少阳之为病。口苦咽干目眩也。
少阳者。足少阳胆经也。胆为东方初生之木。名之曰少阳者。天地之阳气生于黄泉。则草木之根 。
勾萌于至阴坤土之中。谓之厥阴。至三阳开泰。阳气透地。则萌芽生动。二月而阳气上腾。以雷霆之鼓。
风雨之润。而草木条达。阳气附于草木而初生。故为之少阳。人身以脏腑居于躯壳之中者为三阴。阳气
由命门而出。为无形之三焦。难经所谓
命门为三焦之原是也。三焦附于肝胆。犹天地之阳气附于草木也。是为少阳。主乎躯壳之里层。由此而
盛阳外布于肌肉而为阳明。行于营卫。达于皮毛而为太阳矣。灵枢经脉篇云。足少阳之脉。起于目锐 。
出走耳前。至目锐 后。下颈入缺盆。邪在少阳之经。故目眩而咽干。又云是动则病口苦。善太息。
且手少阳脉之支者。亦走耳前。至目锐 。动则病耳聋嗌肿喉痹。故少阳之为病。口苦咽干目眩也。
伤寒中风。五六日往来寒热。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。与小柴胡汤主之。
五六日。六经传邪之候也。往来寒热者。或作或止。或早或晏。非若疟之休作有时也。以五六日而
尚往来寒热。则知邪未入阴。犹在少阳也。少阳之脉。虽行身之侧。而其实则躯壳之里层也。向外则由阳
明达太阳而为三阳。表也。向内则躯壳中之脏腑为三阴。里也。少阳居于表里之间。故为半表半里。邪在
少阳。则所入已深。卫气周行一身。故邪气与卫气合则病作。与卫气离则病休。卫气旋转流行。如环无端。
故其寒热之作。必待正邪相遇。所以有往来之不齐也。非若太阳居表之最外一层。营卫所在。邪气入之。
即寒热不休也。其所以寒热者。疟论所谓邪并于阳则阳胜。并于阴则阴胜。阴胜则寒。阳胜则热也。胸胁苦
满者。少阳脉之支者。别锐 。下大迎。合于少阳。下颊车。自颈合缺盆以下胸中。贯膈络肝属胆。循胁里。
出气街。其直者从缺盆下腋。循胸过季胁。邪入其经。故胸胁苦满。或胁下痞硬也。胸胁苦满。故默默不
欲饮食。然邪在半里。为入阴之渐。且少阳与厥阴相为表里。所以如厥阴证之默默不欲食。及饥不欲食。
或腹中痛也。邪热在胸。故心烦喜呕。或但胸中烦而不呕。或心下筑筑然悸动也。或渴或不渴者。寒热往
来。或作或止。即疟论所云或甚或不甚。故或渴或不渴也。邪在半表。故身有微热。少阳之脉下胸中。
邪入胸中而犯肺。故或咳也。或者。或有或无。非必皆有也。大凡邪气在表。表实则当汗解。邪气在里。
里实则当攻下。邪在膈上。将次入里。则当用吐。今邪在半表半里之间。汗之则达表之途远。误汗则
阳气虚而邪必犯胃。恐有谵语烦悸之变生。吐下则内陷之机速。误吐下则正气伤而虚邪内侵。恐有惊
悸之患作。故汗吐下皆在所禁。而以小柴胡汤和解其半表半里之邪也。以下凡称少阳病者。其见证皆具
载此二条中。虽未必全见。或见一二证者。即谓之少阳病也。
小柴胡汤方
柴胡（半斤） 黄芩（三两） 人参（三两） 甘草（三两） 半夏（半升） 生姜（三两切）
大枣（十二枚擘）
上七味。以水一斗二升。煮取六升。去滓。再煎取三升。温服一升。日三服。
柴胡汤而有大小之分者。非柴胡有大小之异也。盖以其用之轻重。力之大小而言也。大柴胡汤能两
解表里之邪者。以柴胡汤解其半表之邪。而以大黄攻下其在里之实邪。其功力较大。故谓之大。小柴
胡汤。兼能和解半表半里之邪。且可以调护其正气。其功用较缓。故谓之小也。夫小柴胡汤。乃升发
少阳之要剂也。草木得阳气而升发。阳气出地而发生草木。阳气附于草木。故木为少阳。若木得邪气而
抑郁不舒。则少阳之气。不能宣布其发生矣。故六元正纪大论云。木郁则达之。木气条达。则少阳之
气升发。天地变化而草木蕃矣。人身之阳气。由肾水中命门而出。从
三阴而始达少阳。若为邪气所遏。其气不得由阳明而达太阳。邪客其经。所以往来寒热。胸胁满而胁下痞硬。
或呕或渴之证。肝胆受邪。故口苦咽干目眩也。邪在少阳。内逼三阴。达表之途辽远。汗之徒足以败卫亡阳。
少阳虽外属三阳。而入里之路较近。下之适足以陷邪伤胃。汗下俱所不宜。故立小柴胡汤以升发少阳之郁邪。
使清阳达表而解散之。即所谓木郁达之之义也。故少阳一经。惟此一方。无他法也。虽有多证。亦不过因此
出入变化而已。至变证已离少阳。柴胡不中与之。则更用他法矣。虽后人之补中益气汤及逍遥散之类。其升
发清阳开解郁结之义。亦皆不离小柴胡之旨也。方用柴胡为君者。李时珍云。柴胡乃手足厥阴少阳之药。
劳在脾胃有热。或阳气下陷。则柴胡乃引清气。退热必用之药。李东垣谓能引清气而行阳道。伤寒外诸有热
则加之。无热则不必也。又能引胃气上行。升腾而行春令。又凡诸疟。以柴胡为君。随所在经。分佐以引经
之药。十二经疮疽中。须用以散诸经血结气聚。愚按所谓清气者。下焦所升清阳之气也。谓之清阳者。盖谷之
浊气降于下焦。为命门真阳之所蒸。其清气腾达于上。聚膻中而为气海。通于肺而为呼吸。布于皮肤而为
卫气。营运于周身内外上中下而为三焦。附于肝胆而为少阳风木。故清阳不升。内无以达生发阳和之气。所
以外不能驱邪出表矣。阴阳应象论云。清气在下。则生飧泄。浊气在上。则生 胀。此阴阳反作。病之逆从也。
因此而东垣有能引胃气上行。升腾而行春令之语。濒湖有脾胃有热。阳气下陷。引清气而退热之用。是下焦
之真阳虚。则当以温补命门为主。下焦之真阳不上行。则当以升发清阳为急。必使阳气营运。清阳出上窍。
浊阴出下窍。清阳发腠理。浊阴走五脏。清阳实四肢。浊阴归六腑。然后阴阳各得其用也。小柴胡汤之用柴胡。
盖取其清阳发腠理也。黄芩者。佐柴胡而彻其热也。藏气法时论云。肝苦急。急食甘以缓之。故用
人参甘草之甘缓。胆为奇恒之府。其精汁无余。所以藏而不泻。与他腑之传化不同。况少阳为春生之
始气。春气旺则百物皆生。故十一脏皆取决焉。手少阴三焦以气为用。气不旺。则不能运化流行。故以人参助
其升发营运之力也。其在本方。已有因证加减之法。今世俗皆弃人参而不用。以为稳当。乃盲医不知
虚实之故也。惟热盛而邪实者。乃可去之。或有兼证之不相合者。亦可去也。若邪轻而正气虚者。未可概去也。
或邪气虽盛而正气大虚者。亦当酌其去取也。如柴胡桂枝汤。虽发热微恶寒。支节烦疼。微呕而心下支结。
为外证未去。乃太少兼证。故于小柴胡之半剂。加入桂枝汤之半以两解之。而人参仍不去也。又如柴胡桂枝干
姜汤。虽已发汗而复下之。不为不虚矣。又以胸胁满而微结。但头汗出。往来寒热。非惟少阳之邪未解。
太阳亦未解也。故增入桂枝干姜栝蒌牡蛎。而人参半夏姜枣皆减去矣。又如柴胡加芒硝汤。虽有潮热胃实之证。
以其胸胁满而呕。本属柴胡证。奈以非其治之丸药下之。致成少阳坏病。故但加芒硝而人参仍不去也。更如大
柴胡汤。以太阳病而过经十余日。反二三下之。亦可谓虚矣。更后四五日而柴胡证仍在。故先与小柴胡汤。服
汤而呕不止。心下反急。郁郁微烦不解者。盖因邪自太阳误下入里。且柴胡证仍在。故仍以柴胡解少阳之邪。
加入大黄枳实。以攻入里之邪。合而为两解表里之剂。然以太阳入里之热邪未去。所以竟去人参也。若此之类。
皆去取之法。仍小柴胡汤之变法也。总之邪气独在少阳。未见有去人参者。若兼太阳表症。及阳明胃实者。未有
不去人参者也。若能得其去取之旨。便能随证加减。无不得心应手矣。半夏辛温滑利。可以去胸胁之满。及痞
硬之邪。即半夏泻心之义。非独治痰蠲饮也。生姜辛而能散。大枣甘而和缓。可以和营卫而调其往来之寒热也。
以一方而该一经之证。苟非灵机活泼。随证转移。曷足以尽其变哉。
后加减法
若胸中烦而不呕。去半夏人参。加栝蒌实一枚。
伤寒郁热之邪。及中风之阳邪在胸。皆可发烦。邪在少阳可烦。太阳之邪在胸亦烦。以邪热抟聚于胸中而
烦闷。不宜补气。故去人参。外邪犯胃。寒饮聚于胃口则呕。故用半夏之辛温滑利以蠲饮。若不呕。则邪
未犯胃。饮未抟结。故去半夏也。栝蒌实甘寒润燥。降火治咳嗽。故加之以去胸邪而止烦热。李时珍云。
张仲景治胸痹痛引心背。咳唾喘息。及结胸满痛。皆用栝蒌实。乃取其甘寒不犯胃气。能降上焦之火。使痰气
下降也。成氏不知此意。乃云苦寒以泻热。盖不尝其味。随文附会耳。然栝蒌之性滑。半夏亦滑。因栝蒌
甘寒。宜于烦热。半夏辛温。故不用也。
若渴者去半夏。加人参合成四两半。栝蒌根四两。
半夏辛辣而温热。故不宜于燥渴。栝蒌根苦寒而能彻热生津。故宜加入。增人参者。所以益气而添津液也。
若腹中痛者。去黄芩。加芍药三两。
腹痛为太阴脾病。张元素云。芍药白补赤散。能泻肝益脾胃。酒浸行经。上中部腹痛。与姜同用。温经散
湿通塞利腹中痛。胃气不通。白芍入脾经。补中焦。乃下利必用之药。盖泻利皆太阴病。故不可缺。得甘草为佐。
治腹中痛。热则少加黄芩。寒则加桂。此仲景神方也。李时珍谓白芍益脾。能于土中泻木。赤芍散邪。能行血
中之滞。日华言赤补气。白治血。欠审矣。如此。则丹溪所云腹痛多是血脉凝涩。亦必酒炒用。然止能治血虚
腹痛。余并不治之说。非确论矣。腹痛已属太阴。黄芩寒中。故去之。愚谓太阴腹痛者。合温药治之则可。
若兼阳明胃实。腹满而痛。当用承气汤者。非芍
药所能治。若腹虽痛而有表邪未去者。亦未可用。不可概以芍药为腹痛必用之药也。
若胁下痞硬。去大枣。加牡蛎四两。
少阳之经脉下胸中。贯膈属肝络胆。循胁里。邪入其络。故胁下痞硬。去大枣者。恐其甘缓也。牡蛎之加。成
氏谓咸以软坚而已。后人皆附会焉。不知仲景但以之治胁下痞硬。而不用之以治心下痞硬。则知不但咸以软坚。
并可以平肝邪而入少阳之络矣。神农本经不言及此。惟名医别录有治心胁下痞热之语。王好古亦云。以柴胡引之。
能去胁下硬。以茶引之。能消项上结核。以大黄引之。能消股间肿。以地黄为使。能益精涩小便。想亦有所自也。
柴胡龙骨牡蛎汤中。用之以治胸满烦惊。不可转侧。亦所以平木气而解少阳之邪也。岂止咸以软坚之用耶。
若心下悸。小便不利者。去黄芩。加茯苓四两。
悸者。惕惕然跳动之谓也。然有心下心中脐下之不同。如心中悸而烦者。小建中汤之悸也。脉结代而心动
悸者。炙甘草汤之悸也。发汗过多。叉手冒心而悸者。桂枝甘草汤之悸也。汗出不解。发热心下悸。头眩身 动。
振振欲擗地者。真武汤之悸也。发汗后。脐下悸。欲作奔豚者。茯苓桂枝甘草大枣汤之悸也。凡此诸悸。皆太
阳误治之虚邪所致也。即少阳中风。两耳无闻。目赤胸满而烦者。亦因吐下之虚而致惊悸也。虽伤寒脉弦细。
头痛发热者。已属少阳。若误汗之。致胃不和而谵语者。当以小承气和胃则愈。其证似乎胃实。然亦因邪在少阳。
不可汗而汗之。邪乘误汗之虚。陷入于胃。胃不和则烦而悸耳。亦虚邪也。至于三阴之悸。皆阴盛阳虚。可不言
而喻矣。所以阳明一经。实邪居多。故绝无悸病。惟太阳病而小便利者。饮水多。必心下悸。小便少者。必苦
里急之一条。与此义相符。盖以太阳之热邪。
尚未入腑。膀胱无热。故小便通利。里既无热。所以饮水多则水寒停蓄。胃气不得流行。故心下筑筑然悸动也。况于
小便不利者乎。此以少阳虚无之腑。以气为用。邪气犯之则虚。故小柴胡汤中有人参之补。虽非饮水多而致心下
悸。以小便不利。亦必三焦不运。阳气不行。水饮停蓄于胃。故令心下悸也。去黄芩者。恶其寒中也。加茯苓者。
取其淡渗。其性上行而下降。利水而泻下。若小便得利。悸自当止耳。然既去黄芩之寒中。加茯苓之淡渗。
则知中气已寒。倘下焦无火。气化不行。设小便仍不利者。五苓散或可采择也。
若不渴。外有微热者。去人参。加桂三两。温覆取微汗愈。
不渴则邪未入里。外有微热则表证未除。去人参者。恐其固太阳之表邪也。然何以知其为太阳之表邪乎。
观加桂去人参。则知为太阳之表邪矣。温覆取微汗。所以解太阳之风邪也。所谓加桂者。乃桂枝。非桂肉也。李东
垣曰。经云。味薄则发泄。故桂枝上行而达表。味浓则发热。桂肉下行而补肾。此但曰加桂而未云桂枝。然以温覆
取微汗推之。知其为桂枝无疑矣。传写脱落。其义可见。
若咳者。去人参大枣生姜。加五味子半升。干姜二两。
The principal manifestations of Shaoyang disease are: bitter taste in the mouth, dryness of the throat, and vertigo (dizziness).
Shaoyang refers to the Foot-Shaoyang Gallbladder Meridian. The Gallbladder belongs to the Wood Qi of the East in its initial generation stage. It is called "Shaoyang" because the Yang Qi of Heaven and Earth is born from deep underground (the Yellow Springs). At this time, the roots of grass and trees just begin to sprout within the extreme Yin Kun Earth, which is referred to as Jueyin. When the Three Yangs open and prosperity arrives, Yang Qi penetrates the ground, and buds begin to grow actively. In the second month, Yang Qi ascends, aided by the stirring force like thunder and the moisture like wind and rain, allowing grass and trees to stretch and develop smoothly. Yang Qi attaches itself to the initially generated grass and trees; therefore, it is termed "Shaoyang." In the human body, the Zang-Fu organs reside within the shell of the body and belong to the Three Yins. Yang Qi issues from the Gate of Vitality (Mingmen), forming the invisible Sanjiao (Triple Burner). As stated in the *Nan Jing* (Classic of Difficult Issues), "The Gate of Vitality is the origin of the Sanjiao." The Sanjiao attaches to the Liver and Gallbladder, just as the Yang Qi of Heaven and Earth attaches to grass and trees; this constitutes Shaoyang. Shaoyang governs the inner layer of the body shell. From here, outwardly, abundant Yang Qi spreads into the muscles to become Yangming; running through the Ying (Nutritive) and Wei (Defensive) levels and reaching the skin and hair to become Taiyang. The *Ling Shu: Jing Mai Chapter* states: The Foot-Shaoyang meridian originates at the outer canthus, moves anterior to the ear, reaches behind the outer canthus, descends along the neck, and enters the supraclavicular fossa (Quepen). When pathogenic factors invade the Shaoyang meridian, vertigo and dryness of the throat occur. It also states: When the meridian is disturbed, diseases such as bitter taste in the mouth and frequent sighing arise. Furthermore, the branch of the Hand-Shaoyang meridian also passes anterior to the ear and reaches the outer canthus; when disturbed, it causes deafness, swelling of the throat, and throat obstruction. Therefore, the manifestations of Shaoyang disease include bitter taste in the mouth, dryness of the throat, and vertigo.
In Cold Damage or Wind Strike, after five to six days, symptoms of alternating chills and fever appear, with bitterness and fullness in the chest and hypochondrium, silent desire not to eat, irritability, and a tendency to vomit. Alternatively, there may be irritability in the chest without vomiting, thirst, abdominal pain, hardness and stuffiness under the hypochondrium, palpitations in the epigastrium, difficulty in urination, absence of thirst, slight fever on the body, or coughing. In such cases, Xiao Chai Hu Tang (Minor Bupleurum Decoction) should be administered as the primary treatment.
Five to six days represent the period for the transmission of pathogens through the Six Channels. Alternating chills and fever refer to episodes that start and stop, occurring early or late, unlike malaria which has fixed times of onset and remission. Since alternating chills and fever persist after five to six days, it indicates that the pathogen has not entered the Yin channels but remains in Shaoyang. Although the Shaoyang meridian runs along the side of the body, its actual location is the inner layer of the body shell. Outwardly, it connects via Yangming to Taiyang, constituting the Exterior; inwardly, the Zang-Fu organs within the shell constitute the Three Yins, representing the Interior. Shaoyang resides between the Exterior and Interior, hence it is termed Half-Exterior and Half-Interior. When the pathogen is in Shaoyang, it has penetrated deeply. The Wei (Defensive) Qi circulates throughout the body; thus, when the pathogen combines with the Wei Qi, the disease manifests, and when they separate, the disease rests. The Wei Qi rotates and flows continuously like an endless circle; therefore, the occurrence of chills and fever requires the encounter of Righteous Qi and Pathogenic Qi, resulting in irregular alternation. This differs from Taiyang, which occupies the outermost layer where Ying and Wei Qi reside; once pathogens enter, chills and fever do not cease. The mechanism of chills and fever is described in the *Ma Lun* (Treatise on Malaria): when pathogens merge with Yang, Yang prevails; when they merge with Yin, Yin prevails. Yin prevalence causes chills, and Yang prevalence causes fever.
Bitterness and fullness in the chest and hypochondrium occur because the branch of the Shaoyang meridian diverges from the outer canthus, descends to Daying, merges with the Shaoyang meridian, goes down to Jiache, converges at the neck with Quepen, and descends into the chest, piercing the diaphragm, connecting with the Liver and belonging to the Gallbladder, following the interior of the hypochondrium, and emerging at Qichuan. The main trunk descends from Quepen to the axilla, follows the chest past the lateral costal margin. When pathogens invade this meridian, bitterness and fullness in the chest and hypochondrium, or hardness and stuffiness under the hypochondrium, result. Due to this fullness, there is silence and lack of appetite. However, since the pathogen is in the semi-interior, it marks the gradual entry into Yin. Moreover, Shaoyang and Jueyin are exterior-interior partners; thus, symptoms resembling Jueyin syndrome, such as silence and lack of appetite, hunger without desire to eat, or abdominal pain, may occur. Pathogenic heat in the chest causes irritability and a tendency to vomit, or merely irritability in the chest without vomiting, or palpitations in the epigastrium. Thirst or absence thereof corresponds to the intermittent nature of chills and fever, as mentioned in the *Ma Lun* ("sometimes severe, sometimes mild"), leading to occasional thirst or none. The pathogen being in the half-exterior results in slight fever on the body. The Shaoyang meridian descends into the chest; when pathogens invade the chest and affect the Lung, coughing may occur. The term "or" indicates presence or absence, not necessarily all symptoms appearing simultaneously. Generally, if pathogens are in the Exterior and the Exterior is excess, sweating should be used to resolve them; if in the Interior and the Interior is excess, purgation should be used; if in the upper Jiao approaching the Interior, emesis should be used. Now, with pathogens in the Half-Exterior and Half-Interior, using sweating is too distant for reaching the Exterior; erroneous sweating leads to deficiency of Yang Qi and invasion of pathogens into the Stomach, risking delirium, irritability, and palpitations. Using emesis or purgation accelerates the tendency for internal collapse; erroneous use damages Righteous Qi and allows empty pathogens to invade internally, risking palpitations and fright. Therefore, sweating, emesis, and purgation are all contraindicated. Instead, Xiao Chai Hu Tang is used to harmonize and resolve pathogens in the Half-Exterior and Half-Interior. All subsequent references to Shaoyang disease present symptoms documented in these two clauses. Even if not all symptoms are present, observing one or two suffices to diagnose Shaoyang disease.
Xiao Chai Hu Tang Formula
Chai Hu (Bupleuri Radix) - 8 liang
Huang Qin (Scutellariae Radix) - 3 liang
Ren Shen (Ginseng Radix) - 3 liang
Gan Cao (Glycyrrhizae Radix et Rhizoma) - 3 liang
Ban Xia (Pinelliae Rhizoma) - 0.5 sheng
Sheng Jiang (Zingiberis Rhizoma Recens) - 3 liang, sliced
Da Zao (Jujubae Fructus) - 12 pieces, split
These seven ingredients are boiled in 12 dou of water until reduced to 6 dou. Strain the dregs, then boil again to obtain 3 dou. Take 1 dou warm, three times daily.
The distinction between Da Chai Hu Tang (Major Bupleurum Decoction) and Xiao Chai Hu Tang lies not in the herb Bupleurum itself, but in the weight of dosage and strength of action. Da Chai Hu Tang resolves both Exterior and Interior pathogens by using Chai Hu Tang to resolve Half-Exterior pathogens and Da Huang (Rhei Radix et Rhizoma) to purge Interior excess pathogens, possessing greater power, hence "Major." Xiao Chai Hu Tang harmonizes Half-Exterior/Half-Interior pathogens and supports Righteous Qi, acting more gently, hence "Minor." Xiao Chai Hu Tang is a crucial formula for ascending and generating Shaoyang Qi. Grasses and trees ascend and generate upon receiving Yang Qi; Yang Qi emerges from the earth to generate plants, attaching to them. Thus, Wood corresponds to Shaoyang. If Wood is constrained by pathogens and cannot舒展 (stretch/relax), Shaoyang Qi cannot disseminate its generating function. As stated in the *Su Wen: Liu Yuan Zheng Ji Da Lun*: "When Wood is constrained, it must be dispersed." When Wood Qi is smooth and unobstructed, Shaoyang Qi ascends, heaven and earth change, and flora flourishes. Human Yang Qi issues from the Gate of Vitality in Kidney Water, starting from the Three Yins to reach Shaoyang. If constrained by pathogens, it cannot reach Taiyang via Yangming. Pathogens lodging in the meridian cause alternating chills and fever, chest/hypochondriac fullness and hardness, vomiting, or thirst. With Liver and Gallbladder affected by pathogens, bitter taste, dry throat, and vertigo occur. Pathogens in Shaoyang press inward toward the Three Yins, making the path to the Exterior long; sweating would only damage Wei Qi and lose Yang Qi. Although Shaoyang is externally part of the Three Yangs, the path to the Interior is closer; purgation would only trap pathogens and damage the Stomach. Neither sweating nor purgation is suitable. Thus, Xiao Chai Hu Tang is established to ascend and disperse constrained Shaoyang pathogens, allowing Clear Yang to reach the Exterior and dissipate them, embodying the principle of "dispersing constrained Wood." Therefore, for the Shaoyang channel, this single formula is unique, with no other methods. Variations in symptoms merely involve modifications of this base formula. Once complications deviate from Shaoyang, Chai Hu is no longer appropriate, and other methods are employed. Even later formulas like Bu Zhong Yi Qi Tang and Xiao Yao San, which ascend Clear Yang and resolve constraint, adhere to the principles of Xiao Chai Hu Tang.
Chai Hu is the Sovereign herb. Li Shizhen stated: Chai Hu acts on the Hand and Foot Jueyin and Shaoyang meridians. For heat in the Spleen and Stomach or sinking of Yang Qi, Chai Hu is essential for guiding Clear Qi upward and reducing fever. Li Dongyuan said it guides Clear Qi to travel the Yang pathways; add it for febrile external conditions, omit if no fever. It also guides Stomach Qi upward, ascending like Spring energy. For various miasmas, Chai Hu is sovereign, combined with guide herbs according to the affected meridian. For sores and ulcers of the twelve meridians, it disperses blood stasis and qi stagnation. I interpret "Clear Qi" as the Clear Yang rising from the Lower Jiao. Called Clear Yang, it arises because turbid Qi from grains descends to the Lower Jiao, where it is steamed by the True Yang of the Gate of Vitality. Its Clear Qi rises, gathers in Danzhong to form the Sea of Qi, connects to the Lung for respiration, spreads to the skin as Wei Qi, circulates throughout the body as the Sanjiao, and attaches to the Liver and Gallbladder as Shaoyang Wind-Wood. If Clear Yang does not rise, internally it fails to generate Yang warmth, and externally it cannot expel pathogens. The *Yin Yang Ying Xiang Da Lun* states: "Clear Qi below generates diarrhea; Turbid Qi above generates distension." This reversal of Yin and Yang indicates pathological inversion. Hence, Li Dongyuan spoke of guiding Stomach Qi upward to act like Spring; Li Shizhen mentioned guiding Clear Qi to reduce fever for Spleen/Stomach heat and sinking Yang. If Lower Jiao True Yang is deficient, warming and tonifying the Gate of Vitality is primary. If it fails to ascend, urgently ascending Clear Yang is necessary. One must ensure Yang Qi circulates: Clear Yang exits through upper orifices, Turbid Yin through lower orifices; Clear Yang opens interstices, Turbid Yin enters the Five Zang; Clear Yang fills the four limbs, Turbid Yin returns to the Six Fu. Then Yin and Yang function correctly. Xiao Chai Hu Tang uses Chai Hu primarily to enable Clear Yang to open the interstices. Huang Qin assists Chai Hu to clear heat. The *Zang Qi Fa Shi Lun* states: "The Liver suffers from tension; eat sweet to relax it." Thus, Ren Shen and Gan Cao provide sweetness to relax. The Gallbladder is an Extraordinary Fu organ, storing pure juice without remainder, thus storing rather than transmitting, differing from other Fu organs. Shaoyang represents the beginning of Spring generation; when Spring Qi is vigorous, all things grow, so the eleven Zang-Fu depend on it. The Hand-Shaoyang Sanjiao functions via Qi; if Qi is weak, it cannot transport and transform. Thus, Ren Shen aids its ascending and circulating power.
The original formula includes modification rules based on symptoms. Modern practitioners often discard Ren Shen for safety, demonstrating ignorance of deficiency/excess dynamics. Ren Shen should only be removed if Heat is excessive and Pathogen is excess, or if concurrent symptoms contradict its use. If Pathogen is light but Righteous Qi is deficient, it should not be generally removed. Even if Pathogen is strong but Righteous Qi is severely deficient, removal must be considered carefully. For example, Chai Hu Gui Zhi Tang treats simultaneous Shaoyang and Taiyang syndromes (fever, slight aversion to cold, limb pain, slight vomiting, epigastric fullness). It uses half the dose of Xiao Chai Hu Tang plus half of Gui Zhi Tang to resolve both, retaining Ren Shen. Chai Hu Gui Zhi Gan Jiang Tang treats cases where sweating and purgation were erroneously used, resulting in chest/hypochondriac fullness with slight knotting, head sweat only, and alternating chills/fever. Here, Shaoyang and Taiyang pathogens remain unresolved. Gui Zhi, Gan Jiang, Gua Lou, and Mu Li are added, while Ren Shen, Ban Xia, Sheng Jiang, and Da Zao are removed. Chai Hu Jia Mang Xiao Tang addresses tidal fever and Stomach excess caused by inappropriate pill-based purgation leading to Shaoyang complication. Mang Xiao is added, but Ren Shen is retained because the core Shaoyang pattern persists. Da Chai Hu Tang treats a case where Taiyang pathology persisted over ten days after multiple erroneous purgations. After four to five days, if Shaoyang signs remain, Xiao Chai Hu Tang is given first. If vomiting persists, epigastric urgency increases, and depression/fretfulness continues, indicating pathogens entered the Interior from Taiyang due to error. Chai Hu resolves Shaoyang pathogens, while Da Huang and Zhi Shi purge Interior pathogens. Ren Shen is removed because the heat pathogen entering from Taiyang remains. These variations illustrate the flexibility of Xiao Chai Hu Tang. Essentially, if pathogens are solely in Shaoyang, Ren Shen is never removed. If accompanied by Taiyang Exterior signs or Yangming Stomach excess, Ren Shen is always removed. Mastering these principles allows for precise symptom-based modifications.
Ban Xia is pungent, warm, and slippery, resolving chest/hypochondriac fullness and hardness, akin to the logic of Ban Xia Xie Xin Tang, not merely treating phlegm-fluid retention. Sheng Jiang is pungent and dispersing; Da Zao is sweet and harmonizing, regulating Ying/Wei Qi and balancing alternating chills/fever. One formula covers one channel's syndromes; without flexible adaptation, its variations cannot be fully utilized.
Modifications:
If irritability in the chest without vomiting: Remove Ban Xia and Ren Shen; add one Gua Lou Shi (Trichosanthis Fructus).
Cold-damage constrained heat or Wind-strike Yang pathogens in the chest cause irritability. Shaoyang pathogens cause irritability; Taiyang pathogens in the chest also cause irritability due to heat binding in the chest. Tonifying Qi is inappropriate, so Ren Shen is removed. External pathogens invading the Stomach with cold-fluid accumulation cause vomiting; Ban Xia's pungent-warm-slippery nature dispels fluid. Without vomiting, pathogens have not invaded the Stomach, and fluids have not bound, so Ban Xia is removed. Gua Lou Shi is sweet, cold, and moistening, clearing fire and treating cough; it removes chest pathogens and stops irritability. Li Shizhen noted Zhang Zhongjing used Gua Lou Shi for chest bi pain radiating to the back, coughing/sputum, and jie xiong (chest binding) pain, leveraging its sweet-cold nature to protect Stomach Qi, descend Upper Jiao fire, and move phlegm downward. Cheng Wuji mistakenly called it bitter-cold to drain heat, likely due to unfamiliarity with its taste. Although both Gua Lou and Ban Xia are slippery, Gua Lou is sweet-cold (suitable for irritability/heat), while Ban Xia is pungent-warm (unsuitable here).
If thirst: Remove Ban Xia; increase Ren Shen to total 4.5 liang; add Gua Lou Gen (Trichosanthis Radix) 4 liang.
Ban Xia is pungent-spicy and warm, unsuitable for dry thirst. Gua Lou Gen is bitter-cold, clears heat, and generates fluids, making it suitable. Increasing Ren Shen boosts Qi to generate fluids.
If abdominal pain: Remove Huang Qin; add Bai Shao (Paeoniae Radix Alba) 3 liang.
Abdominal pain indicates Taiyin Spleen disease. Zhang Yuansu stated: White Peony tonifies, Red Peony disperses; both drain Liver and benefit Spleen/Stomach. Wine-soaked Peony moves meridians. For upper/middle abdominal pain, combine with Ginger to warm meridians, scatter dampness, and relieve pain. White Peony enters the Spleen meridian, tonifies the Middle Jiao, and is essential for dysentery, as dysentery is a Taiyin disease. Combined with Gan Cao, it treats abdominal pain; add slight Huang Qin for heat, Gui Zhi for cold. This is a divine formula of Zhang Zhongjing. Li Shizhen said White Peony benefits the Spleen and drains Wood from Earth; Red Peony disperses pathogens and moves blood stasis. Ri Hua Zi claimed Red Peony tonifies Qi and White Peony treats Blood, which is inaccurate. Danyang stated abdominal pain is mostly blood vessel coagulation, requiring wine-frying; however, limiting it only to blood-deficiency abdominal pain is not definitive. Since abdominal pain belongs to Taiyin, and Huang Qin is cold and damaging to the middle, it is removed. I believe Taiyin abdominal pain should be treated with warming herbs. If accompanied by Yangming Stomach excess (fullness and pain), Cheng Qi Tang is required, not treatable by Peony alone. If pain exists with unresolved Exterior pathogens, Peony is also contraindicated. Do not assume Peony is mandatory for all abdominal pain.
If hardness and stuffiness under the hypochondrium: Remove Da Zao; add Mu Li (Ostreae Concha) 4 liang.
The Shaoyang meridian descends through the chest, pierces the diaphragm, connects to the Liver and Gallbladder, and follows the hypochondrium. Pathogens invading the collaterals cause hypochondriac hardness/stuffiness. Da Zao is removed due to its sweet-harmonizing nature potentially exacerbating fullness. Cheng Wuji attributed Mu Li's use solely to its salty flavor softening hardness. Later commentators agreed. However, Zhang Zhongjing used it specifically for hypochondriac, not epigastric, hardness, indicating it pacifies Liver pathogens and enters Shaoyang collaterals, beyond just softening hardness. The *Shennong Ben Cao Jing* omits this; *Mingyi Bielu* mentions treating heart/hypochondriac heat. Wang Haogu noted: guided by Chai Hu, it removes hypochondriac hardness; by Tea, neck masses; by Da Huang, thigh swelling; by Di Huang, benefits essence and astringes urine. In Chai Hu Long Gu Mu Li Tang, it treats chest fullness, fright, and immobility, pacifying Wood and resolving Shaoyang pathogens, exceeding mere softening.
If palpitations in the epigastrium with difficulty urinating: Remove Huang Qin; add Fu Ling (Poria) 4 liang.
Palpitation refers to a trembling sensation. Locations vary: epigastric, cardiac, or umbilical. Cardiac palpitation with irritability relates to Xiao Jian Zhong Tang. Pulse knotted/intermittent with cardiac palpitation relates to Zhi Gan Cao Tang. Excessive sweating causing hand-over-heart palpitation relates to Gui Zhi Gan Cao Tang. Unresolved sweating with fever, epigastric palpitation, vertigo, tremors relates to Zhen Wu Tang. Post-sweating umbilical palpitation suggesting Ben Tun relates to Fu Ling Gui Zhi Gan Cao Da Zao Tang. These result from erroneous Taiyang treatments causing deficiency pathogens. Shaoyang Wind Strike causing deafness, red eyes, chest fullness/irritability also stems from deficiency post-emesis/purgation. Taiyang pulse thin/fine with headache/fever indicates Shaoyang; erroneous sweating causing Stomach disharmony and delirium requires Xiao Cheng Qi Tang. Though seeming like Stomach excess, it is actually Shaoyang pathogens exploiting sweating-induced deficiency to enter the Stomach, causing irritability/palpitation—a deficiency pathogen. Three Yin palpitations stem from Yin excess/Yang deficiency. Yangming has mostly excess pathogens, hence rarely palpitations. Only Taiyang cases with free urination drinking much water cause epigastric palpitation; scant urination causes lower urgency. This aligns with the current text: Taiyang heat not yet entering the Fu means Bladder has no heat, so urination is free. No internal heat leads to water-cold stagnation from excessive drinking, blocking Stomach Qi flow, causing epigastric palpitations. How much more so with difficult urination? Shaoyang is a hollow organ relying on Qi; pathogen invasion causes deficiency. Thus, Ren Shen in Xiao Chai Hu Tang tonifies. Even without excessive drinking, difficult urination implies Sanjiao failure to transport and Yang Qi failure to move, causing water-fluid stagnation in the Stomach and palpitations. Huang Qin is removed due to its cold nature damaging the middle. Fu Ling is added for its bland-draining property, moving upward and downward, promoting urination. If urination improves, palpitations cease. Removing cold Huang Qin and adding bland Fu Ling suggests Middle Jiao cold. If Lower Jiao Fire is absent and Qi transformation fails, and urination remains difficult, Wu Ling San might be considered.
If no thirst with slight external fever: Remove Ren Shen; add Gui Zhi (Cinnamomi Ramulus) 3 liang. Cover with blankets to induce slight sweating for cure.
No thirst indicates pathogens have not entered the Interior; slight external fever indicates the Exterior syndrome persists. Ren Shen is removed to avoid locking in Taiyang Exterior pathogens. The addition of Gui Zhi confirms Taiyang Exterior pathogens. Covering to induce slight sweating resolves Taiyang Wind pathogens. "Gui" here refers to Gui Zhi, not Rou Gui (Cinnamomi Cortex). Li Dongyuan stated: Thin flavor releases exterior (Gui Zhi ascends/reaches exterior); thick flavor generates heat (Rou Gui descends/nourishes Kidney). The text says "add Gui," implying Gui Zhi due to the sweating method. Transmission errors likely omitted "Zhi."
If coughing: Remove Ren Shen, Da Zao, Sheng Jiang; add Wu Wei Zi (Schisandrae Fructus) 0.5 sheng; Gan Jiang (Zingiberis Rhizoma) 2 liang.