, especially of the Spleen and Stomach, is no longer strong enough to drive the pathogen back out through the surface of the body. The pathogen enters into the intermediary region of the Shao Yang, disharmony between interior and exterior results, and the subsequent symptoms of alternating fever and chills reveal the nature of the clinical picture.

One of the most common diagnostic tools traditionally used to confirm the location of an exterior pattern is to identify the type of fever present. A Tai Yang pattern is generally indicated by fever and chills; fever without chills indicate a Yang Ming pattern; and alternating fever and chills indicate a Shao Yang pattern. It should be noted here that many patients with a Shao Yang disorder do not experience clearly identifiable sensations of alternating fever and chills. While this symptom is certainly a sign of a Shao Yang pattern, it often manifests in a subtle form. In contemporary times, most patients with Shao Yang patterns will deny experiencing alternating fever and chills. However, when asked if they experience periods of mild flushing and mild sensations of feeling chilled, they will respond in the affirmative. This is a subtle but important diagnostic observation and confirms the Shao Yang diagnosis.

Xiao Chai Hu Tang

Additional Shao Yang symptoms include dry throat, a bitter taste in the mouth, fullness of the ribs and hypochondriac region, mild dizziness or vertigo, poor appetite or digestive upset, and restlessness, irritability or depressed mood. The pulse is most often wiry/bowstring, and the tongue frequently has a mild dusky appearance.

As is common in many modern presentations of TCM patterns, the symptoms and signs seen today are often mild versions of the traditional pattern picture. This is especially true of Shao Yang patterns. This pathology is not uncommon, and very often goes unidentified by contemporary practitioners looking for more overt symptomology.

The Prescription

Xiao Chai Hu Tang is formulated to clear and dispel constrained heat trapped in the Shao Yang, tonify the Qi, and harmonize interior and exterior. Chai hu, as the chief herb, is the most effective herb in the pharmacopeia for resolving Shao Yang channel constraint. In addition, Chai hu dredges the Liver and Gall Bladder Qi, relieves distention of the ribs and hypochondriac region, and eases restlessness, irritability and depressed mood.

According to TCM theory, the Liver regulates the body's 24-hour cycle, ensures the smooth flow of Qi and Blood, regulates the emotions, and influences digestive system functioning. Essentially, the functions of the nervous system are functions ascribed to the TCM concept of the Liver. Therefore, since Chai hu is an herb that regulates the Liver (nervous system), we can understand why Chai hu has the ability to relieve distention of the ribs and hypochondriac region, dizziness, vertigo, restlessness, irritability and depressed mood.

Huang qin is the deputy and clears heat from the Liver and Gall Bladder, releases constraint, resolves toxins, and vents pathogenic influence in the Shao Yang. Huang qin and Chai hu function together to harmonize the Liver and Gall bladder and resolve Shao Yang constraint. Chai hu, being spicy and cool, smooths and frees the Liver, while also raising the Gall Bladder Qi. Huang qin, being bitter and cold, clears constrained Gall Bladder heat and sedates rising Liver Yang. Its bitter flavor also directs Qi downward, while it's light and clear aroma disperses constraint.

The assistants Fa ban xia and Sheng jiang transform turbid phlegm in the middle Jiao, direct rebellious Qi downward, and stop nausea and vomiting. Their warm and aromatic quality also benefit Spleen and Stomach function, dispel constraint and support the appetite. The other assistants, Ren shen, Da zao and Gan cao combine to strengthen the Qi, prevent pathogenic influences from going deeper into the interior, and assist in supporting the Lung's role to regulate and consolidate the surface. Finally, Sheng jiang and Da zao regulate the Ying and Wei Qi and assist Chai hu in releasing the exterior aspect of this pattern.

Xiao Chai Hu Tang

Xiao Chai Hu Tang in Contemporary Clinical Practice

In addition to Xiao Chai Hu Tang's efficacy in resolving the traditional Shao Yang pattern, it is used in treating a variety of modern clinical presentations. The following is a list of some of these additional clinical applications.

  1. External pathogenic conditions where alternating warmth and chilled feelings are present.
  2. Digestive disorders associated with Stomach and Liver Qi stagnation.
  3. Emotional complaints associated with a Shao Yang presentation that include anxiety, irritability, depressed mood, or alternating emotional symptoms.
  4. Gastrointestinal disorders associated with concurrent Liver Qi stagnation, Spleen deficiency, and damp Heat.
  5. Digestive and emotional complaints, or hypochondriac area discomfort following an external pathogenic condition.
  6. Lingering pathogen conditions or patterns.
  7. To assist in clearing irritability, anger and resentment, and in preventing the consequences of repressed emotions.
  8. Used as a regular constitutional treatment to help maintain physical, emotional and mental balance in those with a Shao Yang constitution.

Cautions and Contraindications: Patients taking interferon. Contraindicated in conditions of excess above and deficiency below, and Liver Fire. Use with caution in patients with Liver Yang Rising and hypertension.

Final Thoughts

The late-Qing dynasty physician Tang Zong-Hai, in referring to Xiao Chai Hu Tang stated:

"This is an invigorating formula that spreads out the exterior and harmonizes the interior, that lifts the clear upward and directs the turbid downward.... Thus, harmonizing and facilitating the patient's Qi dynamic, how would the surface and the three burners not also be regulated?"

Xiao Chai Hu Tang is a unique prescription within the TCM formulary, combining gentle tonification of the Qi, strengthening of the Spleen and Stomach, harmonizing of the Liver and Gall Bladder, and regulation of the surface. Additionally, the special complementary pairing of Chai hu and Huang qin frees the Liver and Gall Bladder, both enlivening and relaxing the nervous system, emotions and the Spirit. Essentially, this formula strengthens and eases, ascends and descends, consolidates and frees. This is the definition of harmonization.


  • Bensky, D. & Barolet, R., Formulas & Strategies, Eastland Press: 1990.
  • Bensky, D. et al., Chinese Herbal Medicine Materia Medica, 3rd ed., Eastland Press: 2004.
  • Liu, Guohui, Warm Pathogen Diseases, A Clinical Guide, Revised edition, Eastland Press: 2005
  • Chen, J. & Chen, T., Chinese Medical Herbology and Pharmacology, Art of Medicine Press: 2004.
  • Maclean, Will, Clinical Manual of Chinese Herbal Patent Medicines, Pangolin Press: 2003
  • Wrinkle, A. et al., A Practitioner’s Formula Guide, Elemental Essentials Press: 2008.

About the Author

Mark W. Frost, MSTCM, and licensed acupuncturist, was previously chair of the Herbal Medicine Department at the American College of Traditional Chinese Medicine in San Francisco, California where he taught in both the Masters and Doctoral Programs and served as a clinical supervisor in their Community Clinic. Mark has also been in private practice in San Francisco for more than 30 years. He is the author of numerous articles on Chinese herbal medicine and has presented at several TCM conferences since 2014.

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