蜀椒为足太阴及右肾气分之药。祛脾肾之寒湿而不治风寒风湿。若但寒无湿，亦有不宜。
治寒湿无分脾肾，而补火则独在肾。何以言之？性温燥而下行，足以祛寒湿而不足以祛风。
皮红膜白，间以黄肉，极里之子则黑，为由肺历脾入肾之象。故能使水中泛出之火，仍归水
中。热则肺病宜不相涉矣，而何以亦兼隶之。肺有寒饮无寒湿，寒饮之病，从不以椒治。但
寒之病，亦未尝以椒治。惟脾肾之寒湿上冲而为肺病挟火者，以椒引而下之，始为恰当。脾
肾病在本脏，肺病则由脾肾连及，所治虽同而本末攸异。此愚所以不以手太阴药并提之也。
椒既由肺抵肾，势不中停，自当以温肾为首功。故他物温脾寒除脾湿，效惟在脾而已；
椒则归宿在肾，不第供职于脾。虽然脾居中宫，不能飞渡。有肾病脾不病而可以椒治者乎，
则试取仲圣方核之∶乌头赤石脂丸，邪在上焦，而用乌附干姜石脂中下焦之药，非脾肾有寒
湿不尔；更佐以蜀椒，非引火下归不尔。白术散，尤氏谓治寒湿之剂，术芎与椒牡并施，意
自在于温下。他如大建中汤、乌梅丸，一为呕痛腹满，一为蛔厥呕烦。皆病在脾肾而阴中有
阳，而其用蜀椒也，又岂有二道哉。
吴茱萸树高丈余，皮青绿色，实结梢头，其气燥，故得木气多而用在于肝。叶紫花紫实
紫，紫乃水火相乱之色。实熟于秋季，气味苦辛而温，性且烈，是于水火相乱之中，操转旋
拨反之权，故能入肝伸阳戢阴而辟寒邪。味辛则升，苦则降；辛能散，苦能坚；亦升亦降，
亦散亦坚；故上不至极上，下不至极下，第为辟肝中之寒邪而已。
呕吐有寒有热，不因少阳干胃，即属厥阴干胃。少阳干胃，则如心烦喜呕与呕而发热皆
是；厥阴干胃，则如呕而胸满、与干呕吐涎沫、头痛皆是。仲圣小柴胡汤、吴茱萸汤分主甚
明。虽然有呕吐主以吴茱萸汤，而曰阳明病少阴病者，人必谓于厥阴无与矣，而不知实厥阴
病之见于阳明少阴也。何以言之？食谷欲呕者，肝受寒邪，上攻其胃。不食谷则肝气犹舒，
食谷则肝不能容而欲呕。与胃虚之有胃反迥殊，故非吴茱萸汤不治。夫肝邪上攻则胃病，为
木乘土。下迫则肾病，为子传母。迨子传母，则吐利交作而不止一吐矣。少阴自病，下利已
耳，未必兼吐；吐而利矣，未必兼逆冷烦躁；吐利而且手足逆冷烦躁欲死，非肝邪盛极而何。
此
愚既以吴茱萸为肝药。夫血藏于肝，温肝自当温血；而不知吴茱萸能散血中之气寒，非
能温血中之血寒也。厥阴病至于吐利、手足逆冷、烦躁欲死，若是血病，何得无当归。当归
四逆汤脉细欲绝，血寒之证也，何以反无吴茱萸，及知有久寒而后加之。即其非胃药肾药亦
有可证者，在阳明乃两阳合明，寒不易受，仲圣言胃中虚冷者不一，无用吴茱萸之方。纵云
吴茱萸兼治胃寒，夫岂不闻干呕吐涎沫头痛之厥阴病非吴茱萸不治乎。吴茱萸既为肝寒要药，
以移治胃寒肝不寒之病，宁能无误。故仲圣恐人误用，又申之曰得汤反剧者属上焦。然则治
上焦之药何在？半夏干姜散，正治干呕吐逆吐涎沫之胃寒也。他如甘草泻心汤、黄连汤，中
有干姜，亦所以治胃寒。愚于此又悟干姜吴茱萸，与黄连黄芩为对待矣。本经黄连主肠 腹
痛，黄芩主肠 不主腹痛。故小柴胡汤腹痛去黄芩，而黄连汤腹痛则用黄连，同一寒药，不
能通用如是。岂有同一热药，可漫无区别。愚不以吴茱萸为肾药者，盖亦以别有肾药，与吴
茱萸分疆而治者也。温肾者为附子，温脾者为干姜。太阴藏寒曰宜四逆辈，以四逆汤非温脾
之正方也，温脾正方为理中丸。理中丸固有干姜无附子，而四逆汤治肾有附子又有干姜，则
又何也？盖肾寒必上侮其脾，干姜在脾为中权，在肾为前茅，故姜附不可缺一，吴茱萸岂其
比乎。夫肾脏者真阳所寓，有扶阳以抑阴，无辟阴以伤阳。吴茱萸得厕名于少阴者，非能治
肾寒也，治肝寒之流及于肾者也。就是数者反复核之，尚何疑吴茱萸之非血药、非胃药、非
肾药哉。
温经汤有瘀血在少腹，而以吴茱萸为君，非以其能行瘀也。妇人年五十所而病非新得，
宜缓图不宜峻攻。故不用下瘀血汤抵当汤，而以桂枝芍药丹皮三味行瘀。即以三味协参草芎
归胶麦姜夏，补中调气，和血濡燥。为之绸缪者，已无微不至矣。更何需苦温辛烈之吴茱萸
哉。不知妇人之病，多因虚积冷结气，瘀血在少腹不去，其为有久寒可知。冲任之血，肝实
主之。肝中积结之气，非吴茱萸讵能辟去。此实是证之枢纽，曰温经者，纪其实也。
吴茱萸上不至极上，下不至极下。然吴茱萸汤之厥阴头痛，温经汤之瘀血在少腹，何非
极上极下，要皆为辟肝寒之效所及，非能径抵头与少腹也。由是推之，吴茱萸之用，亦綦广
矣。胃主降，脾主升，脾之所以升，实得风木制化之益，故肝病者脾必病，吴茱萸能入肝驱
邪，化阴凝为阳和，脾何能不温，腹痛腹胀何能不治。其性苦过于辛，降多而升少，肝主疏
泄，肝平则气自下，此所以又利大肠壅气治滞下也。
抑有用之为反佐者，古方左金丸，治肝脏火实左胁作痛，似非吴茱萸热药所宜。顾其方
黄连多于吴茱萸五倍，肝实非吴茱萸不泄，连多茱少，则不至助热，且足以解郁滞之热，肝
脾两获其益。故腹痛用之，亦每有神验。活法在人，未可为胶柱鼓瑟者道也。
蜀椒是作用于足太阴脾经及右肾气分的药物。它能祛除脾肾的寒湿，但不能治疗风寒或风湿之邪。如果只有寒邪而没有湿邪，也不适宜使用。
它治疗寒湿不分脾与肾，但在补火方面则专门针对肾脏。为什么这样说呢？因为它的性质温燥且药势下行，足以祛除寒湿却不足以祛除风邪。
蜀椒外皮红色、内膜白色，中间夹杂着黄色的果肉，极里面的种子则是黑色的，这象征着药力由肺经过脾最终进入肾。因此，它能使水中泛溢之火重新回归水中。既然热证属于肺病应当与此无关，那为什么它也归属于肺经呢？这是因为肺中有寒饮而无寒湿，寒饮的病从不以蜀椒治疗；单纯的寒证，也未曾用蜀椒治疗。只有当脾肾的寒湿之气上冲导致肺部病变并夹杂火邪时，用蜀椒将其引向下行，才算是恰当的治疗。脾和肾的病变在本脏，而肺的病变是由脾肾牵连所致，虽然治疗的药物相同，但本末关系截然不同。这就是我之所以不将蜀椒列为手太阴肺经药物的原因。
蜀椒既然从肺直达肾脏，药势中途不停留，自然应当以温补肾阳为首要功效。所以其他药物温脾后寒除脾湿，疗效仅局限于脾；而蜀椒归宿在肾，不仅仅服务于脾。虽然脾居中宫（中焦），不能自行飞渡至下焦。那么有没有肾病而脾不病，却可以用蜀椒治疗的例子呢？我们可以参考张仲景的方剂来验证：乌头赤石脂丸，病邪在上焦，却使用了乌头、附子、干姜、赤石脂等作用于中下焦的药物，如果不是脾肾有寒湿就不会这样用药；再辅以蜀椒，不是为了引火下行归位不会这样配伍。白术散，尤氏认为是治疗寒湿的方剂，白术、川芎与蜀椒、牡蛎并用，用意自然在于温补下焦。其他的如大建中汤、乌梅丸，一个治疗呕吐疼痛腹部胀满，一个治疗蛔厥引起的呕吐烦躁。这些病症都在脾肾，且阴中有阳，它们使用蜀椒的道理，难道会有两样吗？
吴茱萸树高丈余，树皮青绿色，果实结在梢头，气味燥烈，因此得木气较多，作用在于肝脏。叶子紫色、花紫色、果实紫色，紫色是水与火相混杂的颜色。果实成熟于秋季，气味苦辛而温，药性猛烈，这是在水火相乱之中，掌握着转旋拨反的权柄，因此能入肝伸展阳气、收敛阴气从而驱散寒邪。味辛则上升，味苦则下降；辛能发散，苦能坚阴；既升又降，既散又坚；因此它向上不到极上，向下不到极下，只是用来驱散肝脏中的寒邪罢了。
呕吐有寒证和热证之分，如果不是少阳胆经干扰胃腑，就是厥阴肝经干扰胃腑。少阳干扰胃腑，就会出现心烦喜呕以及呕吐伴发热等症状；厥阴干扰胃腑，就会出现呕吐伴胸满、干呕吐涎沫、头痛等症状。张仲景的小柴胡汤和吴茱萸汤分别主治这两种情况，区分得很明确。虽然有呕吐主要用吴茱萸汤治疗，但条文提到“阳明病”、“少阴病”时，人们必定认为这与厥阴无关，却不知道这实际上是厥阴病的症状表现于阳明和少阴经。为什么这样说呢？进食就想呕吐的，是肝受寒邪，向上攻冲胃腑。不吃东西时肝气尚且舒展，吃东西时肝不能容纳而想要呕吐。这与胃虚导致的胃反病完全不同，所以非吴茱萸汤不能治愈。肝邪向上攻冲则导致胃病，这是木乘土（肝木克脾土）；向下逼迫则导致肾病，这是子传母（肝为心之母，此处指肝肾同源或母子相生关系，原文意指肝病及肾）。等到子传母阶段，就会吐利交作而不止于呕吐。少阴自病，只是下利而已，未必兼有呕吐；既有呕吐又有下利，未必兼有手足逆冷烦躁；如果吐利而且手足逆冷、烦躁欲死，这不是肝邪盛极到了什么程度呢？
我既然认定吴茱萸是治肝的药。血藏于肝，温肝自然应当温血；但不知道吴茱萸能散血中之气的寒，并不能温血中之血的寒。厥阴病发展到吐利、手足逆冷、烦躁欲死的程度，如果是血分病，怎么会没有当归呢？当归四逆汤脉细欲绝，是血寒的证候，为什么反而没有吴茱萸，而是等到有久寒时才加入？由此也可以证明它不是治胃和肾的药。在阳明经，因为是两阳合明，寒邪不易侵入，张仲景说胃中虚冷的情况有很多，却没有使用吴茱萸的方子。纵然说吴茱萸兼治胃寒，难道没听说过干呕吐涎沫头痛的厥阴病非吴茱萸不治吗？吴茱萸既然是治疗肝寒的要药，拿来治疗胃寒而肝不寒的病，怎么能不出错呢？所以张仲景恐怕人误用，又补充说“服药后反应加剧的，病位在上焦”。那么治疗上焦的药在哪里呢？半夏干姜散，正是治疗干呕吐逆吐涎沫的胃寒证。其他的如甘草泻心汤、黄连汤，其中含有干姜，也是用来治疗胃寒的。我于此又领悟到干姜、吴茱萸，与黄连、黄芩是对待的关系。《本经》记载黄连主肠腹痛，黄芩主肠但不主腹痛。所以小柴胡汤证见腹痛要去掉黄芩，而黄连汤证见腹痛则用黄连，同样是寒药，不能通用到如此地步。难道同为热药，就可以漫无区别吗？我不把吴茱萸当作肾药，大概是因为另有治肾的药，与吴茱萸界限分明各自治疗。温肾的是附子，温脾的是干姜。太阴脏寒说适宜用四逆汤之类的药，因为四逆汤并非温脾的正方形药，温脾的正方形药是理中丸。理中丸固有干姜而无附子，而四逆汤治肾有附子又有干姜，那又是为什么呢？因为肾寒必然会上侮其脾，干姜在脾是中流砥柱，在肾是先锋部队，所以姜和附子不可缺一，吴茱萸岂能相比呢？肾脏是真阳所寓居的地方，只有扶助阳气以抑制阴邪，没有驱散阴邪而损伤阳气的道理。吴茱萸被列入少阴经药，并不是能治肾寒，而是治疗肝寒波及到肾的情况。综合上述几点反复核实，还有什么怀疑吴茱萸不是血药、不是胃药、不是肾药的呢？
温经汤中有瘀血在少腹，而以吴茱萸为君药，并不是因为它能行瘀。妇人年五十岁左右患病并非新近所得，应该缓慢图谋不宜峻猛攻伐。所以不用下瘀血汤或抵当汤，而用桂枝、芍药、丹皮三味药来行瘀。再用这三味药配合人参、甘草、川芎、当归、阿胶、麦冬、生姜、半夏，补益中气调理气机，调和血液滋润干燥。为之做的周密准备已经无微不至了。哪里还需要苦温辛烈的吴茱萸呢？不知道妇人的病，多因虚积冷结气，瘀血在少腹不去，这说明是有久寒。冲任之血，主要由肝主宰。肝中积结的气，如果不是吴茱萸谁能驱散？这确实是这个证候的关键所在，称为“温经”，是记录其实质。
吴茱萸向上不到极上，向下不到极下。然而吴茱萸汤治疗的厥阴头痛，温经汤治疗的少腹瘀血，何尝不是极上极下？但这都是驱散肝寒的功效所及，并不是能直接抵达头部和少腹。由此推论，吴茱萸的用途也很广泛。胃主降，脾主升，脾之所以能升，实际上得益于风木（肝）的制约和化育，所以肝病者脾必病，吴茱萸能入肝驱邪，将阴凝化为阳和，脾怎么能不温暖，腹痛腹胀怎么能不治愈。吴茱萸的性质苦过于辛，降多而升少，肝主疏泄，肝气平和则气自然下行，这就是它又能利于大肠壅气、治疗滞下的原因。
还有将其作为反佐药使用的，古方左金丸，治疗肝脏火实导致的左胁作痛，似乎不适合吴茱萸这种热药。但是该方中黄连多于吴茱萸五倍，肝实非吴茱萸不能疏泄，黄连多吴茱萸少，则不至于助热，且足以解除郁滞之热，肝脾两获其益。所以腹痛用它，也每每有神效。活法在人，不可以胶柱鼓瑟地谈论。
Shu Jiao (Sichuan Pepper) is a herb acting on the Foot-Taiyin Spleen channel and the Qi aspect of the Right Kidney. It dispels Cold-Dampness from the Spleen and Kidney but does not treat Wind-Cold or Wind-Dampness. If there is only Cold without Dampness, it is also unsuitable.
It treats Cold-Dampness regardless of whether it involves the Spleen or Kidney, but in tonifying Fire, it focuses exclusively on the Kidney. Why is this? Its nature is Warm and Dry, and its action moves downward; it is sufficient to dispel Cold-Dampness but insufficient to dispel Wind.
The skin is red, the inner membrane white, with yellow flesh in between, and the seeds at the very center are black. This represents the image of the medicinal power traveling from the Lung, through the Spleen, to enter the Kidney. Therefore, it can cause the Fire floating up from the Water to return to the Water. Since Heat syndromes involve Lung pathology and should be unrelated, why is it also attributed to the Lung? This is because when there is Cold-Fluid in the Lung without Cold-Dampness, Shu Jiao is never used to treat Cold-Fluid diseases; nor is it used for pure Cold diseases. Only when Cold-Dampness from the Spleen and Kidney rushes upward causing Lung pathology accompanied by Fire is using Shu Jiao to guide it downward appropriate. The pathology of the Spleen and Kidney resides in their own Zang organs, whereas Lung pathology is connected via the Spleen and Kidney. Although the treated herbs are the same, the root and branch differ significantly. This is why I do not list it alongside Hand-Taiyin Lung herbs.
Since Shu Jiao travels from the Lung directly to the Kidney without stopping midway, its primary merit must be warming the Kidney. Thus, other herbs that warm the Spleen and remove Spleen-Dampness have effects limited to the Spleen; Shu Jiao returns to the Kidney and serves not only the Spleen. Although the Spleen resides in the Central Palace (Middle Jiao) and cannot fly across, are there cases where the Kidney is diseased but the Spleen is not, yet can be treated with Shu Jiao? Let us examine the formulas of Zhang Zhongjing: Wu Tou Chi Shi Zhi Wan (Aconite and Red Earth Pill), where the pathogen is in the Upper Jiao, yet Aconite, Fuzi, Gan Jiang, and Chi Shi Zhi—herbs acting on the Middle and Lower Jiao—are used. This would not be done unless there was Cold-Dampness in the Spleen and Kidney; adding Shu Jiao is specifically to guide the Fire back down. Bai Zhu San, which You Shi considered a formula for Cold-Dampness, combines Bai Zhu and Xiong Chu with Shu Jiao and Mu Li, intending to warm the Lower Jiao. Similarly, Da Jian Zhong Tang and Wu Mei Wan treat vomiting, pain, abdominal fullness, and ascariasis jue with vomiting and irritability. In all these cases, the disease lies in the Spleen and Kidney, with Yang hidden within Yin, and the use of Shu Jiao follows the same principle.
Wu Zhu Yu (Evodia Fruit) trees grow over one zhang high, with greenish-blue bark, and fruits borne at the tips. Its odor is dry and pungent, so it acquires much Wood Qi and its action lies in the Liver. The leaves, flowers, and fruits are all purple; purple is the color of Water and Fire mixed. The fruit ripens in autumn, with a bitter, pungent, and warm taste, and a fierce nature. Within the chaos of mixed Water and Fire, it holds the power to reverse and rotate, thus entering the Liver to extend Yang, subdue Yin, and repel Cold pathogens. Pungency causes ascending, bitterness causes descending; pungency disperses, bitterness consolidates; it both ascends and descends, both disperses and consolidates. Therefore, it does not reach the extreme upper or lower, but merely repels Cold pathogens in the Liver.
Vomiting can be Cold or Hot. If not caused by Shaoyang interfering with the Stomach, it belongs to Jueyin interfering with the Stomach. Shaoyang interference presents as heart vexation, desire to vomit, and vomiting with fever. Jueyin interference presents as vomiting with chest fullness, dry heaving with salivary foam, and headache. Zhang Zhongjing’s Xiao Chai Hu Tang and Wu Zhu Yu Tang clearly distinguish these treatments. Although vomiting is primarily treated with Wu Zhu Yu Tang, mentions of "Yangming Disease" and "Shaoyin Disease" lead people to believe they are unrelated to Jueyin, not realizing they are actually Jueyin manifestations appearing in Yangming and Shaoyin. Why? "Desire to vomit after eating food" indicates the Liver has received Cold pathogens and attacks the Stomach upwards. Without food, Liver Qi is relatively free; with food, the Liver cannot accommodate it and desires to vomit. This is distinct from Wei Fan (Stomantic Reversal) due to Stomach deficiency, hence requiring Wu Zhu Yu Tang. When Liver pathogens attack upwards, they damage the Stomach (Wood overacting on Earth); when pressing downwards, they damage the Kidney (Child transmitting to Mother). Once Child transmits to Mother, vomiting and diarrhea occur together, not just vomiting alone. Shaoyin self-disease involves only diarrhea, not necessarily vomiting; if vomiting and diarrhea coexist, cold limbs and irritability may not accompany them; but if vomiting and diarrhea are accompanied by cold limbs and extreme irritability, this must be due to extreme excess of Liver pathogens.
I assert Wu Zhu Yu is a Liver herb. Blood is stored in the Liver, so warming the Liver should warm the Blood; however, Wu Zhu Yu disperses Cold in the Qi of the Blood, it does not warm Cold in the Blood itself. In Jueyin disease progressing to vomiting, diarrhea, cold limbs, and extreme irritability, if this were a Blood disease, why is Dang Gui absent? Dang Gui Si Ni Tang, with a pulse fine and nearly imperceptible, treats Blood Cold; why is Wu Zhu Yu absent initially and added only later for chronic Cold? This proves it is not a Stomach or Kidney herb. In Yangming, being the convergence of two Yangs, Cold is hard to invade. Zhang Zhongjing frequently mentions Empty-Cold in the Stomach but provides no formulas using Wu Zhu Yu. Even if one claims Wu Zhu Yu treats Stomach Cold, does one not know that Jueyin disease with dry heaving, salivary foam, and headache requires Wu Zhu Yu? As the key herb for Liver Cold, using it for Stomach Cold without Liver Cold will surely cause errors. Thus, Zhang Zhongjing warned against misuse, stating "if symptoms worsen after taking the decoction, the disease is in the Upper Jiao." So where is the herb for the Upper Jiao? Ban Xia Gan Jiang San treats Stomach Cold with dry heaving and salivary foam. Other formulas like Gan Cao Xie Xin Tang and Huang Lian Tang contain Gan Jiang to treat Stomach Cold. I realize here that Gan Jiang and Wu Zhu Yu correspond to Huang Lian and Huang Qin. The Ben Jing states Huang Lian treats intestinal abdominal pain, while Huang Qin treats intestinal issues but not abdominal pain. Hence, in Xiao Chai Hu Tang, Huang Qin is removed for abdominal pain, but in Huang Lian Tang, Huang Lian is used for abdominal pain. Same Cold herbs cannot be used interchangeably. How can same Heat herbs be used indiscriminately? I do not consider Wu Zhu Yu a Kidney herb because there are specific Kidney herbs that govern different territories. Fu Zi warms the Kidney, Gan Jiang warms the Spleen. For Taiyin Zang Cold, Si Ni Tang is suggested, but Si Ni Tang is not the primary formula for warming the Spleen; Li Zhong Wan is. Li Zhong Wan contains Gan Jiang but no Fu Zi. Si Ni Tang for Kidney Cold contains both. Why? Because Kidney Cold inevitably insults the Spleen; Gan Jiang acts as the central authority in the Spleen and the vanguard in the Kidney, so Ginger and Aconite cannot be missing. Wu Zhu Yu cannot compare. The Kidney houses True Yang; there is supporting Yang to suppress Yin, but no repelling Yin to damage Yang. Wu Zhu Yu is listed under Shaoyin not to treat Kidney Cold, but to treat Liver Cold spreading to the Kidney. Reviewing these points, what doubt remains that Wu Zhu Yu is not a Blood, Stomach, or Kidney herb?
Wen Jing Tang contains Blood Stasis in the Lower Abdomen, using Wu Zhu Yu as the Sovereign herb, not because it moves stasis. Women around fifty suffering from non-acute conditions require slow treatment, not aggressive purging. Thus, Xia Yu Xue Tang or Di Dang Tang are avoided; instead, Gui Zhi, Bai Shao, and Dan Pi move stasis gently. Combined with Ren Shen, Gan Cao, Chuan Xiong, Dang Gui, E Jiao, Mai Dong, Sheng Jiang, and Ban Xia, they tonify the Center, regulate Qi, harmonize Blood, and moisten dryness. Preparations are meticulous. Why then need the bitter-warm and pungent-fierce Wu Zhu Yu? One must understand that women's diseases often stem from deficiency, accumulated Cold, and stagnant Qi. Blood stasis remaining in the Lower Abdomen indicates chronic Cold. Chong and Ren vessel Blood are governed by the Liver. Stagnant Qi in the Liver cannot be dispelled except by Wu Zhu Yu. This is the pivot of the syndrome; "Warming the Menses" records its essence.
Wu Zhu Yu does not reach the extreme upper or lower. Yet, Jueyin headache treated by Wu Zhu Yu Tang and Blood Stasis in the Lower Abdomen treated by Wen Jing Tang seem extreme. However, these are effects of repelling Liver Cold, not direct action on the head or lower abdomen. By extension, the uses of Wu Zhu Yu are extensive. The Stomach governs descending, the Spleen governs ascending. The Spleen's ability to ascend benefits from the control and transformation of Wind-Wood (Liver). Thus, Liver disease affects the Spleen. Wu Zhu Yu enters the Liver to drive out pathogens, transforming Yin stagnation into Yang harmony. How can the Spleen remain unwarmed, and abdominal pain/bloating remain untreated? Its nature is more bitter than pungent, with more descending than ascending. The Liver governs dispersion and drainage; when Liver Qi is peaceful, it flows downward naturally. This is why it also benefits Large Intestine obstruction and treats dysentery-like stagnation.
There is also its use as an adjuvant (Fan Zuo). The ancient formula Zuo Jin Wan treats Liver Fire excess causing left hypochondriac pain, seemingly unsuitable for the hot Wu Zhu Yu. However, in this formula, Huang Lian exceeds Wu Zhu Yu by five times. Liver excess requires Wu Zhu Yu for dispersion; with more Huang Lian and less Wu Zhu Yu, it does not aid Heat but resolves stagnant Heat, benefiting both Liver and Spleen. Thus, it is effective for abdominal pain. Clinical application varies; one cannot be rigid.