凡发热必察其表里有无兼证。而后可穷其致热之因。其但发热而表里别无兼证者。此内
伤
发热。不在此例。所谓兼证者。以外兼头痛恶寒身疼腰痛等证。此邪在表者也。内兼烦渴胸
腹痛不大便或下利等证。此邪在里者也。发热特其见端耳。必互勘明确。辨证方的。
凡发热必责重太阳者。以太阳属表。统司营卫。而为诸阳之主气。经云。阳者卫外而为
固也
。外邪之伤人。多由于卫之不固。故论外感病。必自太阳起。然太阳虽主表。而其根起于
至阴。此实表里上下。互相呼应。故由太阳而阳明而少阳。以及三阴。皆互见发热证详列于
后。
太阳之为病。脉浮。头项强痛而恶寒。不即发热也。其恶寒正发热之机也。论中所称为
太阳病者。即指此脉此证而言。他经皆仿此。
太阳中风。发热有汗。其脉浮缓。风则伤卫。宜桂枝以解肌。太阳伤寒。发热无汗。其
脉浮
紧。寒则伤营。宜麻黄以发汗。然桂枝证全在 热稀粥以助药力。取其 微似有汗。不可
令如水流漓。至麻黄证始取大发其汗。此麻黄桂枝分治风寒。截然二法。不能混同施治。其
或风寒两伤。营卫同病。经云。太阳中风。脉浮紧。发热恶寒。身疼痛。不汗出而烦躁者。
大青龙汤主之。又云。伤寒脉浮缓。身不疼。但重。乍有轻时。无少阴证者。大青龙汤发之
。盖中风脉宜浮缓。而反见浮紧之脉。伤寒脉宜浮紧。而反见浮缓之脉。即易桂枝麻黄之成
法。而主用大青龙汤大发其汗。此仲景治风寒之法。成方具在。而或谓仲景之法。详于风寒
。略于温热。此大不然。仲景于风寒之外。特揭明太阳病发热而渴不恶寒者为温病。此其辨
证最要
之诀。所以与风寒异者。全在渴不恶寒四字。风寒发热。必兼恶寒。今不恶寒。此宜辨者也
。风寒发热。口全不渴。必待传变之后。口始作渴。今病初起即渴。此又宜辨者也。又有所
谓湿温者。经云湿家之为病。一身尽疼。发热。身色如似熏黄。又云。太阳病。关节疼痛而
烦。脉沉而细者。此名湿痹。此仲景但言湿不言温也。而以论中所列种种湿证。加以发热而
渴不恶寒。则湿温之情状。自可比类而得。至于热病。仲景明云太阳中热者 是也。其人汗
出恶寒身热而渴也。此与温病同一口渴。而 病恶寒。温病不恶寒。又自有别。仲景处以人
参白虎汤。则不惟有其法而并有其方矣。此太阳病初起发热辨证之大法。乃伤寒切实下手
工夫。
有谓翕翕发热者。但表不里也。有谓蒸蒸发热者。自里而表也。太阳主表。其发热必兼
头
项强痛身疼痛等证。此皆太阳之部署。纯乎表者也。至阳明发热。则兼有烦满口渴等证。少
阳发热。则兼有胸胁满痛口苦喜呕等证。而其脉皆主浮。太阳之脉。或浮缓。或浮紧。阳明
之脉浮大。少阳之脉浮弦。若脉沉而不浮。三阴证中。亦互见发热证。其发热同而所以致热
之因不同。不得以发热为邪在表。概从太阳发表例施治。
阳明发热。与太阳异者。经云。阳明病外证云何。答曰。身热。汗自出。不恶寒。反恶
热也
。盖始则恶寒发热。今恶寒自罢。虽汗出而热仍不解者。即转属阳明之候。当此时。无论风
寒暑湿。所感不同。而同归火化。阳明病。仲景有发汗之禁。而治法宜分经府。其热虽甚而
尚在于经者。宜以甘寒直撤其热。如经云。伤寒若吐若下后。七八日不解。热结在里。表里
俱热。时时恶风。大渴。舌干燥而烦。欲饮水数升者。白虎加人参汤主之是也。其邪已入腑
而犹汗出发热者。如经云。太阳病三日。发汗不解。蒸蒸发热者。属胃也。调胃承气汤主之
。又云。阳明病发热汗多者。急下之。宜大承气汤是也。
少阳发热。仲景亦申发汗之禁。少阳病本主往来寒热。而亦有发热属少阳者。必兼胁
下满心烦
喜呕诸证。且其脉必弦。故经云。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。又云。伤寒发热。汗出不解。心下痞硬。呕吐而下利者。大柴胡汤主之。
盖胁痛呕渴。已明见少阳之半里证。虽发热表证未除。不得从太阳发表之例。而当以大小柴
胡
汤。半表半里治之也。又曰。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。盖弦为少阳之定脉。细则邪不在表。仲景恐人以头
痛发热。误为太阳证。故明指之曰此属少阳。而又申言之曰。少阳不可发汗。其所以辨其发
热之属少阳者。前二条以证辨。此一条以脉辨也。
太阴发热者。其脉不浮而沉。而更兼吐利腹痛诸证。经云。病发热恶寒头痛身疼吐下者
。此
属何病。答曰。此名霍乱。霍乱自吐下。又利止复更发热也。吐利本太阴病。利止复热者。
阴病转阳也。既已转阳。其脉当浮。故又曰。太阴病脉浮者可发汗。宜桂枝汤。吐下之后。
津液已伤。复又往往口渴发热。故又曰。霍乱头痛发热。身疼痛。热多欲饮水者。五苓散主
之。寒多不用水者。理中汤主之。此与阳经之发热。治各不同也。
少阴病发热。最易与太阳牵混。故仲景于大青龙证。必辨其无少阴证者。方取大发其汗。
而又
申言之曰。少阴病。脉沉细数。病为在里。不可发汗。又曰。少阴病脉微不可发汗。亡阳故
也。则少阴之不可发汗明矣。阴病必当转阳。故曰少阴病。吐利。手足不逆冷。反发热者不
死。盖太阳寒水之气。与少阴君火。相济为用。此之吐利。少阴为寒所抑。兹得阳热之气。
而其气还返于太阳。故反发热不死也。然何以辨其为少阴之发热也。经云。少阴之为
病。脉沉细。但欲寐也。沉细为少阴之定脉。但欲寐为少阴之定证。且太阴病吐利。手
足自温。此则手足逆冷。更加之以恶寒身蜷。其甚者厥冷无脉。又或咽痛烦躁便脓血种种危
证。死生呼吸。盖因少阴肾藏。分发水火。为先天根本。故其病情寒热错杂。变幻不测有如
此。至发热则阴寒之中。犹寓阳热之气。而强责少阴汗者。将其人之根本先拔。至于下厥上
竭则难治矣。其有寒邪直犯少阴。而即发热者。如经云少阴病。始得之。反发热脉沉者。麻
黄附子细辛汤主之。又曰。少阴病。得之二三日。麻黄附子甘草汤微发汗。以二三日无里证
。故微发汗也。盖必以附子镇摄肾中真阳。俾根本先固。而后可以引邪外出。此于微发汗之
中。而仍寓不发汗之义也。厥阴发热者。以其人厥与热之多少。辨病之进退。厥阴者。两阴
交尽之名。然阴尽之中。实寓阳生之义。故其时阴阳不相顺接便为厥。厥热相等。其病可愈
。厥多热少。此为病进。热多厥少。此为病退。所谓厥者。手足逆冷是也。逆甚而至于冷过
肘膝。则不名曰逆冷而直名曰厥。此时正藉发热为一线生阳可续。故发热为病欲愈之机也。
故曰伤寒先厥。后发热而利者。必自止。又伤寒热少厥微。欲得食者。其病为愈。若发热下利
至
甚。厥不止者死。又伤寒六七日不利。便发热而利。其人汗出不止者亦死。要知发热之后。
其脉必不沉而浮。乃为阴病转阳之真候。故曰脉微浮为欲愈。不浮为未愈。此又与少阴发热
同一义也。
伤寒之脉。始终一以静为主。故经云。伤寒二三日。脉若静者为不传。若脉数急者为欲传
也。
内经云。汗出而脉尚躁盛者死。是始热以脉静为易愈。而传变之后。又必以脉静为真愈之候
。凡病之自表而里者。以太阳为始。病之由里而表者。以厥阴为始。太阳虽主表。而其脉连
于风府。其根起于至阴。又与少阴为表里。仲景慎重不敢妄发其汗者以此。三阴病固不宜发
汗。即三阳经发热。其致热之因。又不全属太阳。如病起发热。即兼口渴汗出大便闭等证。
此由阳明而太阳者也。又如病起发热。即兼喜呕胸胁满痛等证。此由少阳而太阳者也。皆不
得借口于伤寒一日。太阳受之。概与发表也。
大约温热病起于阳明者居多。至湿温病。其邪伏于募原。募原属半表半里。故其
发热每兼胸痞腹满烦渴不大便等证。加以骨节烦疼。舌胎如积粉。其病先犯少阳与太阴。
而内连于胃府。外溢于太阳。湿家本自易汗出。尤不可重发其汗也。至所谓异气者。非于六气
之外。别具一气。盖六气本天地自然之令气。因其气之偏胜。而酿为厉气。故其病沿门传染
。长幼相似。乃称曰疫。而治法仍不离乎六气之中也。
有病已愈而复又发热者。此名遗热。由于起居饮食之不慎。凡病后饮食。最宜清淡。使
胃中
津液渐复。邪气全尽。自然健啖。而世俗每饫肥鲜。兼之喜投补益。皆所不宜。故内经曰。
病热少愈。食肉则复。多食则遗。此其禁也。然其热之复发。亦有虚有实。故内经云。视其
虚实。调其逆从。可使必已矣。至仲景食后劳复。以及大病瘥后。种种各法。载明论中。更
不待他求矣。
凡出现发热症状，必须审查其表证和里证是否有兼夹证候。然后才能探究导致发热的根本原因。如果仅仅是发热，而表里都没有其他兼夹证候的，这属于内伤发热，不在此处讨论的范围。所谓兼夹证候，是指外部兼有头痛、恶寒、身体疼痛、腰痛等症状，这是邪气在体表的征象；内部兼有烦躁、口渴、胸腹疼痛、大便不通或腹泻等症状，这是邪气在体内的征象。发热只是疾病表现的一个开端，必须综合参互考证以明确诊断，辨证准确后确立治疗方案。
凡是论述发热，必定重视太阳经，因为太阳经主司体表，统管营气和卫气，是诸阳经的主气。《内经》说：“阳气具有护卫体表并使其固密的作用。”外邪伤人，多是因为卫气不固所致。因此，论述外感病，必定从太阳经开始。然而太阳经虽然主表，但其根源起于至阴（指足少阴肾经），这实际上是表里上下互相呼应的结果。所以由太阳经传变到阳明经、少阳经，以及三阴经，都会见到发热证候，详细列述如下。
太阳经受邪所致的病证，表现为脉象浮，头项强痛且恶寒，此时并不立即发热。其恶寒正是即将发热的征兆。论中所称的太阳病，就是指这种脉象和症状而言。其他经络的病证都仿照这个原则。
太阳中风证，表现为发热、有汗，脉象浮缓。风邪伤害卫气，适宜用桂枝汤来解肌发表。太阳伤寒证，表现为发热、无汗，脉象浮紧。寒邪伤害营血，适宜用麻黄汤来发汗。然而，服用桂枝汤证时，必须喝热稀粥以助药力，取其微微似有汗出的效果，不可让汗出如水流漓般过多。至于麻黄汤证，则是取大发其汗的效果。这是麻黄汤和桂枝汤分别治疗风寒两种不同情况的方法，截然分为两法，不能混淆施治。如果有风寒两伤，营卫同时发病的情况，《内经》说：“太阳中风，脉象浮紧，发热恶寒，身体疼痛，无汗且烦躁的，以大青龙汤主治。”又说：“伤寒，脉象浮缓，身体不疼，只是沉重，偶尔有减轻的时候，没有少阴证候的，用大青龙汤发散。”大概中风证的脉象宜见浮缓，却反而见到浮紧的脉象；伤寒证的脉象宜见浮紧，却反而见到浮缓的脉象，这就改变了桂枝汤和麻黄汤的常规用法，而主要使用大青龙汤大发其汗。这是张仲景治疗风寒的方法，成方具在。但有人却说张仲景的方法，对风寒论述详尽，对温热病论述简略，这完全不对。张仲景在风寒之外，特别阐明太阳病中发热而口渴、不恶寒的是温病，这是辨证最关键的要诀。之所以与风寒不同的地方，全在于“渴”和“不恶寒”这四个字。风寒发热，必定兼有恶寒，现在不恶寒，这是需要辨别的。风寒发热，口完全不渴，必须等到病邪传变之后，口中才开始作渴，现在病初起就口渴，这也是需要辨别的。又有称为湿温病的，《内经》说：“湿病患者，全身疼痛，发热，身体颜色像被烟熏过的黄色。”又说：“太阳病，关节疼痛且烦躁，脉象沉而细的，这名叫湿痹。”这里张仲景只说了湿而没有说温，但如果把论中所列的各种湿证，加上发热、口渴、不恶寒的症状，那么湿温病的情状，自然可以通过类比推导出来。至于热病，张仲景明确说：“太阳中热者，就是暑病。”其人汗出、恶寒、身热且口渴。这与温病同样有口渴，但暑病恶寒，温病不恶寒，又自有区别。张仲景用人参白虎汤治疗，那么不仅有治疗方法，还有具体方剂了。这是太阳病初起发热辨证的大法，也是治疗伤寒切实入手的基本功夫。
有人说“翕翕发热”（形容发热如羽毛覆盖般温和），这只是表证，不涉及里证。有人说“蒸蒸发热”（形容发热如蒸汽内蒸），这是由里达表的证候。太阳主表，其发热必定兼有头项强痛、身体疼痛等证候，这些都是太阳经的部署，纯粹属于表证。到了阳明经发热，则兼有烦闷、口渴等证候；少阳经发热，则兼有胸胁满痛、口苦、喜欢呕吐等证候，而且它们的脉象都以浮为主。太阳经的脉象，或浮缓，或浮紧；阳明经的脉象浮大；少阳经的脉象浮弦。如果脉象沉而不浮，在三阴证中，也间杂见到发热证候。虽然发热相同，但导致发热的原因不同，不能因为发热就认为邪气在表，一概按照太阳经发表的方法来治疗。
阳明经发热，与太阳经不同的地方，《内经》说：“阳明病的外证是什么？回答说：身体热，汗自出，不恶寒，反而恶热。”大概起初是恶寒发热，现在恶寒自行停止，虽然出汗但热仍不解的，这就是转属阳明经的征候。在这个时候，无论感受的是风寒暑湿哪种邪气，最终都归于火化。对于阳明病，张仲景有禁止发汗的规定，治疗方法应分经证和腑证。如果热势虽盛但还在经的，适宜用甘寒之品直接撤除热邪，如《内经》所说：“伤寒如果经过吐法或下法后，七八天病仍未解，热结在体内，表里俱热，时时恶风，极度口渴，舌干燥且烦躁，想要喝几升水的，用白虎加人参汤主治。”如果邪气已经入腑而仍然汗出发热的，如《内经》所说：“太阳病三天，发汗后病未解，蒸蒸发热的，属于胃腑实证，用调胃承气汤主治。”又说：“阳明病发热汗多的，应当急下，宜用大承气汤。”
少阳经发热，张仲景也重申禁止发汗。少阳病本以往来寒热为主，但也有发热属于少阳经的，必定兼有胁下满闷、心烦、喜欢呕吐等证候，而且脉象必定弦。所以《内经》说：“伤寒四五日，身热恶风，颈项强，胁下满，手足温且口渴的，用小柴胡汤主治。”又说：“伤寒发热，汗出后病不解，心下痞硬，呕吐且腹泻的，用大柴胡汤主治。”大概胁痛、呕吐、口渴，已经明显见到少阳经半表半里的证候，虽然发热表证未除，不得按照太阳经发表的例子治疗，而应当用大小柴胡汤，在半表半里之间进行治疗。又说：“伤寒脉象弦细，头痛发热的，属于少阳经。少阳经不可发汗，发汗就会谵语，这属于胃腑不和，胃气和顺则痊愈，胃气不和则烦躁且心悸。”大概弦脉是少阳经的定脉，细脉说明邪气不在表。张仲景恐怕人们因为头痛发热，误认为是太阳证，所以明确指出说“这属于少阳”，又进一步强调说“少阳经不可发汗”。他辨别发热属于少阳经的方法，前两条通过症状辨别，这一条通过脉象辨别。
太阴经发热，其脉象不浮而沉，并且兼有呕吐、腹泻、腹痛等证候。《内经》说：“患病发热恶寒、头痛、身体疼痛、呕吐或腹泻的，这属于什么病？回答说：这名叫霍乱。霍乱自身吐泻，又腹泻停止后又再次发热。”呕吐腹泻本属太阴病，腹泻停止后又发热，这是阴病转阳的表现。既然已经转阳，脉象应当浮，所以又说：“太阴病脉象浮的，可以发汗，宜用桂枝汤。”呕吐腹泻之后，津液已经受损，往往又会出现口渴发热，所以又说：“霍乱头痛发热，身体疼痛，热多想喝水的，用五苓散主治；寒多不想喝水的，用理中汤主治。”这与阳经的发热，治疗方法各不相同。
少阴病发热，最容易与太阳病混淆，所以张仲景在大青龙汤证中，必定辨别其没有少阴证候，才取大发其汗的方法。又进一步强调说：“少阴病，脉象沉细数，病在里，不可发汗。”又说：“少阴病脉微不可发汗，因为会亡阳。”这样少阴经不可发汗就很明确了。阴病必定当转阳，所以说：“少阴病，呕吐腹泻，手足不逆冷，反而发热的，不会死。”大概太阳寒水之气，与少阴君火，相互济助发挥作用。这里的呕吐腹泻，是因为少阴为寒邪所抑制，现在得到阳热之气，其气返还于太阳，所以反而发热而不至于死亡。然而如何辨别其为少阴经的发热呢？《内经》说：“少阴之为病，脉象沉细，只想睡觉。”沉细是少阴经的定脉，只想睡觉是少阴经的定证。而且太阴病呕吐腹泻，手足自然温暖，这里却是手足逆冷，再加上恶寒、身体蜷缩，严重的甚至四肢厥冷、无脉，或者咽喉痛、烦躁、便脓血等各种危重证候，生死只在呼吸之间。大概因为少阴肾藏，分发水火，是先天根本，所以其病情寒热错杂，变幻莫测达到如此程度。至于发热，则在阴寒之中，还寓含阳热之气，如果强行责求少阴经发汗，将会拔除病人的根本，以至于下焦厥冷、上焦血竭，就很难治疗了。如果有寒邪直接侵犯少阴，随即发热的，如《内经》说：“少阴病，刚得病时，反而发热，脉象沉的，用麻黄附子细辛汤主治。”又说：“少阴病，得病二三日，用麻黄附子甘草汤微发汗，因为二三日没有里证，所以微发汗。”大概必须用附子镇摄肾中的真阳，使根本先稳固，然后才可以引邪气外出。这是在微发汗之中，仍然蕴含不发汗的意义。
厥阴经发热，是根据病人厥冷与发热时间的多少，来辨别疾病的进退。厥阴，是两阴交尽的名称。然而在阴尽之中，实际上寓含阳生之义。所以当阴阳不相顺接时就发生厥冷。厥冷与发热时间相等，病可痊愈；厥冷多发热少，这是病进；发热多厥冷少，这是病退。所谓厥，就是手足逆冷。逆冷严重以至于冷过肘膝，就不叫逆冷而直接叫厥。此时正借助发热作为一线生机延续阳气，所以发热是疾病欲愈的征兆。所以说：“伤寒先厥冷，后来发热且腹泻的，腹泻必定自止。”又说：“伤寒热少厥微，想吃东西的，病将痊愈。”如果发热且腹泻非常严重，厥冷不止的，预后不良。又说：“伤寒六七日本来不腹泻，突然发热且腹泻，其人汗出不止的，也预后不良。”要知道发热之后，其脉象必定不沉而浮，这才是阴病转阳的真正征候。所以说：“脉象微浮为欲愈，不浮为未愈。”这又与少阴发热的道理相同。
伤寒的脉象，始终一以静缓为主，所以《内经》说：“伤寒二三日，脉象若静缓的，是不传变。如果脉象数急的，是欲传变。”《内经》说：“出汗后脉象仍然躁盛的，预后不良。”这是开始发热以脉静为容易痊愈，而传变之后，又必须以脉静为真正痊愈的征候。凡是病邪从表入里的，以太阳经为起始；病邪由里出表的，以厥阴经为起始。太阳经虽然主表，但其脉连于风府，其根起于至阴，又与少阴经互为表里。张仲景慎重不敢妄用发汗法，原因就在这里。三阴病固然不宜发汗，即使是三阳经发热，其导致发热的原因，又不全属于太阳经。如病起发热，就兼有口渴、汗出、大便闭结等证候，这是由阳明经传变到太阳经的。又如病起发热，就兼有喜欢呕吐、胸胁满痛等证候，这是由少阳经传变到太阳经的，都不得借口于“伤寒一日，太阳受之”，一概给予发表治疗。
大概温热病起于阳明经的居多。至于湿温病，其邪气伏匿于募原，募原属于半表半里，所以其发热常常兼有胸痞、腹满、烦渴、大便不通等证候，加上骨节烦疼，舌苔如积粉，其病先侵犯少阳经与太阴经，而内连于胃腑，外溢于太阳经。湿病患者本来就容易出汗，尤其不可再次强力发汗。至于所谓的异气（疫气），并非在六气之外别具一气，大概是六气本是天地自然的时令之气，因为气的偏胜，而酿成厉气，所以其病沿门传染，长幼症状相似，才称为疫，而治疗方法仍不离乎六气之中。
有病已痊愈而又再次发热的，这名叫遗热。由于起居饮食不慎所致。凡是病后饮食，最宜清淡，使胃中津液逐渐恢复，邪气完全清除，自然能正常进食，而世俗往往饱食肥甘鲜美之物，加之喜欢投用补益药物，都是不适宜的。所以《内经》说：“病热稍愈，吃肉则复发，多吃则遗留余热。”这是禁忌。然而其热的复发，也有虚证和实证之分，所以《内经》说：“观察其虚实，调理其逆从，可以使病必愈。”至于张仲景关于食后劳复，以及大病瘥后种种各法，都载明在《伤寒论》中，更不需要向其他地方寻求了。
Whenever fever occurs, one must examine whether there are accompanying syndromes in the exterior (Biao) or interior (Li). Only then can the root cause of the fever be thoroughly investigated. If there is merely fever without any other accompanying syndromes in the exterior or interior, this belongs to internal injury fever (Nei Shang Fa Re), which is not covered in this context. The so-called accompanying syndromes refer to external symptoms such as headache, aversion to cold (E Han), body pain, and lower back pain, indicating that the pathogen is in the exterior; or internal symptoms such as irritability, thirst, chest and abdominal pain, constipation, or diarrhea, indicating that the pathogen is in the interior. Fever is merely the initial manifestation; one must cross-reference and clarify the diagnosis to formulate an accurate treatment plan.
In discussing fever, emphasis is always placed on the Taiyang (Greater Yang) channel, because the Taiyang governs the exterior, controls Ying (Nutritive Qi) and Wei (Defensive Qi), and serves as the master qi of all Yang channels. The Classic states: "Yang protects the exterior and maintains solidity." External pathogens often attack due to the insecurity of Wei Qi. Therefore, when discussing exogenous diseases, one always begins with the Taiyang channel. However, although Taiyang governs the exterior, its root originates from Zhi Yin (referring to the Foot-Shaoyin Kidney channel). This reflects the mutual resonance between the interior and exterior, upper and lower. Thus, from Taiyang transmitting to Yangming (Stomach), Shaoyang (Gallbladder), and the Three Yin channels, fever syndromes are intermixed and detailed below.
The disease of the Taiyang channel presents with a floating pulse (Mai Fu), stiffness and pain in the head and nape, and aversion to cold. Fever does not occur immediately. The aversion to cold is the mechanism preceding fever. The "Taiyang Disease" mentioned in the Treatise refers specifically to this pulse and these symptoms. Diseases of other channels follow this principle.
Taiyang Wind Strike (Zhong Feng) presents with fever and sweating, with a floating and moderate pulse. Wind damages Wei Qi; Guizhi Tang (Cinnamon Twig Decoction) should be used to resolve the muscle layer. Taiyang Cold Damage (Shang Han) presents with fever and no sweating, with a floating and tight pulse. Cold damages Ying Blood; Mahuang Tang (Ephedra Decoction) should be used to induce sweating. However, for the Guizhi Tang syndrome, one must drink hot thin porridge to assist the medicinal power, aiming for a slight, uniform perspiration, not allowing sweat to flow profusely. In contrast, the Mahuang Tang syndrome aims to induce heavy sweating. These are two distinct methods for treating Wind and Cold respectively using Mahuang Tang and Guizhi Tang, which cannot be confused. If both Wind and Cold injure simultaneously, affecting both Ying and Wei, the Classic states: "In Taiyang Wind Strike, if the pulse is floating and tight, with fever, aversion to cold, body pain, no sweating, and irritability, Da Qing Long Tang (Major Blue Green Dragon Decoction) is the primary treatment." It also states: "In Cold Damage, if the pulse is floating and moderate, the body is not painful but heavy, occasionally feeling lighter, and there are no Shaoyin signs, Da Qing Long Tang is used to disperse." Generally, Wind Strike pulses should be floating and moderate, yet a floating and tight pulse appears; Cold Damage pulses should be floating and tight, yet a floating and moderate pulse appears. This alters the standard methods of Guizhi and Mahuang, leading to the primary use of Da Qing Long Tang to induce heavy sweating. This is Zhang Zhongjing's method for treating Wind and Cold, with established formulas available. Some claim that Zhang's methods are detailed for Wind and Cold but brief for Warmth (Wen Re); this is incorrect. Outside of Wind and Cold, Zhang explicitly identifies Taiyang disease with fever, thirst, and no aversion to cold as Warm Disease (Wen Bing). This is the most crucial key to differentiation. The difference from Wind and Cold lies entirely in "thirst" and "no aversion to cold." Wind and Cold fever must include aversion to cold; the absence of aversion to cold here requires differentiation. Wind and Cold fever involves no initial thirst; thirst only arises after transmission. Here, thirst appears at the onset, requiring further differentiation. There is also what is called Damp-Warmth (Shi Wen). The Classic says: "For patients with Dampness, the whole body aches, there is fever, and the body color resembles smoke-stained yellow." It also says: "In Taiyang disease, joint pain with irritability and a sinking, fine pulse is named Damp Bi (Dampness Obstruction)." Here, Zhang mentions Dampness but not Warmth. However, by adding the symptoms of fever, thirst, and no aversion to cold to the various Dampness syndromes listed in the Treatise, the characteristics of Damp-Warmth can be deduced by analogy. As for Heat Disease, Zhang clearly states: "Sun Heat in Taiyang is Shu (Summerheat). The person sweats, has aversion to cold, body heat, and thirst." This shares thirst with Warm Disease, but Shu includes aversion to cold while Warm Disease does not, marking a distinction. Zhang treats it with Renshen Baihu Tang (Ginseng White Tiger Decoction), providing both method and formula. This is the general method for differentiating fever at the onset of Taiyang disease, representing the practical foundation for treating Shanghan (Cold Damage).
Some describe "Xi Xi Fa Re" (fever like feathers covering, mild warmth) as purely exterior without interior involvement. Others describe "Zheng Zheng Fa Re" (fever steaming from within) as originating from the interior and reaching the exterior. Taiyang governs the exterior; its fever must accompany head/nape stiffness, body pain, etc., which are deployments of Taiyang, purely exterior. Yangming fever accompanies irritability, fullness, and thirst. Shaoyang fever accompanies chest/hypochondriac fullness/pain, bitter taste, and desire to vomit. Their pulses are all primarily floating. Taiyang pulse may be floating-moderate or floating-tight; Yangming pulse is floating-large; Shaoyang pulse is floating-wiry. If the pulse is sinking and not floating, fever syndromes also appear among the Three Yin diseases. Although the fever is the same, the causes differ; one cannot assume the pathogen is in the exterior simply because of fever and treat all according to Taiyang exterior-releasing methods.
Yangming fever differs from Taiyang. The Classic asks: "What are the external manifestations of Yangming disease?" Answer: "Body heat, spontaneous sweating, no aversion to cold, but aversion to heat." Initially, there is aversion to cold and fever; now aversion to cold ceases spontaneously. Even with sweating, if heat persists, it indicates transformation into Yangming. At this stage, regardless of whether the pathogen was Wind, Cold, Summerheat, or Dampness, it ultimately transforms into Fire. For Yangming disease, Zhang Zhongjing prohibits sweating. Treatment should distinguish between Channel (Jing) and Fu organ syndromes. If heat is severe but still in the Channel, sweet-cold herbs should directly clear the heat. As stated: "After vomiting or purging in Cold Damage, if unresolved after 7-8 days, heat binds internally, causing exterior and interior heat, occasional aversion to wind, extreme thirst, dry tongue, irritability, and desire to drink several liters of water, Baihu Jia Renshen Tang (White Tiger Plus Ginseng Decoction) is used." If the pathogen has entered the Fu organ but sweating and fever persist: "Three days after Taiyang disease, if sweating fails to resolve the condition and there is steaming fever, it belongs to the Stomach; Tiaowei Chengqi Tang (Regulate the Stomach and Order the Qi Decoction) is used." Also: "In Yangming disease, if there is fever and excessive sweating, urgent purging is required; Da Chengqi Tang (Major Order the Qi Decoction) is indicated."
Shaoyang fever also carries a prohibition against sweating. Shaoyang disease typically features alternating chills and fever, but fever can belong to Shaoyang, accompanied by hypochondriac fullness, irritability, and desire to vomit, with a wiry pulse. Thus: "Four or five days after Cold Damage, if there is body heat, aversion to wind, neck stiffness, hypochondriac fullness, warm hands/feet, and thirst, Xiao Chaihu Tang (Minor Bupleurum Decoction) is used." Also: "If Cold Damage fever persists despite sweating, with epigastric hardness, vomiting, and diarrhea, Da Chaihu Tang (Major Bupleurum Decoction) is used." Hypochondriac pain, vomiting, and thirst clearly indicate Shaoyang half-exterior/half-interior syndromes. Even if exterior fever remains, one must not use Taiyang exterior-releasing methods, but treat the half-exterior/half-interior with Xiao or Da Chaihu Tang. Furthermore: "If the pulse is wiry and fine with headache and fever, it belongs to Shaoyang. Shaoyang must not be induced to sweat; doing so leads to delirium, indicating stomach disharmony. If the stomach harmonizes, recovery occurs; if not, irritability and palpitations result." Wiry is the definitive pulse of Shaoyang; fine indicates the pathogen is not in the exterior. Zhang warns against mistaking headache and fever for Taiyang, clarifying it as Shaoyang and reiterating the prohibition against sweating. The first two points differentiate Shaoyang fever by symptoms; this point differentiates by pulse.
Taiyin fever presents with a sinking, non-floating pulse, accompanied by vomiting, diarrhea, and abdominal pain. The Classic asks: "Fever, aversion to cold, headache, body pain, vomiting, and diarrhea—what disease is this?" Answer: "This is Huoluan (Cholera-like disorder). Huoluan involves spontaneous vomiting and diarrhea; if diarrhea stops and fever returns..." Vomiting and diarrhea belong to Taiyin. Fever returning after diarrhea stops indicates Yin transforming into Yang. Having transformed to Yang, the pulse should become floating. Hence: "If Taiyin disease pulse is floating, sweating may be induced; Guizhi Tang is appropriate." After vomiting and diarrhea, fluids are damaged, often leading to thirst and fever. Hence: "For Huoluan with headache, fever, body pain, more heat than cold, and desire to drink, Wuling San (Five Ingredient Powder with Poria) is used. If more cold than heat and no desire to drink, Lizhong Tang (Regulate the Middle Decoction) is used." This differs from Yang channel fever treatments.
Shaoyin fever is easily confused with Taiyang. Thus, for Da Qing Long Tang, Zhang insists on excluding Shaoyin signs before inducing heavy sweating. He emphasizes: "Shaoyin disease with sinking, fine, rapid pulse is interior; do not sweat." Also: "Shaoyin disease with faint pulse must not be sweated, as it causes Yang collapse." Thus, Shaoyin forbids sweating. Yin diseases must transform to Yang. "Shaoyin disease with vomiting, diarrhea, non-cold limbs, and return of fever indicates survival." Taiyang Cold Water and Shaoyin Ministerial Fire complement each other. Here, Shaoyin is suppressed by Cold; receiving Yang heat allows Qi to return to Taiyang, hence fever without death. How to identify Shaoyin fever? The Classic states: "Shaoyin disease presents with sinking, fine pulse and desire to sleep." Sinking/fine is the definitive pulse; desire to sleep is the definitive symptom. Unlike Taiyin where limbs are warm, Shaoyin has cold limbs, plus aversion to cold and curling up. Severe cases have cold limbs beyond elbows/knees, no pulse, sore throat, irritability, or pus/blood in stool. Life hangs in the balance. Shaoyin Kidney stores Water and Fire, the root of congenital essence, leading to complex cold-heat patterns. Fever implies Yang heat within Yin cold. Forcing sweating in Shaoyin destroys the root, leading to lower Jue and upper exhaustion, which is difficult to treat. If Cold directly invades Shaoyin causing immediate fever: "Shaoyin disease, just acquired, with return of fever and sinking pulse, uses Mahuang Fuzi Xixin Tang (Ephedra, Aconite, and Asarum Decoction)." Also: "Shaoyin disease, 2-3 days later, uses Mahuang Fuzi Gancao Tang for mild sweating, as there are no interior signs." Fuzi stabilizes Kidney True Yang to secure the root before expelling pathogens. This mild sweating contains the meaning of not sweating.
Jueyin fever is judged by the ratio of Jue (cold extremities) to Re (fever) to determine disease progression. Jueyin means the end of two Yins. Within this end lies the generation of Yang. When Yin and Yang fail to connect smoothly, Jue occurs. Equal Jue and Re indicate recovery; more Jue than Re indicates progression; more Re than Jue indicates regression. Jue refers to cold extremities. Extreme cold beyond elbows/knees is called Jue. Here, fever serves as a thread of surviving Yang, indicating impending recovery. "Shanghan starting with Jue, followed by fever and diarrhea, will see diarrhea stop." "Shanghan with little heat and slight Jue, desiring food, indicates recovery." If fever and severe diarrhea persist with unending Jue, death ensues. "Six or seven days after Shanghan, if no diarrhea initially, but sudden fever and diarrhea with endless sweating, death ensues." After fever, the pulse must rise from sinking to floating, indicating Yin transforming to Yang. "Slightly floating pulse indicates recovery; non-floating indicates otherwise." This aligns with Shaoyin fever principles.
Shanghan pulses remain quiet/still throughout. "Two or three days after Shanghan, if the pulse is quiet, it does not transmit. If rapid and urgent, it transmits." The Classic states: "If sweating occurs but the pulse remains restless, death results." Initial fever heals if the pulse is quiet; post-transmission healing requires a quiet pulse. Diseases moving from exterior to interior start with Taiyang; those moving from interior to exterior start with Jueyin. Taiyang governs the exterior, connects to Fengfu, roots in Zhi Yin, and pairs with Shaoyin. Zhang refrains from reckless sweating due to this. Three Yin diseases forbid sweating. Even Yang channel fevers may not originate from Taiyang. Onset with thirst, sweating, and constipation suggests Yangming transmitting to Taiyang. Onset with vomiting and hypochondriac pain suggests Shaoyang transmitting to Taiyang. One cannot cite "Day one, Taiyang receives the pathogen" to justify universal exterior release.
Warm diseases mostly originate in Yangming. Damp-Warmth pathogens lodge in Mu Yuan (Omentum/Source), a half-exterior/half-interior location. Fever accompanies chest oppression, abdominal fullness, irritability, thirst, and constipation, plus bone/joint pain and a coating like accumulated powder. The disease attacks Shaoyang and Taiyin first, connecting internally to the Stomach Fu and externally overflowing to Taiyang. Damp patients sweat easily; heavy sweating must be avoided. "Yi Qi" (Pestilential Qi) is not a seventh Qi outside the Six Qi. The Six Qi are natural seasonal forces; excess leads to pestilence, causing contagious illness with similar symptoms across ages. Treatment still adheres to the Six Qi principles.
Fever recurring after recovery is called "Yi Re" (Lingering Heat), caused by improper diet or activity. Post-illness diet should be light to restore Stomach fluids and eliminate pathogens, allowing normal appetite. Eating rich/fatty foods or using tonics is inadvisable. The Classic warns: "When heat subsides slightly, eating meat causes relapse; overeating causes lingering heat." Recurrent fever can be Deficient or Excess. The Classic advises: "Assess deficiency/excess, regulate reversal/normalcy, ensuring cure." Zhang's methods for post-meal labor recurrence or post-major illness care are detailed in the Treatise, requiring no external sources.