A classic "half-interior, half-exterior" formula from the Han dynasty, one of the most frequently discussed shao-yang remedies in Chinese households and the ancestor of dozens of later variations.
Cultural reference - how this formula has been discussed in Chinese medical tradition. Not medical advice.
Background & origin
Compiled by Zhang Zhongjing in the "Treatise on Cold Damage" (《伤寒论》) around 200 CE as the canonical shao-yang stage formula. In Japan, Xiao Chaihu Tang is one of the most important kampo prescriptions, sold by every major manufacturer (Tsumura, Kracie, Kotaro, JPS) and used as the base for over a dozen derivative formulas. In Korea it appears as Soshiho-tang (소시호탕) in the standard Kyungdong hanbang line. It is, in short, one of the most cross-culturally reproduced Chinese formulas in existence.
From the source text
This page is cultural documentation, not medical advice.
From the source text · 卷三·辨太阳病脉证并治中·第 96 条
Classical text
伤寒五六日，中风，往来寒热，胸胁苦满，默默不欲饮食，心烦喜呕，或胸中烦而不呕，或渴，或腹中痛，或胁下痞硬，或心下悸，小便不利，或不渴，身有微热，或咳者，小柴胡汤主之。
Modern Chinese rendering
用于伤寒或中风已过五至六日，症见寒热往来、胸胁部位胀满不适、沉默不语、不思饮食、心烦、频繁呕吐；或兼见胸中烦闷而不呕、口渴、腹中痛、胁下痞硬、心下悸、小便不利、不渴而身有微热、或咳嗽者。这是少阳病主方，"往来寒热"是少阳病的代表性热型。
Editorial translation
Used when, five or six days into a cold-damage or wind-strike disorder, the patient presents with alternating chills and fever, fullness and discomfort in the chest and flanks, a taciturn and uncommunicative manner, no desire to eat, irritability, and frequent vomiting — together with possible secondary signs such as chest vexation without vomiting, thirst, abdominal pain, hardening and fullness below the flanks, palpitations beneath the heart, dysuria, feverishness without thirst, or cough. This is the canonical shao-yang formula; "alternating chills and fever" is the representative fever pattern of the shao-yang stage.
In tradition
In TCM tradition, associated with the "shao-yang" pattern, a state in which an external pathogen is felt to linger between the surface and the interior: alternating sensations of cold and warmth, fullness or discomfort in the chest and flanks, a bitter taste in the mouth, dry throat, dizziness, poor appetite, and occasional nausea or vomiting. It is also one of the formulas most often discussed in the context of menstrual and perimenstrual discomfort, and in Japan is the foundational prescription from which dozens of derivative kampo formulas are built.
Formula composition
Monarch1
- Bupleurum root (Chái Hú / 柴胡)
Minister1
- Scutellaria root (Huáng Qín / 黄芩)
Assistant5
- Ginseng (Rén Shēn / 人参)
- Pinellia rhizome, processed (Bàn Xià / 半夏)
- Licorice root, honey-fried (Zhì Gān Cǎo / 炙甘草)
- Ginger (Shēng Jiāng / 生姜)
- Chinese date (Dà Zǎo / 大枣)
International availability
Cautions & context
- Considered unsuitable during an active "heat" condition with high fever in TCM framing, the formula is described as "harmonizing" rather than "clearing heat".
- People on interferon or immunosuppressant therapies are typically advised to consult a physician, some ingredients have documented immunomodulatory effects.
- Not recommended during pregnancy without qualified guidance; some sources consider Pinellia and bupleurum inappropriate in early pregnancy.
- Symptoms that worsen or do not improve within a few days should be reassessed by a clinician, persistent alternating fever and chills can have many causes.
Related formulas
Other formulas from this text· "Treatise on Cold Damage"
Other formulas by this contributor· Zhang Zhongjing
Related concerns
Concern · digestion
Digestion
Upper-abdominal heaviness, bloating, sour reflux, loose stools, traveler's stomach, and the aftermath of a meal that was richer, spicier, or larger than usual.
Concern · immune
Immune Support
The everyday language of "wanting to stay well", a sense of being run down, the change of seasons, occasional mouth ulcers, the slow recovery after a cold.
Editorial note
Compiled from "Treatise on Cold Damage" (200).
Last reviewed: July 18, 2026
Three layers of evidence
Classical source
≈ 1800 years · "Treatise on Cold Damage" (200)
Pharmacopoeia indication
"Release the exterior and disperse heat, soothe the liver and harmonize the stomach. Used for externally-contracted disease with pathogen invading the Shaoyang layer: alternating chills and fever, chest and hypochondriac fullness and discomfort, poor appetite, irritability with frequent vomiting, bitter taste in the mouth, and dry throat."
Modern research status
As of 2026-07-18, a PubMed search using the formula name and the Latin / Korean / Japanese transliterations together with "systematic review" and "meta-analysis" did not identify a dedicated systematic review for this formula. Any clinical evidence that does exist is fragmented across small individual trials or covered in broad herbal-medicine umbrella reviews, which do not allow a per-formula evidence assessment; the absence of a dedicated SR is itself the relevant editorial fact here.
References
References reviewed on July 18, 2026 · PubMed search on 2026-07-18
- 01ClassicalZhang Zhongjing, 《伤寒论》 (Shānghán Lùn / Treatise on Cold Damage), Eastern Han dynasty, c. 200 CE, the canonical shao-yang stage source, with the base formula appearing in clause 96 of the "taiyang" section.
- 02TextbookDuan Fuqin (段富津) et al. (eds.), 《方剂学》 (Fāngjìxué / Textbook of Formulas), Shanghai Scientific and Technical Publishers, 1995, the standard modern university-level formula textbook in mainland China, with Xiao Chaihu Tang analysed as the representative "harmonize shao-yang" formula.
- 03PharmacopoeiaChinese Pharmacopoeia Commission, 《中华人民共和国药典》 2020 年版一部 (Zhōnghuá Rénmín Gònghéguó Yàodiǎn, Pharmacopoeia of the People's Republic of China, 2020 Edition, Vol. I), China Medical Science Press, 2020, the official monograph for Xiao Chaihu Pian / Xiao Chaihu Tang dosage forms.