少阳主春，其气半出地外，半在地中，人身之气亦如之，故主半表半里也。半表者，谓在外之太阳也；半
里者，谓在内之太阴也。邪入其间，阴阳相移，寒热交作，邪正相持，进退互拒，此际汗、吐、下三法俱在所
禁，故立小柴胡汤和解法，加减施治。然小柴胡加减法中，又有口不渴身有微热者，加桂枝以取汗，及下后胸
胁满微结，小便不利，渴而不呕，头汗出，往来寒热者，用柴胡桂枝干姜汤汗之。又有柴胡证具，而反下之，
心下满而硬痛者，此为结胸也，大陷胸汤主之；及柴胡证仍在者，先与小柴胡汤。呕不止心下急，郁郁微烦者，
为未解也，与大柴胡汤下之。更有本柴胡证，医以丸药，下之微利，胸胁满而呕，日晡潮热者，小柴胡加芒硝
汤下之等法。是仲景亦有汗、下之法，惟在临证详察，因病施治，不可执一也。
少阳之为病，口苦，咽干，目眩也。
【注】少阳者，胆经也。其脉起于目锐 ，从耳后入耳中，挟咽出颐颔中。邪伤其经，故口苦、咽干、
目眩也，口苦者，热蒸胆气上溢也；咽干者，热耗其津液也；目眩者，热熏眼发黑也。此揭中风、伤寒邪传少
阳之总纲，凡篇中称少阳中风、伤寒者，即具此证之谓也。
【集注】林澜曰∶论中言少阳病，胸胁痛耳聋，往来寒热，心烦喜呕，胸胁痞硬，半表半里之证详矣。
此何以曰口苦咽干目眩也？大抵病于经络者，此篇诸条已悉之矣，若胆热腑自病，则又必有此证也。
沈明宗曰∶此虽少阳总证，然偏里矣。少阳主胆，其脉循胁络于耳，故胸胁痛而耳聋。仲景另出手眼，
以补口苦、咽干、目眩之里证，乃括少阳风伤卫、寒伤荣，风寒两伤而言也。
吴人驹曰∶少阳者，一阳也。少阳之上，相火主之。若从火化，火盛则干，故口苦咽干也。少阳属木，木
主肝，肝主目，故病则目眩也。
魏荔彤曰∶胆腑与少阳经为表里，而非半表半里之谓。半表者，对太阳之全表言；半里者，对太阴之全里
言。故少阳在半表半里之间，总以经络之界为言。又曰∶经中所谓不必悉具者，指或中余证，而少阳经胆腑之
主病，未有不悉具而遽可指为少阳病成者。
少阳中风，两耳无所闻，目赤，胸中满而烦者，不可吐下，吐下则悸而惊。
【注】少阳，即首条口苦、咽干、目眩之谓也。中风，谓此少阳病，是从中风之邪传来也。少阳之脉，起
目锐 ，从耳后入耳中；其支者，会缺盆，下胸中，循胁。表邪传其经，故目赤耳聋，胸中满而烦也。然此乃
少阳半表半里之胸满而烦，非太阳证具之邪陷胸满而烦者比，故不可吐、下，若吐、下则虚其中，神志虚怯，
则悸而惊也。此揭中风邪传少阳之大纲也。
【集注】程知曰∶少阳惟宜和解，若吐之则虚其阳而悸，下之则虚其阴而惊。
汪琥曰∶少阳有吐下之禁，只因烦满，故误行吐下之法。成注谓∶吐则伤气，气虚者悸；下则亡血，血虚
者惊。不知惊悸，皆主于心，误吐且下，则津液衰耗，神志虚怯，故
悸而惊也
沈明宗曰∶胸中烦满似乎可吐，但在少阳，其邪已下胸循胁，吐之徒伤胸中之气，使邪内并逼迫神明，则
悸而惊也。
魏荔彤曰∶此条论仲景不出方。小柴胡条中有心烦心下悸之证，想可无事他求也。汗、吐、下三法既不可
行，则当和解之。小柴胡为少阳对证之药，斯用之宜决耳！
伤寒，脉弦细，头痛发热者，属少阳。少阳不可发汗，发汗则谵语。此属胃，胃和则愈，胃不和，则烦而悸。
【注】不曰少阳伤寒，而曰伤寒，略言之也。谓此少阳病是从伤寒之邪传来也。脉弦细，少阳之脉也。上
条不言脉，此言脉者，补言之也。头痛发热无汗，伤寒之证也，又兼见口苦、咽干、目眩少阳之证，故曰属少
阳也。盖少阳之病已属半里，故不可发汗，若发汗，则益伤其津，而助其热，必发谵语，既发谵语，则是转属
胃矣。若其人津液素充，胃能自和，则或可愈；否则津干热结，胃不能和，不但谵语，且更烦而悸矣。此揭伤
寒邪传少阳之大纲也。
【集注】王肯堂曰∶凡头痛、发热俱为在表，惟此头痛、发热为少阳者何也？以其脉弦细，故知邪入少阳
之界也。
喻昌曰∶少阳伤寒禁发汗，少阳中风禁吐、下，二义互举，其旨益严。盖伤寒之头痛发热，宜于发汗者，
尚不可汗，则伤风之不可汗，更不待言矣。伤风之胸满而烦，似可吐、下者，尚不可吐、下，则伤寒之不可吐、
下，更不待言矣。脉弦细者，邪欲入里，其在胃之津液已为热耗，重复发汗，而驱其津液外出，安得不谵语乎？
汪琥曰∶误发其汗，谵语者，夺其津液而胃干，故言乱也。此少阳之邪，已转属胃。胃和则愈者，言当
用药以下胃中之热，而使之和平也。胃不和，不但谵语，更加烦扰忪悸，此言胃热上犯于心，故藏神不自宁也。
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。
【注】此承上三条，互详其证，以明其治也。伤寒中风三四日，见口苦、咽干、目眩之证，与弦细之脉，
知邪已传少阳矣。若兼见耳聋目赤，胸满而烦者，则知是从中风传来也；若兼见头痛发热无汗者，则知是从伤
寒传来也。今五六日，更见往来寒热，胸胁苦满，默默不欲饮食，心烦喜呕，则知是中风、伤寒兼见俱有之证
也。少阳之邪，进可传太阴之里，退可还太阳之表，中处于半表半里之间。其邪外并于表，半表不解则作寒，
内并于里，半里不和则作热；或表或里无常，故往来寒热不定也。少阳之脉，下胸循胁，邪凑其经，故胸胁苦
满也；少阳邪近乎阴，故默默也；少阳木邪病则妨土，故不欲饮食也；邪在胸胁，火无从泄，上逼于心，故心
烦也；邪欲入里，里气外拒，故呕；呕则木气舒，故喜之也。此皆柴胡应有之证也。其余诸证，时或有之，总
宜以小柴胡汤主之，各随见证以加减治之可耳！然既分中风、伤寒之传，而不分其治者何也？盖以太阳有营卫
之分，故风寒之辨宜严，及传阳明、少阳则无营卫之分，且其邪皆化热，故同归一致也。
【集注】成无己曰∶邪在表里之间，谓之半表半里。伤寒中风者，是或伤寒或中风，非伤寒再中风，中风
复伤寒也。五六日，邪自表传里之时，邪在表则寒，在里则热，今在半表半里之间，未有定处，故往来寒热也。
邪在表心腹不满，邪在里则心腹胀满，今言胸胁苦满，亦是在表里之间也。邪在表呻吟不安，邪在里则内烦。
经云∶阳入之阴，则静默默，由邪方自表之里，在表里之间也。邪在表则能食，邪在里不能食，不欲食者，未
至于必不能食，故亦为在表里之间也。邪在
表则不烦、不呕，邪在里则烦满而呕，烦而喜呕者，邪在表方传里也。邪初入里，未有定处，所传不一，故有
或见之证也。
方有执曰∶五六日，大约言也。往来寒热者，邪入躯壳之里，脏腑之外，两界之隙地，所谓半表半里，乃
少阳所主之部位也。故入而并于阴则寒，出而并于阳则热，出入无常，故寒热间作也。太阳一经，有营卫之不
同，所以风寒异治；阳明切近太阳，营卫之道在迩，风寒之辨尚严；少阳一经，越阳明去太阳远矣，风寒无异
治。经以伤寒、中风五六日，往来寒热，交互为文者，发明风寒至此，同归于一致也。
小柴胡汤方
柴胡（半斤） 黄芩（三两） 人参（三两） 半夏（洗，半升） 甘草（炙，三两） 生姜（切，三两） 大
枣（擘，十二枚）
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。
加减法∶若胸中烦而不呕，去半夏、人参，加栝蒌实一枚。若渴，去半夏，加人参合前成四两半，栝蒌根
四两。若腹中痛者，去黄芩加芍药三两。若胁下痞硬，去大枣加牡蛎四两。若心下悸，小便不利者，去黄芩加
茯苓四两。若不渴，外有微热者，去人参加桂枝三两，温服微汗愈。若咳者，去人参、大枣、生姜，加五味子
半升，干姜二两。
【方解】邪传太阳、阳明，曰汗、曰吐、曰下，邪传少阳惟宜和解，汗、吐、下三法皆在所禁，以其邪在
半表半里，而角于躯壳之内界。在半表者，是客邪为病也；在半里者，是主气受病也。邪正在两界之间，各无
进退而相持，故立和解一法，既以柴胡解少阳在经之表寒，黄芩解少阳在腑之里热，犹恐在里之太阴，正气一
虚，在经之少阳，邪气乘之，故以姜、枣、人参和中而预壮里气，使里不受邪而和，还表以作解也。世俗不审
邪之所据，果在半表半里之间，与所以应否和解之宜，及阴阳疑似之辨，总以小柴胡为套剂。医家幸其自处无
过，病者喜其药味平和，殊不知因循误人，实为不浅。故凡治病者，当识其未然，图机于早也。
【集解】程应旄曰∶方以小柴胡名者，取配乎少阳之义也。至于制方之旨及加减法，则所云上焦得通，津
液得下，胃气因和尽之矣。方中以柴胡疏木，使半表之邪得从外宣；黄芩清火，使半里之邪得从内彻；半夏豁
痰饮，降里气之逆，人参补内虚，助生发之气；甘草佐柴、芩，调和内外；姜、枣佐参、夏，通达营卫。相须
相济，使邪不至内向而外解也。至若烦而不呕者，火气燥实逼胸也，故去人参、半夏，加栝蒌实也。渴者，燥
已耗液逼肺也，故去半夏加栝蒌根也。腹中痛者，木气散入土中，胃阳受困，故去黄芩以安土，加芍药以戢木
也。胁下痞硬者，邪既留则木气实，故去大枣之甘而缓，加牡蛎之咸而软也。心下悸，小便不利者，水邪侵乎
心，故去黄芩之苦寒，加茯苓之淡渗也，不渴身有微热者，半表之寒，尚滞于肌，故去人参加桂枝以解之也。
咳者，半表之寒，凑入于肺，故去参、枣，加五味子，易生姜为干姜以温之，虽肺寒不减黄芩，恐干姜助热也。
总之邪在少阳，是半表半里之热，郁而不升，故以小柴胡治之，所谓升、降、浮、沉则顺之也。
伤寒中风，有柴胡证，但见一证便是，不必悉具。
【注】此承上而言，无论伤寒中风，邪传少阳，病在半表半里，有柴胡证，但见一证，便以小柴胡随证加
减治之，不必待其悉具也。
【集注】方有执曰∶此承上条辨认少阳一经为病之大旨。
郑重光曰∶有柴胡证，但见一证便是，不必悉具者，言往来寒热是柴胡证，此外兼见胸胁满硬，心烦喜呕，
及诸证中凡有一证者，
即是半表半里，故曰呕而发热者，小柴胡汤主之。因柴胡为枢机之剂，风寒不全在表未全入里者，皆可用，故
证不必悉具，而方有加减法也。至若柴胡有疑似证，不可不审者，如胁下满痛，本渴而饮水呕者，柴胡不中与
也；及但欲呕，胸中痛微溏者，亦非柴胡证，此等又当细为详辨者也。
伤寒三日，少阳脉小者，欲已也。
【注】伤寒该中风而言也。其邪三日，少阳受之，脉若大者，为邪盛欲传，今脉小，为邪衰欲自已也。
【集注】程应旄曰∶脉小则阳得阴以和，是邪尽退而正来复矣。
张锡驹曰∶三日乃少阳主气之期，脉小则病退也。
伤寒四五日，身热恶风，颈项强，胁下满，手足温而渴者，小柴胡汤主之。
【注】伤寒四五日，邪在三阳之时。身热恶风，太阳证也；颈项强，太阳阳明证也；胁下满，手足温而渴，
阳明少阳证也。此为三阳合病之始，固当权其孰缓孰急，以施其治。然其人胁下满，手足温而渴，是已露去表
入里，归并少阳之机，故独从少阳以为治也。主以小柴胡汤者，和解其表里也。此三阳合病不必悉俱柴胡证，
而当用柴胡之一法也。
【集注】方有执曰∶三阳俱见病，而独从少阳小柴胡以为治者，太阳、阳明之邪微，少阳近里而里证见，
故从少阳一于和而三善备也。
喻昌曰∶本当从三阳合并病之例而用表法，但手足温而加渴，是外邪逼凑于少阳，向里之机已着，更用辛
甘发散，则重增其热而大耗其津矣。故从小柴胡之和法，便阳邪罢而阴津不伤，一举而两得也。小柴胡汤当从
加减法，不呕而渴者，去半夏加栝蒌根为是。
张志聪曰∶手足温者，手足不冷也。非病患自觉其温，乃诊者按之而得也。不然何以既曰身热，而复云手
足温耶？
汪琥曰∶此条系三阳经齐病，而少阳之邪居多也。太阳伤寒已至四五日之时，不曰发热恶风，只曰身热者，
此太阳之邪渐衰也。其兼阳明证不曰鼻干不得卧，而只曰颈项强者，此阳明之邪，亦将衰也。惟胁下满为少阳
经之专证，况兼手足温而又渴，此为邪将传里之机已着也。
阳明病，发潮热，大便溏，小便自可，胸胁满不去者，与小柴胡汤。
【注】阳明病发潮热，当大便硬、小便数也，今大便溏、小便如常，非阳明入腑之潮热可知矣。况有胸胁
满不去之少阳证乎？故不从阳明治，而从少阳与小柴胡汤主之也。
【集注】王肯堂曰∶阳明为病，胃家实也。今便溏而言阳明病者，谓有阳明外证，身热汗出，不恶寒反恶热也。
少阳主司春季，其气机一半出于地表之外，一半潜藏于地中；人体之气也是如此，因此少阳主司半表半里的病位。所谓“半表”，指的是在外的太阳经；所谓“半里”，指的是在内的太阴经。邪气侵入其间，阴阳之气相互推移，寒热交替发作，邪气与正气相互对峙，进退互拒。在这个阶段，汗、吐、下三种治法都在禁忌之列，因此确立小柴胡汤（Minor Bupleurum Decoction）作为和解之法，根据病情加减施治。然而在小柴胡汤的加减法中，又有口不渴且身体有微热的情况，加桂枝（Cinnamon Twig）以取汗；以及经过攻下后出现胸胁部胀满且轻微结滞，小便不利，口渴但不呕吐，头部出汗，往来寒热的情况，使用柴胡桂枝干姜汤（Bupleurum, Cinnamon Twig and Dried Ginger Decoction）发汗。又有具备柴胡证（Bupleurum Syndrome），反而被误用攻下法，导致心下部胀满且硬痛的情况，这是结胸（Jie Xiong / Chest Binding），以大陷胸汤（Major Cathartic Pill for the Chest）主治；以及柴胡证仍在的情况，先给予小柴胡汤。如果呕吐不止，心下部拘急不适，心中郁郁微烦，说明病未解除，给予大柴胡汤（Major Minor Bupleurum Decoction）攻下。更有原本就是柴胡证，医生却用丸药攻下导致轻微腹泻，出现胸胁胀满而呕吐，下午定时发热（日晡潮热）的情况，用小柴胡加芒硝汤（Minor Bupleurum Decoction with Natrii Sulfas）攻下等治法。这说明张仲景也有汗法和下法，关键在于临证时详细诊察，因病施治，不可固执一端。
【注】少阳，即胆经（Gallbladder Meridian）。其经脉起于眼外角，从耳后进入耳中，挟行咽喉，出于下颌中。邪气损伤其经脉，所以出现口苦、咽干、目眩。口苦，是因为热蒸腾胆气上溢；咽干，是因为热耗伤津液；目眩，是因为热熏蒸眼部导致视物昏黑。这是揭示中风、伤寒邪气传入少阳的总纲，凡是篇中称为少阳中风、少阳伤寒的，就是指具备这些症状而言。
【集注】林澜说：《伤寒论》中提到少阳病，有胸胁痛、耳聋、往来寒热、心烦喜呕、胸胁痞硬等症状，半表半里的证候已经详尽了。这里为什么说是口苦、咽干、目眩呢？大概来说，病在经络方面，本篇的其他条文已经详尽说明了；如果是胆腑自病（Damp-Heat in Gallbladder），则又必然会有这些症状。
沈明宗说：这虽然是少阳的总证，但偏向于里了。少阳主胆，其经脉循行胁肋联络于耳，所以胸胁痛而耳聋。张仲景另出手眼，来补充口苦、咽干、目眩这些里证，这是概括了少阳风伤卫、寒伤营，以及风寒两伤的情况而言。
吴人驹说：少阳是一阳。少阳之上，由相火主导。如果从火化，火盛则干燥，所以口苦咽干。少阳属木，木主肝，肝主目，所以生病则目眩。
魏荔彤说：胆腑与少阳经互为表里，而不是指半表半里。半表，是相对于太阳的全表而言；半里，是相对于太阴的全里而言。所以少阳在半表半里之间，总是以经络的界限来说。又说：经文中所说的“不必悉具”，是指除了主要症状之外的其他兼证，而少阳经和胆腑的主病，没有不具备这些主要症状就匆忙诊断为少阳病的。
少阳中风，两耳听不见，眼睛发红，胸中胀满而烦躁，不可用吐法和下法，如果用吐下法，会导致心悸和惊恐。
【注】少阳，即第一条所说的口苦、咽干、目眩的症状。中风，是指这个少阳病是从中风的邪气传来。少阳的经脉，起于眼外角，从耳后进入耳中；其支脉，会合缺盆，下行胸中，循行胁肋。表邪传入其经脉，所以眼睛红、耳朵聋，胸中胀满而烦躁。然而这是少阳半表半里的胸满而烦，不同于太阳证具的邪气陷入胸中导致的胸满而烦，所以不可用吐、下法。如果用吐、下法，就会使中焦空虚，神志虚怯，就会导致心悸和惊恐。这是揭示中风邪气传入少阳的大纲。
【集注】程知说：少阳只宜和解，如果用吐法就会使其阳气虚弱而导致心悸，用下法就会使其阴血虚弱而导致惊恐。
汪琥说：少阳有禁用吐下的原因，只是因为烦满，所以误用了吐下法。成无己注解说：吐则伤气，气虚者悸；下则亡血，血虚者惊。不知道惊悸都主于心，误用吐下，则津液衰耗，神志虚怯，所以悸而惊。
沈明宗说：胸中烦满似乎可以用吐法，但在少阳，其邪气已经下行至胸并循行胁肋，用吐法徒然损伤胸中之气，使邪气内并逼迫神明，则悸而惊。
魏荔彤说：这一条论述张仲景没有出方剂。在小柴胡汤条中有心烦、心下悸的症状，想来不需要另外寻求方剂。汗、吐、下三法既然不可行，就应当和解。小柴胡汤是少阳对证的药物，此时使用它应该决断！
伤寒，脉象弦细，头痛发热的，属于少阳。少阳不可发汗，发汗则会出现谵语。这属于胃，胃气和顺则痊愈，胃气不和，则烦躁而心悸。
【注】不说“少阳伤寒”，而说“伤寒”，是简略的说法。意思是这个少阳病是从伤寒的邪气传来。脉象弦细，是少阳的脉象。上一条没有讲脉象，这里讲脉象，是补充说明。头痛发热无汗，是伤寒的证候，又兼见口苦、咽干、目眩等少阳的证候，所以说属于少阳。因为少阳的病已经属于半里，所以不可发汗。如果发汗，则会进一步损伤津液，助长热势，必定出现谵语。既然出现谵语，那就是转属胃了。如果其人津液素来充足，胃能自我调和，则或许可以痊愈；否则津液干枯，热结，胃不能调和，不但谵语，而且更加烦躁而心悸。这是揭示伤寒邪气传入少阳的大纲。
【集注】王肯堂说：凡是头痛、发热都属于在表，唯独这个头痛、发热属于少阳的原因是什么呢？因为其脉象弦细，所以知道邪气进入了少阳的界限。
喻昌说：少阳伤寒禁止发汗，少阳中风禁止吐、下，这两层意思互相列举，旨意更加严密。伤寒的头痛发热，适宜发汗的，尚且不可发汗，那么伤风的不可发汗，更不用说了。伤风的胸满而烦，似乎可用吐、下法，尚且不可吐、下，那么伤寒的不可吐、下，更不用说了。脉象弦细，是邪气欲入里，其在胃的津液已经被热消耗，再次发汗，将津液驱赶外出，怎么能不出现谵语呢？
汪琥说：误发其汗，出现谵语的，是夺去了津液导致胃干，所以言语错乱。这是少阳的邪气，已经转属胃。胃和则愈的意思，是说应当用药以下除胃中的热，使之和平。胃不和，不但谵语，更加烦躁惊悸，这是说胃热上犯于心，所以心神不宁。
伤寒五六天，或者中风，出现往来寒热，胸胁苦满，沉默不想饮食，心烦，喜欢呕吐，或者胸中烦闷而不呕吐，或者口渴，或者腹中痛，或者胁下痞硬，或者心下悸，小便不利，或者不渴，身体有微热，或者咳嗽的，以小柴胡汤主治。
【注】这是承接上面三条，详细阐述其证候，以明确其治法。伤寒或中风三四天，出现口苦、咽干、目眩的证候，以及弦细的脉象，知道邪气已经传入少阳。如果兼见耳聋、目赤、胸满而烦，就知道是从中风传来；如果兼见头痛、发热、无汗，就知道是从伤寒传来。现在到了五六天，又出现往来寒热、胸胁苦满、沉默不想饮食、心烦喜呕，就知道是中风、伤寒兼见俱有的证候。少阳的邪气，进可传入太阴之里，退可还归太阳之表，处于半表半里之间。其邪气外并于表，半表不解则产生恶寒；内并于里，半里不和则产生发热；或在表或在里无常，所以往来寒热不定。少阳的经脉，下行胸中循行胁肋，邪气凑聚其经脉，所以胸胁苦满；少阳邪气近于阴，所以沉默；少阳木邪生病则妨碍土（脾），所以不想饮食；邪气在胸胁，火无从宣泄，上逼于心，所以心烦；邪气欲入里，里气向外抗拒，所以呕吐；呕吐则木气舒展，所以喜欢呕吐。这些都是柴胡汤应有的证候。其余诸证，有时或有，总宜以小柴胡汤主治，各随见证进行加减治疗即可！既然区分了中风、伤寒的传变，为什么不区分其治法呢？因为太阳有营卫之分，所以风寒的辨别应当严格，等到传入阳明、少阳则没有营卫之分，且其邪气都化为热，所以同归一致。
【集注】成无己说：邪气在表里之间，叫做半表半里。伤寒中风，是指或者是伤寒或者是中风，不是伤寒之后再中风，也不是中风之后再伤寒。五六天，是邪气自表传里的时期，邪气在表则恶寒，在里则发热，现在在半表半里之间，没有定处，所以往来寒热。邪气在表，心腹不满；邪气在里，则心腹胀满，现在说胸胁苦满，也是在表里之间。邪气在表，呻吟不安；邪气在里，则内烦。经文说：阳入之阴，则静默默，因为邪气刚从表向里，处于表里之间。邪气在表则能食，邪气在里不能食，不欲食，还没有达到完全不能食的程度，所以也为在表里之间。邪气在表则不烦、不呕，邪气在里则烦满而呕，烦而喜呕，是邪气在表刚传里。邪气初入里，没有定处，所传不一，所以有或见的证候。
方有执说：五六天，大约是说的时间。往来寒热，是邪气进入躯壳之内，脏腑之外，两界之间的隙地，也就是所谓的半表半里，是少阳所主的部位。所以入而并于阴则寒，出而并于阳则热，出入无常，所以寒热间作。太阳一经，有营卫的不同，所以风寒异治；阳明切近太阳，营卫之道很近，风寒的辨别尚且严格；少阳一经，越过阳明离太阳远了，风寒无异治。经文以伤寒、中风五六日，往来寒热，交互为文，是为了发明风寒至此，同归于一致。
小柴胡汤方
柴胡（半斤） 黄芩（三两） 人参（三两） 半夏（洗，半升） 甘草（炙，三两） 生姜（切，三两） 大枣（擘，十二枚）
以上七味药，用水一斗二升，煮取六升，去滓再煎，取三升，温服一升，每日三次。
加减法：如果胸中烦闷而不呕吐，去掉半夏、人参，加栝蒌实一枚。如果口渴，去掉半夏，加人参合前成四两半，栝蒌根四两。如果腹中痛，去掉黄芩加芍药三两。如果胁下痞硬，去掉大枣加牡蛎四两。如果心下悸，小便不利，去掉黄芩加茯苓四两。如果不渴，外有微热，去掉人参加桂枝三两，温服微汗愈。如果咳嗽，去掉人参、大枣、生姜，加五味子半升，干姜二两。
【方解】邪气传入太阳、阳明，用汗、吐、下法；邪气传入少阳，只宜和解，汗、吐、下三法都在禁忌之列，因为其邪气在半表半里，而在躯壳之内界。在半表者，是客邪致病；在半里者，是主气受病。邪正双方在两界之间，各自无法进退而相互对峙，所以确立和解一法，既用柴胡解少阳在经之表寒，黄芩解少阳在腑之里热，还担心在里的太阴正气一虚，在经的少阳邪气乘虚而入，所以用姜、枣、人参和中而预先壮实里气，使里不受邪而调和，还表以作解。世俗之人不审察邪气所在，果在半表半里之间，以及是否应当和解的适宜性，及阴阳疑似的辨别，总以小柴胡汤为套方。医家庆幸自己处身无过，病人喜欢其药味平和，却不知道因循守旧误人，实在是不浅。所以凡治病的人，应当识得其未然，图谋先机于早。
【集解】程应旄说：方剂以小柴胡命名，是取配合少阳的意义。至于制方的旨意及加减法，则所说的上焦得通，津液得下，胃气因和，已经完全包含了。方中以柴胡疏木，使半表的邪气得从外宣散；黄芩清火，使半里的邪气得从内透达；半夏豁痰饮，降里气之逆，人参补内虚，助生发之气；甘草佐柴胡、黄芩，调和内外；姜、枣佐人参、半夏，通达营卫。相须相济，使邪气不至内向而外解。至于烦而不呕，是火气燥实逼迫胸膈，所以去人参、半夏，加栝蒌实。渴，是燥已耗液逼迫肺脏，所以去半夏加栝蒌根。腹中痛，是木气散入土中，胃阳受困，所以去黄芩以安土，加芍药以敛木。胁下痞硬，是邪气停留则木气实，所以去大枣之甘缓，加牡蛎之咸软。心下悸，小便不利，是水邪侵乎心，所以去黄芩之苦寒，加茯苓之淡渗。不渴身有微热，是半表之寒，尚滞留于肌表，所以去人参加桂枝以解之。咳，是半表之寒，凑入于肺，所以去参、枣，加五味子，易生姜为干姜以温之，虽然肺寒不减黄芩，恐怕干姜助热。总之邪在少阳，是半表半里之热，郁而不升，所以用小柴胡治之，所谓升、降、浮、沉则顺之也。
伤寒中风，有柴胡证，只要见到一个证候就可以，不必全部具备。
【注】这是承接上文而言，无论伤寒中风，邪气传入少阳，病在半表半里，有柴胡证，只要见到一个证候，便以小柴胡汤随证加减治疗，不必等待其全部具备。
【集注】方有执说：这是承接上一条辨认少阳一经为病的大旨。
郑重光说：有柴胡证，只要见到一个证候就可以，不必全部具备，是说往来寒热是柴胡证，此外兼见胸胁满硬、心烦喜呕，以及诸证中凡有一个证候的，就是半表半里，所以说呕而发热者，小柴胡汤主治。因为柴胡是枢机之剂，风寒不全在表未全入里的，都可以用，所以证候不必全部具备，而方剂有加减法。至于柴胡有疑似证候，不可不审察，如胁下满痛，本来口渴而饮水呕吐的，柴胡汤不适宜；以及只想呕吐，胸中痛大便微溏的，也不是柴胡证，这些又当仔细辨别。
伤寒三天，少阳脉小的，是病将要痊愈。
【注】伤寒包括中风而言。邪气三天，少阳受之，脉若大的，是邪盛欲传，现在脉小，是邪衰欲自止。
【集注】程应旄说：脉小则阳得阴以和，是邪气尽退而正气来复。
张锡驹说：三天是少阳主气的时期，脉小则病退。
伤寒四五天，身热恶风，颈项强，胁下满，手足温而渴的，小柴胡汤主治。
【注】伤寒四五天，邪气在三阳之时。身热恶风，是太阳证；颈项强，是太阳阳明证；胁下满，手足温而渴，是阳明少阳证。这是三阳合病的开始，固然应当权衡孰缓孰急，以施行治疗。然而其人胁下满，手足温而渴，是已经显露出去表入里，归并少阳的机转，所以独从少阳进行治疗。主治以小柴胡汤，是和解其表里。这是三阳合病不必全部具备柴胡证，而应当用柴胡之一法。
【集注】方有执说：三阳俱见病，而独从少阳小柴胡进行治疗，是因为太阳、阳明的邪气微，少阳近里而里证见，所以从少阳一于和而三善备。
喻昌说：本当从三阳合并病的例子而用表法，但手足温而加渴，是外邪逼凑于少阳，向里的机转已明显，再用辛甘发散，则会重增其热而大耗其津液。所以从小柴胡之和法，便阳邪罢而阴津不伤，一举而两得。小柴胡汤应当从加减法，不呕而渴，去掉半夏加栝蒌根是对的。
张志聪说：手足温，是指手足不冷。不是病人自觉其温，而是诊者按之而得。不然为什么既说身热，又说手足温呢？
汪琥说：这一条是三阳经齐病，而少阳的邪气居多。太阳伤寒已到四五天的时候，不说发热恶风，只说身热，这是太阳的邪气渐衰。其兼阳明证不说鼻干不得卧，只说颈项强，这是阳明的邪气，也将衰。惟独胁下满是少阳经的专证，何况兼手足温而又渴，这是邪气将传里的机转已明显。
阳明病，发潮热，大便溏，小便正常，胸胁满不去的，与小柴胡汤。
【注】阳明病发潮热，应当是大便硬、小便数，现在大便溏、小便如常，不是阳明入腑的潮热可知。况且有胸胁满不去的少阳证吗？所以不从阳明治，而从少阳与小柴胡汤主治。
Shaoyang governs spring; its qi emerges half outside the ground and remains half within it. Human qi is similar, thus Shaoyang governs the semi-exterior and semi-interior (Ban Biao Ban Li). "Semi-exterior" refers to Taiyang (Greater Yang) which is external; "semi-interior" refers to Taiyin (Greater Yin) which is internal. When pathogenic factors enter this space, yin and yang shift, alternating chills and fever occur, and pathogenic factors contend with healthy qi, mutually resisting advance and retreat. At this stage, the methods of sweating (Han), vomiting (Tu), and purging (Xia) are all contraindicated. Therefore, Xiaochaihu Tang (Minor Bupleurum Decoction) is established as a harmonizing method, applied with modifications based on the condition. However, within the modification rules of Xiaochaihu Tang, there are cases where the mouth is not dry and there is slight heat on the body; in such cases, Guizhi (Cinnamon Twig) is added to induce sweating. There are also cases after purging where there is fullness and slight binding in the chest and hypochondrium, difficulty in urination, thirst without vomiting, sweating only on the head, and alternating chills and fever; in these cases, Chaihu Guizhi Ganjiang Tang (Bupleurum, Cinnamon Twig and Dried Ginger Decoction) is used to induce sweating. Furthermore, if Chaihu syndrome (Bupleurum Syndrome) is present but purging is mistakenly applied, resulting in fullness and hard pain below the heart, this is Jie Xiong (Chest Binding), treated with Da Xiexiong Tang (Major Cathartic Pill for the Chest). If Chaihu syndrome persists, Xiaochaihu Tang is given first. If vomiting is incessant, there is urgency below the heart, and mild depression/irritability, the disease has not resolved; Da Chaihu Tang (Major Minor Bupleurum Decoction) is used for purging. Additionally, if the original condition was Chaihu syndrome, but the physician mistakenly used pill-based purgatives causing mild diarrhea, leading to fullness in the chest and hypochondrium, vomiting, and tidal fever in the late afternoon, Xiaochaihu Tang plus Mangxiao (Natrii Sulfas) is used for purging. This shows that Zhang Zhongjing also employed sweating and purging methods, but they depend on detailed clinical observation and treatment tailored to the disease; one must not adhere rigidly to a single approach.
The hallmark symptoms of Shaoyang disease are: bitter taste in the mouth, dry throat, and vertigo/dizziness.
[Annotation] Shaoyang corresponds to the Gallbladder Meridian (Dan Jing). Its vessel originates at the outer canthus, enters the ear from behind the ear, passes through the pharynx, and emerges at the jaw. Pathogenic damage to this meridian causes bitter taste, dry throat, and vertigo. Bitter taste results from heat steaming gallbladder qi upward; dry throat results from heat consuming body fluids; vertigo results from heat steaming the eyes causing visual disturbance. This outlines the general guideline for Wind-Stroke (Zhong Feng) and Cold Damage (Shang Han) pathogens transmitting to Shaoyang. Any mention of Shaoyang Wind-Stroke or Shaoyang Cold Damage in this chapter implies the presence of these symptoms.
[Collected Annotations] Lin Lan stated: The Treatise mentions Shaoyang disease with symptoms like hypochondriac pain, deafness, alternating chills and fever, irritability, frequent vomiting, and hypochondriac stiffness, detailing the semi-exterior semi-interior syndromes thoroughly. Why then does it say bitter taste, dry throat, and vertigo? Generally, for diseases in the meridians, other clauses in this chapter have already covered them; however, if the Gallbladder Fu organ itself is diseased, these symptoms must necessarily appear.
Shen Mingzong stated: Although this is the general syndrome of Shaoyang, it leans towards the interior. Shaoyang governs the Gallbladder, whose vessels circulate along the hypochondrium and connect to the ears, hence hypochondriac pain and deafness. Zhang Zhongjing employs a different perspective to supplement the interior symptoms of bitter taste, dry throat, and vertigo, encompassing Wind damaging Wei (Defensive Qi), Cold damaging Ying (Nutritive Qi), and both Wind and Cold affecting both.
Wu Renju stated: Shaoyang is the Single Yang. Above Shaoyang, Ministerial Fire (Xiang Huo) dominates. If transforming into fire, excessive fire causes dryness, hence bitter taste and dry throat. Shaoyang belongs to Wood, Wood governs the Liver, and the Liver governs the eyes; thus, when diseased, vertigo occurs.
Wei Litong stated: The Gallbladder Fu and Shaoyang Meridian are exterior-interior counterparts, not referring to semi-exterior semi-interior. Semi-exterior is relative to Taiyang's complete exterior; semi-interior is relative to Taiyin's complete interior. Thus, Shaoyang is between semi-exterior and semi-interior, always discussed in terms of meridian boundaries. He further said: What the text means by "not necessarily all present" refers to accompanying symptoms; the main diseases of the Shaoyang meridian and Gallbladder Fu cannot be diagnosed as Shaoyang disease without these primary manifestations being fully present.
Shaoyang Wind-Stroke presents with bilateral hearing loss, red eyes, chest fullness with irritability. Vomiting and purging are contraindicated; doing so leads to palpitations and fright.
[Annotation] "Shaoyang" refers to the symptoms mentioned in the first clause: bitter taste, dry throat, and vertigo. "Wind-Stroke" indicates this Shaoyang disease originated from Wind-Stroke pathogens. The Shaoyang meridian originates at the outer canthus, enters the ear from behind; its branch meets at the clavicular fossa, descends into the chest, and follows the hypochondrium. Exterior pathogens transmitting to this meridian cause red eyes, deafness, chest fullness, and irritability. However, this is chest fullness and irritability due to semi-exterior semi-interior Shaoyang pathology, distinct from the chest fullness and irritability caused by pathogens sinking into the chest in complete Taiyang syndromes. Therefore, vomiting and purging are contraindicated. If performed, they hollow out the middle jiao, leading to deficient spirit and timidity, resulting in palpitations and fright. This outlines the general principle of Wind-Stroke pathogens transmitting to Shaoyang.
[Collected Annotations] Cheng Zhi stated: Shaoyang should only be harmonized. Vomiting depletes Yang, causing palpitations; purging depletes Yin, causing fright.
Wang Hu stated: Shaoyang has contraindications for vomiting and purging precisely because of irritability and fullness, leading to their misuse. Cheng Wuji annotated: Vomiting injures Qi; Qi deficiency causes palpitations. Purging destroys Blood; Blood deficiency causes fright. They did not realize that both fright and palpitations are governed by the Heart. Mistaken vomiting and purging deplete body fluids and weaken the spirit, causing palpitations and fright.
Shen Mingzong stated: Chest irritability and fullness might seem suitable for vomiting, but in Shaoyang, the pathogen has descended to the chest and followed the hypochondrium. Vomiting merely injures Qi in the chest, forcing pathogens inward to oppress the Spirit, leading to palpitations and fright.
Wei Litong stated: This clause discusses Zhang Zhongjing not prescribing a formula. In the Xiaochaihu Tang clause, there are symptoms of heart irritability and epigastric palpitations; one need not seek another formula. Since sweating, vomiting, and purging are contraindicated, harmonization is required. Xiaochaihu Tang is the specific medicine for Shaoyang; its use should be decisive!
Cold Damage presenting with wiry-thin pulse, headache, and fever belongs to Shaoyang. Shaoyang is contraindicated for sweating; sweating leads to delirious speech. This involves the Stomach; if the Stomach harmonizes, recovery occurs; if not, irritability and palpitations ensue.
[Annotation] It says "Cold Damage" rather than "Shaoyang Cold Damage" for brevity, meaning this Shaoyang disease originated from Cold Damage pathogens. A wiry-thin pulse is characteristic of Shaoyang. The previous clause omitted the pulse; this one supplements it. Headache, fever, and anhidrosis are signs of Cold Damage. Combined with Shaoyang signs like bitter taste, dry throat, and vertigo, it is said to belong to Shaoyang. Since Shaoyang disease is already semi-interior, sweating is contraindicated. Sweating further damages fluids and aids heat, inevitably causing delirious speech. Once delirium occurs, the condition transfers to the Stomach. If the person's fluids are naturally sufficient and the Stomach self-regulates, recovery may occur; otherwise, fluid depletion and heat binding prevent Stomach harmony, leading not only to delirium but also to irritability and palpitations. This outlines the general principle of Cold Damage pathogens transmitting to Shaoyang.
[Collected Annotations] Wang Kentang stated: Headache and fever generally indicate exterior conditions. Why are these specific ones attributed to Shaoyang? Because the wiry-thin pulse indicates the pathogen has entered the Shaoyang boundary.
Yu Chang stated: Shaoyang Cold Damage prohibits sweating; Shaoyang Wind-Stroke prohibits vomiting and purging. Listing these two meanings makes the principles stricter. For Cold Damage headache and fever, even if sweating were appropriate, it is prohibited here; thus, for Wind-Stroke, it is certainly prohibited. For Wind-Stroke chest fullness and irritability, although vomiting/purging might seem appropriate, they are prohibited; thus, for Cold Damage, they are certainly prohibited. A wiry-thin pulse indicates the pathogen desires to enter the interior, and stomach fluids are already consumed by heat. Repeated sweating drives fluids outward, inevitably causing delirium.
Wang Hu stated: Mistaken sweating causes delirium by depriving fluids and drying the Stomach, leading to disordered speech. The Shaoyang pathogen has transferred to the Stomach. "Stomach harmonizes then recovers" means medication should be used to purge Stomach heat and restore harmony. If the Stomach does not harmonize, besides delirium, irritability and palpitations worsen, indicating Stomach heat offending the Heart, causing spiritual unrest.
After five or six days of Cold Damage or Wind-Stroke, presenting with alternating chills and fever, painful fullness in the chest and hypochondrium, silence with poor appetite, irritability, and frequent vomiting; or chest irritability without vomiting; or thirst; or abdominal pain; or hypochondriac stiffness; or epigastric palpitations with difficulty urinating; or no thirst with slight body heat; or coughing: Xiaochaihu Tang is the primary treatment.
[Annotation] This continues the previous three clauses, detailing symptoms to clarify treatment. After three or four days of Cold Damage or Wind-Stroke, observing bitter taste, dry throat, vertigo, and a wiry-thin pulse indicates transmission to Shaoyang. If accompanied by deafness, red eyes, chest fullness, and irritability, it indicates transmission from Wind-Stroke; if accompanied by headache, fever, and anhidrosis, it indicates transmission from Cold Damage. Now, at five or six days, the appearance of alternating chills and fever, painful chest/hypochondriac fullness, silence with poor appetite, irritability, and frequent vomiting indicates combined Wind-Stroke and Cold Damage signs. Shaoyang pathogens can advance to Taiyin interior or retreat to Taiyang exterior, residing in the semi-exterior semi-interior. If pathogens merge externally, unresolved semi-exterior causes chills; if merging internally, disharmonious semi-interior causes fever. Unpredictable location leads to alternating chills and fever. Shaoyang vessels descend through the chest and follow the hypochondrium; pathogens gathering here cause painful fullness. Shaoyang pathogens are close to Yin, causing silence. Shaoyang Wood pathology obstructs Earth (Spleen/Stomach), causing poor appetite. Pathogens in the chest/hypochondrium cannot vent fire, pressing upward on the Heart, causing irritability. Pathogens desiring to enter the interior meet resistance from interior Qi, causing vomiting; vomiting relaxes Wood Qi, hence the preference for vomiting. These are expected symptoms for Chaihu. Other symptoms may occasionally appear; Xiaochaihu Tang is the primary treatment, modified according to specific signs. Why distinguish Wind-Stroke/Cold Damage transmission but not treatment? Taiyang has Ying/Wei distinctions requiring strict differentiation, but upon transmission to Yangming and Shaoyang, Ying/Wei distinctions vanish, and pathogens transform into heat, unifying the treatment.
[Collected Annotations] Cheng Wuji stated: Pathogens between exterior and interior are called semi-exterior semi-interior. Cold Damage or Wind-Stroke means either one, not sequential attacks. Five or six days is when pathogens transmit from exterior to interior. Pathogens in exterior cause chills; in interior, heat. Here, between semi-exterior and semi-interior with no fixed location, alternating chills and fever occur. Pathogens in exterior do not cause abdominal fullness; in interior, they do. Chest/hypochondriac fullness indicates semi-exterior semi-interior status. Pathogens in exterior cause groaning; in interior, internal irritability. The Classic states: "Yang entering Yin becomes quiet." Silence occurs because pathogens move from exterior to interior, residing between them. Pathogens in exterior allow eating; in interior, they prevent it. Poor appetite, without total inability to eat, indicates semi-exterior semi-interior status. Pathogens in exterior cause no irritability/vomiting; in interior, they cause irritability/fullness/vomiting. Irritability with preference for vomiting indicates pathogens moving from exterior to interior. Initial entry into interior with no fixed location and varied transmission paths explains occasional symptoms.
Fang Youzhi stated: Five or six days is approximate. Alternating chills and fever occur when pathogens enter the space inside the shell but outside the zang-fu, the semi-exterior semi-interior domain of Shaoyang. Entering and merging with Yin causes chills; exiting and merging with Yang causes heat. Unpredictable movement causes alternating chills and fever. Taiyang has Ying/Wei differences requiring different treatments for Wind/Cold. Yangming is close to Taiyang, keeping Wind/Cold distinctions strict. Shaoyang is far from Taiyang past Yangming, so Wind/Cold treatments converge. The text interweaves Cold Damage/Wind-Stroke with alternating chills/fever to demonstrate that Wind and Cold unify at this stage.
Xiaochaihu Tang Formula
Chaihu (Half Jin), Huangqin (3 Liang), Renshen (3 Liang), Banxia (Washed, Half Sheng), Gancao (Roasted, 3 Liang), Shengjiang (Sliced, 3 Liang), Dazao (Broken, 12 pieces).
These seven ingredients are boiled in 12 Sheng of water to yield 6 Sheng, strained, and decocted again to yield 3 Sheng. Take 1 Sheng warm, three times daily.
Modification Rules: If chest irritability without vomiting, remove Banxia and Renshen, add Gualou Fruit (Trichosanthes Fruit) one piece. If thirsty, remove Banxia, increase Renshen to total 4.5 Liang, add Gualou Root (Trichosanthes Root) 4 Liang. If abdominal pain, remove Huangqin, add Shaoyao (Peony Root) 3 Liang. If hypochondriac stiffness, remove Dazao, add Muli (Oyster Shell) 4 Liang. If epigastric palpitations with difficulty urinating, remove Huangqin, add Fuling (Poria) 4 Liang. If no thirst with slight exterior heat, remove Renshen, add Guizhi (Cinnamon Twig) 3 Liang; take warm to induce slight sweating. If coughing, remove Renshen, Dazao, Shengjiang, add Wubeizi (Schisandra Berry) Half Sheng, Ganjiang (Dried Ginger) 2 Liang.
[Formula Analysis] For pathogens transmitting to Taiyang and Yangming, sweating, vomiting, and purging are used. For Shaoyang, only harmonization is suitable; the other three methods are contraindicated because pathogens are in the semi-exterior semi-interior, fighting within the inner boundary of the body. Semi-exterior involves external pathogens; semi-interior involves internal host qi. With pathogens and healthy qi stuck between boundaries, neither advancing nor retreating, harmonization is established. Chaihu resolves exterior cold in the Shaoyang meridian; Huangqin resolves interior heat in the Shaoyang Fu. To prevent Taiyin interior deficiency allowing Shaoyang meridian pathogens to invade, Shengjiang, Dazao, and Renshen are used to harmonize the middle and strengthen interior Qi, ensuring the interior is protected and harmonious, allowing pathogens to return to the exterior for resolution. Laypeople often indiscriminately use Xiaochaihu Tang as a standard prescription without assessing if pathogens are truly in the semi-exterior semi-interior or if harmonization is appropriate. Physicians feel safe using it, and patients appreciate its mild nature, unaware that this complacency causes significant harm. Therefore, physicians must anticipate conditions early and act promptly.
[Collected Exegesis] Cheng Yingmao stated: Named Xiaochaihu Tang to correspond with Shaoyang. The formulation principles and modifications embody the concept: "Upper Jiao opens, fluids descend, Stomach Qi harmonizes." Chaihu soothes Wood, dispersing semi-exterior pathogens externally; Huangqin clears fire, penetrating semi-interior pathogens internally; Banxia resolves phlegm-fluids, descending rebellious interior Qi; Renshen tonifies interior deficiency, aiding generating Qi; Gancao assists Chaihu/Huangqin to harmonize interior/exterior; Shengjiang/Dazao assist Renshen/Banxia to circulate Ying/Wei. Mutual support ensures pathogens do not move inward but resolve outward. For irritability without vomiting, dry-fire oppression of the chest requires removing Renshen/Banxia and adding Gualou Fruit. For thirst, dryness consuming fluids oppressing the Lung requires removing Banxia and adding Gualou Root. For abdominal pain, Wood Qi scattering into Earth confining Stomach Yang requires removing Huangqin to calm Earth and adding Shaoyao to restrain Wood. For hypochondriac stiffness, lingering pathogens causing Wood excess requires removing sweet-slowing Dazao and adding salty-softening Muli. For epigastric palpitations and difficult urination, Water pathogens offending the Heart require removing bitter-cold Huangqin and adding bland-draining Fuling. For no thirst with slight heat, semi-exterior cold lingering in muscles requires removing Renshen and adding Guizhi to resolve. For coughing, semi-exterior cold invading the Lung requires removing Renshen/Dazao, adding Wubeizi, replacing Shengjiang with Ganjiang to warm; Huangqin is retained despite Lung cold to prevent Ganjiang from aiding heat. In summary, Shaoyang pathology is semi-exterior semi-interior heat stagnating without ascending; Xiaochaihu Tang treats this by following the principles of ascending, descending, floating, and sinking.
If Cold Damage or Wind-Stroke presents with Chaihu syndrome, observing just one symptom is sufficient; all symptoms need not be present.
[Annotation] Continuing from above, regardless of Cold Damage or Wind-Stroke, if pathogens transmit to Shaoyang (semi-exterior semi-interior), and Chaihu syndrome is present, observing any single symptom allows for Xiaochaihu Tang modification; waiting for all symptoms is unnecessary.
[Collected Annotations] Fang Youzhi stated: This continues the previous clause to identify the main essence of Shaoyang disease.
Zheng Zhongguang stated: "Observing one Chaihu symptom is sufficient" means alternating chills and fever is a Chaihu symptom. If accompanied by hypochondriac fullness/stiffness, irritability/frequent vomiting, or any other symptom from the list, it indicates semi-exterior semi-interior status. Thus, "vomiting with fever" is treated with Xiaochaihu Tang. Chaihu is a pivot agent suitable for pathogens not fully in the exterior or interior. Hence, symptoms need not be complete, and formulas have modifications. However, differential diagnosis is crucial for similar Chaihu symptoms. For example, hypochondriac fullness/pain with thirst and drinking-induced vomiting contraindicates Chaihu Tang. Similarly, desire to vomit with chest pain and loose stools is not a Chaihu syndrome. These require careful discrimination.
On the third day of Cold Damage, if the Shaoyang pulse is small, the disease is about to resolve.
[Annotation] "Cold Damage" includes Wind-Stroke. On the third day, Shaoyang is affected. If the pulse is large, pathogens are strong and likely to transmit; if small, pathogens are weak and resolving spontaneously.
[Collected Annotations] Cheng Yingmao stated: A small pulse indicates Yang harmonizing with Yin, meaning pathogens have retreated and healthy Qi is recovering.
Zhang Xiqiu stated: Three days is the period governed by Shaoyang; a small pulse indicates disease retreat.
After four or five days of Cold Damage, presenting with body heat, aversion to wind, stiff neck, hypochondriac fullness, warm hands/feet, and thirst: Xiaochaihu Tang is the primary treatment.
[Annotation] Four or five days of Cold Damage places pathogens in the Three Yang stages. Body heat/aversion to wind is Taiyang; stiff neck is Taiyang/Yangming; hypochondriac fullness, warm extremities, and thirst are Yangming/Shaoyang. This is the onset of Three Yang Combined Disease. One must weigh urgency to treat. However, hypochondriac fullness, warm extremities, and thirst indicate a trend moving from exterior to interior, consolidating in Shaoyang. Thus, treatment focuses solely on Shaoyang. Xiaochaihu Tang harmonizes exterior and interior. This demonstrates that Three Yang Combined Disease does not require all Chaihu symptoms to be present, but the Chaihu method of harmonization is applicable.
[Collected Annotations] Fang Youzhi stated: Treating Three Yang combined disease solely via Shaoyang/Xiaochaihu Tang works because Taiyang/Yangming pathogens are mild, while Shaoyang is closer to the interior showing interior signs. Harmonizing Shaoyang achieves multiple benefits.
Yu Chang stated: Although exterior methods might seem appropriate for combined disease, warm extremities and thirst indicate exterior pathogens pressing into Shaoyang with a clear interior trend. Using acrid-sweet dispersal would increase heat and consume fluids. Xiaochaihu harmonization resolves Yang pathogens without injuring Yin fluids, achieving two goals at once. Modification: for no vomiting but thirst, remove Banxia and add Gualou Root.
Zhang Zhicong stated: "Warm hands/feet" means they are not cold. It is not patient-reported warmth but physician-palpated warmth. Otherwise, why state "body heat" and then "warm extremities"?
Wang Hu stated: This clause describes simultaneous involvement of all Three Yang meridians, predominantly Shaoyang. By day four or five of Taiyang Cold Damage, stating only "body heat" instead of "fever/aversion to wind" indicates declining Taiyang pathogens. Stating only "stiff neck" instead of "dry nose/restlessness" indicates declining Yangming pathogens. Only hypochondriac fullness is specific to Shaoyang. Combined with warm extremities and thirst, it confirms the trend of pathogens transmitting to the interior.
In Yangming disease, presenting with tidal fever, loose stools, normal urination, and persistent hypochondriac fullness: Give Xiaochaihu Tang.
[Annotation] Yangming tidal fever typically accompanies hard stools and frequent urination. Loose stools and normal urination indicate this is not Yangming Fu-organ tidal fever. Moreover, persistent hypochondriac fullness indicates Shaoyang syndrome. Therefore, treatment does not target Yangming but addresses Shaoyang with Xiaochaihu Tang.
[Collected Annotations] Wang Kentang stated: Yangming disease is "Stomach Fullness/Excess" (Wei Jia Shi). Describing loose stools as Yangming disease refers to Yangming exterior signs: body heat, sweating, aversion to heat rather than cold.