主治胸胁苦满也。旁治寒热往来、腹中痛、胁下痞硬。
考 证
小柴胡汤证曰∶胸胁苦满、往来寒热。又云∶腹中痛。又云∶胁下痞硬。
柴胡加芒硝汤证曰∶胸胁满。
柴胡去半夏加栝蒌汤，证不具也。（说在互考中）
柴胡姜桂汤证曰∶胸胁满、微结。又云∶往来寒热。
大柴胡汤证曰∶心下急、郁郁微烦。又曰∶往来寒热。又曰∶心下满痛。
以上五方，柴胡皆八两。
柴胡桂枝汤证曰∶心下支结。
以上一方，柴胡四两而八两之例。
上历观此诸方，柴胡主治胸胁苦满也。其他治往来寒热、或腹中痛、或呕吐、或小便不
利，此一方之所主治。而非一味之所主治也。为则按∶《伤寒论》中，寒热、腹痛、呕吐、
小便不利，而不用柴胡者多矣。胸胁苦满而有前证，则柴胡主焉。此可以见柴胡之所主治也。
互 考
柴胡去半夏加栝蒌汤，其证不具也。以渴，故代半夏以栝蒌也。今试诸世所谓疟疾，胸
胁苦满而渴者，甚有效焉。其无有胸胁苦满证，则终不知也。然则胸胁苦满证，其脱也明矣。
辨 误
《本草纲目》柴胡部中，往往以往来寒热为其主治也。夫世所谓疟疾，其寒热往来也剧
矣；而有用柴胡而治也者，亦有不治也者。于是质之仲景氏之书，其用柴胡也，无不有胸胁
苦满之证。今乃施诸胸胁苦满而寒热往来者，其应犹响之于声。非直疟也，百疾皆然。无胸
胁苦满证者，则用之无效焉。然则柴胡之所主治，不在彼而在此。
品 考
柴胡 处处出焉。本草以产于银州银县者为上品也。本邦药铺所鬻者有二品。曰镰仓柴
胡，曰河原柴胡也。盖河原柴胡者，非柴胡之种也，不可用焉。镰仓柴胡者尤佳，去须及头，
以粗布指拂拭之，锉而用焉。雷 、陈子承，称柴胡香气甚矣。而本邦之产，比诸产汉土者，
形状则同，气味则薄，因稽诸说。嫩则香美也，老则不也。张元素曰∶气味俱清，故今用镰
仓柴胡也。
柴胡主治胸胁苦满（胸胁部胀满不适）。兼治寒热往来（忽冷忽热）、腹中痛、胁下痞硬（胁肋下方感觉痞塞坚硬）。
考证
小柴胡汤证表现为：胸胁苦满、往来寒热。又说：腹中痛。又说：胁下痞硬。
柴胡加芒硝汤证表现为：胸胁满。
柴胡去半夏加栝蒌汤的证候表现不完整。（详见互考部分）
柴胡姜桂汤证表现为：胸胁满、微结（轻微结滞）。又说：往来寒热。
大柴胡汤证表现为：心下急（胃脘部拘急不适）、郁郁微烦（情绪抑郁且轻微烦躁）。又说：往来寒热。又说：心下满痛（胃脘部胀满疼痛）。
以上五个方剂，柴胡的用量均为八两。
柴胡桂枝汤证表现为：心下支结（胃脘部有支撑感且结滞）。
以上这一个方剂，柴胡用量为四两，不符合八两的惯例。
综上所述，纵观上述各方，柴胡的主治功效在于胸胁苦满。其他如治疗往来寒热、或腹中痛、或呕吐、或小便不利，这是整个方剂所主治的范围，而非单味药柴胡的主治功效。作者按语认为：在《伤寒论》中，出现寒热、腹痛、呕吐、小便不利等症状而不用柴胡的情况有很多。如果具备胸胁苦满并伴有前述症状，则使用柴胡为主药。这就可以看出柴胡真正的主治功效所在。
互考
柴胡去半夏加栝蒌汤的证候表现不完整。因为患者口渴，所以用栝蒌替代半夏。如今尝试将其用于世人所说的疟疾，凡是有胸胁苦满且口渴的患者，疗效甚佳。如果没有胸胁苦满这一证候，则最终无法确定其疗效。由此可见，胸胁苦满这一证候是不可或缺的。
辨误
《本草纲目》柴胡条目中，往往将往来寒热作为其主治功效。世人所说的疟疾，其寒热往来的症状非常剧烈；有的使用柴胡治疗有效，有的则无效。于是查阅张仲景的著作，发现凡是使用柴胡的病例，无不具备胸胁苦满这一证候。如今若将其应用于既有胸胁苦满又有寒热往来的患者，其疗效如同回声应和声音一样迅速准确。不仅限于疟疾，各种疾病都是如此。没有胸胁苦满证候的患者，使用柴胡则无效。由此可见，柴胡的主治功效不在于寒热往来，而在于胸胁苦满。
品考
柴胡各地均有出产。本草书籍认为产于银州银县的为上品。我国（日本）药店出售的柴胡有两种：镰仓柴胡和河原柴胡。其中河原柴胡并非真正的柴胡品种，不可使用。镰仓柴胡尤为优良，需去除须根及头部，用粗布擦拭干净，切碎后使用。雷敩、陈承称柴胡香气浓郁。而本国产的柴胡，与产自汉地（中国）的相比，形状相同，但气味淡薄，因此考察相关学说。嫩叶香气美好，老叶则不然。张元素说：柴胡气味清淡，因此现在使用镰仓柴胡。
Chai Hu (Bupleuri Radix) primarily treats Xiong Xie Ku Man (distending fullness and discomfort in the chest and hypochondrium). It also treats Wang Lai Han Re (alternating chills and fever), Fu Zhong Tong (abdominal pain), and Xie Xia Pi Ying (a sensation of stuffiness and hardness under the hypochondrium).
Textual Research
The syndrome pattern of Xiao Chai Hu Tang (Minor Bupleurum Decoction) is described as: Xiong Xie Ku Man, Wang Lai Han Re. It further states: Fu Zhong Tong. And again: Xie Xia Pi Ying.
The syndrome pattern of Chai Hu Jia Mang Xiao Tang (Bupleurum Decoction with Niter) is described as: Xiong Xie Man (fullness in the chest and hypochondrium).
The syndrome pattern of Chai Hu Qu Ban Xia Gua Lou Tang (Bupleurum Decoction without Pinellia plus Trichosanthes Root) is not fully specified. (See Mutual Examination below).
The syndrome pattern of Chai Hu Jiang Gui Tang (Bupleurum Decoction with Ginger and Cinnamon Twig) is described as: Xiong Xie Man, Wei Jie (slight binding/stagnation). It further states: Wang Lai Han Re.
The syndrome pattern of Da Chai Hu Tang (Major Bupleurum Decoction) is described as: Xin Xia Ji (urgency and tightness in the epigastrium), Yu Yu Wei Fan (depressed mood with slight irritability). It further states: Wang Lai Han Re. And again: Xin Xia Man Tong (fullness and pain in the epigastrium).
In the above five formulas, the dosage of Chai Hu is consistently eight liang.
The syndrome pattern of Chai Hu Gui Zhi Tang (Bupleurum and Cinnamon Twig Decoction) is described as: Xin Xia Zhi Jie (supporting knotting in the epigastrium).
In this single formula, the dosage of Chai Hu is four liang, which deviates from the eight-liang convention.
Having reviewed these formulas comprehensively, it is evident that Chai Hu's primary indication is Xiong Xie Ku Man. Other symptoms such as Wang Lai Han Re, or Fu Zhong Tong, or Ou Tu (vomiting), or Xiao Bian Bu Li (difficulty in urination), are indications treated by the formula as a whole, not by the single herb Chai Hu alone. The author notes that in Shang Han Lun (Treatise on Cold Pathogenic Diseases), there are many cases involving chills/fever, abdominal pain, vomiting, or difficulty in urination where Chai Hu is not used. However, when Xiong Xie Ku Man is present along with the aforementioned symptoms, Chai Hu is indicated. This demonstrates the true primary indication of Chai Hu.
Mutual Examination
The syndrome pattern for Chai Hu Qu Ban Xia Gua Lou Tang is incomplete. Because of thirst (Ke), Ban Xia (Pinelliae Rhizoma) is replaced by Gua Lou (Trichosanthis Radix). Currently, when applied to what is commonly known as malaria, patients presenting with Xiong Xie Ku Man and thirst respond very well. If the symptom of Xiong Xie Ku Man is absent, the efficacy remains unknown. Thus, it is clear that the presence of Xiong Xie Ku Man is essential.
Correcting Misconceptions
Ben Cao Gang Mu (Compendium of Materia Medica) often lists Wang Lai Han Re as the primary indication for Chai Hu. Malaria, as commonly understood, presents with severe alternating chills and fever; some cases respond to Chai Hu treatment, while others do not. Consulting Zhang Zhongjing's works, it is found that every case using Chai Hu invariably includes the symptom of Xiong Xie Ku Man. Therefore, applying Chai Hu to patients who have both Xiong Xie Ku Man and Wang Lai Han Re yields results as immediate as an echo responding to a sound. This applies not only to malaria but to various diseases alike. For patients lacking the Xiong Xie Ku Man syndrome, Chai Hu is ineffective. Consequently, Chai Hu's primary indication lies not in treating alternating chills and fever, but in treating Xiong Xie Ku Man.
Product Examination
Chai Hu grows in many places. Materia Medica texts consider those produced in Yin Zhou, Yin County, as the highest grade. In our country (Japan), pharmacies sell two types: Kamakura Chai Hu and Kawara Chai Hu. Kawara Chai Hu is not a true species of Chai Hu and should not be used. Kamakura Chai Hu is superior; the rootlets and head must be removed, wiped clean with coarse cloth, sliced, and used. Lei Xiao and Chen Cheng stated that Chai Hu has a strong aroma. However, the domestic product, compared to those from Han Tu (China), has the same shape but a weaker aroma. Investigating relevant theories, tender leaves have a fine aroma, whereas old ones do not. Zhang Yuan Su said: "Its flavor and qi are light/clear." Therefore, Kamakura Chai Hu is currently used.