太阳表证初起。舌多无苔而润。即有亦微白而薄。甚或苔色淡白。惟素多痰湿者。苔多白滑。舌色淡红。素禀血热
者。苔虽微白。舌色反红。若传入本腑。膀胱蓄溺。苔多纯白而浓。却不干糙。膀胱蓄热。苔多白兼微黄。薄而润滑。
【秀按】太阳气化主水。而性本寒。寒为阴邪。白为凉象。故苔色多白。白润白薄。是其本象。若白滑者。
风寒兼湿也。白滑而腻者。风寒兼湿夹痰也。或薄或浓者。视其痰湿之多少也。惟苔色淡白。白而嫩滑。素体
虚寒也。
【廉勘】苔色白而薄者。寒邪在表。固已。然必白浮滑薄。其苔刮去即还者。太阳经表受寒邪也。若全舌白
苔。浮涨浮腻。渐积而干。微浓而刮不脱者。寒邪欲化火也。如初起白薄而燥刺者。温病因感寒而发。肺津已
伤也。内薄而粘腻者。湿邪在于气分也。故同一苔色薄白。一主寒邪在表。一主气郁不舒。一主肺津受伤。
少阳主半表半里。偏于半表者。舌多苔色白滑。或舌尖苔白。或单边白。或两边白。偏于半里者。舌多红
而苔白。间现杂色。或尖白中红。或边白中红。或尖红中白。或尖白根黑。或尖白根灰。若白苔多而滑。黄灰苔
少者。半表证多。
红舌多而白苔少。或杂黄色灰色者。半里证多。如边白滑润。虽中心黄黑。仍属半表半里。惟白苔粗如积粉。两边
色红或紫者。温疫伏于膜原也。苔白如咸者。膜原伏有浊秽也。
【秀按】手少阳经。外主腠理。内主三焦膜原。故《伤寒论》曰。胸中有寒。丹田有热。舌上苔白者。不可攻之。
盖胸中即上焦。丹田即下焦。若有苔白而滑腻及滑浓者。寒饮积聚膈上。伏热积于下焦。但宜苦辛和解。不可
纯攻其里也。故尖白根黄。或根黑。或中黄。或半边苔灰。半边苔白。皆半表半里证。但看白色之多少。白色
多者。表邪尚多。宜和解兼表。张氏柴胡桂姜汤。俞氏柴胡枳桔汤。皆使上焦得通。津液得下。胃气因和。则
津津自汗而解。若黄黑灰多。或生芒刺。或黑点干裂。苔色虽白。纵表邪未尽。而里热已结。急宜和解兼下。
张氏大柴胡汤。俞氏柴胡陷胸汤。正为此设。使其邪从下泄也。若足少阳经。纯乎胆火用事。舌多鲜红。即白
中带红。亦多起刺。急宜和解兼清。俞氏柴胡白虎汤。俞氏蒿芩清胆汤。皆清相火而泄胆热也。
【廉勘】凡寒邪已离太阳之表。未入阳明之里。正手少阳经也。故谓之半表半里。故凡白苔浮滑而带腻带
涨。刮之有净有不净者。乃寒邪已传手少阳经。正半表半里之部分也。故俞氏柴胡枳桔汤。适合此证。若舌苔
粗如积粉。扪之糙涩。刮之不尽。湿热已结于胸膈腹膜之原。故谓之膜原。原指膜中空隙处言。外通肌肉。内
近胃腑。为内外交界之地。实一身之半表半里也。故在外之邪。必由膜原入内。在内之邪。必由膜原达外。吴
又可创制达原饮。具有卓识。惟知母直清阳明之热。白芍疏泄厥阴之火。与少阳经殊未惬合。俞氏去知母白芍
二味。加枳桔柴青四味。较原方尤为精当。盖枳桔轻苦微辛。轻宣上焦。浓朴草果。温通中焦。青皮槟榔。直
达下焦。柴胡达膜以疏解半表。黄芩泻火以清泄半里。使一味甘草以和诸药也。为治湿温时疫初起之良方。即
寻常湿热类疟。用之亦有殊功。惟伏邪内舍于营。由少阴而转出少阳者。如春温证。少火皆成壮火。舌如淡红
嫩红。或白中带红。尚为温病之轻证。一起即纯红鲜红。甚则起剌。此胆火炽而营分化热。则为温病之重证矣。
阳明居里。舌苔正黄。多主里实。黄白相兼。邪犹在经。微黄而薄。邪浅中虚。黄而糙涩。邪已入腑。浅黄
薄腻。胃热尚微。深黄浓腻。胃热大盛。老黄焦黄。或夹灰黑。或起芒刺。胃热已极。黄滑痰火。黄腻湿热。黄而垢
腻。湿热食滞。黄起黑点。温毒夹秽。黄浓不燥。舌色青紫。多夹冷酒。或挟冷食。黄而晦黯。多夹痰饮。或挟寒瘀。
【秀按】苔黄而滑者。为热未结。不可便攻。黄而燥者。为热已盛。峻下无疑。黄而生芒刺黑点者。为热已
极。黄而生瓣裂纹者。为胃液干。下证尤急。亦有根黄浓腻。舌尖白而中不甚干。亦不滑。而短缩不能伸出
者。此胶潺宿食郁伏胃中也。又有苔却黄浓。甚则纹裂。而舌色青紫。舌质不干者。此阴寒夹食也。诸黄苔虽
属胃热。但须分缓急轻重下之。且有佐温佐热佐消佐补之不同。临证者尤宜细辨。
【廉勘】白苔主表。亦主半表半里。黄苔虽专主里。然有带白之分。临证时。但看舌苔带一分白。病亦带一
分表。故黄白相兼。或灰白微黄。慎不可轻投三黄。一味苦泄。其中每有表邪未解。里热先结者。或气分郁
热。或湿遏热伏。虽胸脘痞闷。宜从开泄。宣畅气机以达表。即黄薄而滑。亦为无形湿热。中有虚象。尤宜芳
淡轻化。泄热透表。必纯黄无白。邪方离表而入里。如老黄。或深黄。或焦黄。邪方离经而入腑。然黄色不
一。亦当详辨。试述刘吉人察舌新法以明辨之。（1）正黄色苔。乃胃热正色。为伤寒已传阳明之里。为温病始
传之候。其为湿温温热。当以脉之滑涩有力无力。分别用药。（2）嫩黄色苔。由白而变为黄。为嫩黄色。为胃
浊初升之候。亦为胃阳初醒之候。（3）老黄色苔。为胃阳明盛之候。若浓腐堆起。此饮食浊气上达之候。为湿
温化热之始。为温热灼液之候。（4）牙黄色苔。胃中浊腐之气始升。牙黄无孔。谓之腻苔。中焦有痰也。（5）
水黄色苔。如鸡子黄白相间染成之状。乃黄而润滑。为痰饮停积湿温正候。或为温热病而有水饮者。或热入
胃误服燥药。变生此苔者。宜以脉证分别断之。（6）黄腐苔。苔色如豆渣炒黄堆铺者。下证也。如中有直裂。
气虚也。亦不可下。当补气。以气不足运化也。（7）黄如蜡敷苔。湿温痰滞之候。故苔无孔而腻。（8）黄如虎
斑纹苔。乃气血两燔之候。（9）黄如粟米色苔。颗粒分明。乃胃阳亢盛之候。（10）黄如炒枳壳色苔。为胃阳盛
极。阳亢阴虚之候。胃汁干槁。故苔色如枳壳炒过状。枯而不润。（11）黄如沉香色苔。为胃热极盛。胃液将枯
之候。（12）黄色兼灰色苔。此风温兼湿。阳气抑郁。故苔无正色。先当疏气开郁。（13）黄黑相间如锅焦粑苔。
摸之刺手。看之不泽。为胃中津液焦灼。口燥舌干之候。然有阳气为阴邪所阻。不能上蒸而化津液者。当以脉
诊断之。脉滑有力鼓指者。火灼津也。脉涩无力鼓指者。痰饮瘀血阻抑阳气。不能化生津液也。
太阴主湿。舌多灰苔。甚则灰黑。灰而滑腻。湿重兼寒。灰而淡白。脾阳大虚。灰而糙腻。湿滞热结。灰而
干燥。脾阴将涸。灰生腻苔而舌质粗涩干焦。刮之不能净者。湿竭化燥之热证也。灰黑腻苔而舌质嫩滑湿润。洗
之不改色者。湿重夹阴之寒证也。凡舌苔或灰或黑。或灰黑相兼。病多危笃。切勿藐视。
【秀按】灰如草灰。黑如墨黑。虽同为湿浊阴邪。然舌已结苔。毕竟实热多而虚寒少。除舌灰而润。并无浓
苔。亦不变别色。舌色淡黑。黑中带白舌质滑润者。为阴寒证外。余如黄苔而转灰黑者。不论尖灰尖黑。中灰
中黑。根灰根黑。纯灰色。纯黑色。凡舌质干涩。及生刺点裂纹。起瓣起晕。均为伤寒传经之热证。亦为温热
伤脏之火证。不拘在根在中在尖。均宜急下以存津液。佐消佐补。临证酌用可也。惟夏月中暑。苔多灰黑。或
灰滑浓腻。或黑滑腻浓。均为湿痰郁热。亦不可与传经证同论。如屡下而灰黑不退。屡清而灰黑愈增。其舌或
润或不润。而舌形圆大胖嫩。更有苔不甚燥。而舌心虽黑或灰。无甚苔垢。均为伤阴之虚证。急宜壮水滋阴。
固不得用硝黄。亦不可用姜附。
少阴主热。中藏君火。多属血虚。舌色多红。淡红浅红。血亏本色。深红紫红。血热已极。鲜红灼红。阴虚
火剧。嫩红干红。阴虚水涸。舌红转绛。血液虚极。绛润虚热。绛干燥热。绛而起刺。血热火烈、绛而燥裂。阴伤液竭。
【秀按】心开窍于舌。故舌红为心之正色。舌绛为心之真脏色。真脏脉现者病多危。真脏色现者病尤危。故
不论脉证如何。见绛舌多不吉。凡心经血热则舌正红。色如红花。热毒重则舌深红。色如红缎。热毒尤重则舌
娇红。色如桃花。热毒重而血瘀则舌紫红。色如胭脂。此皆为红色舌。尖红者心火上炎也。根红者血热下烁
也。通红无苔。及似有苔粘腻者。血热又挟秽浊也。红星红斑红裂红碎者。热毒盛极也。红中兼有白苔者。客
寒包火也。红中兼有黑苔者。邪热传肾也。红中夹两条灰色者。湿热兼夹冷食也。红中起白 点者。心热灼肺
也。红中兼黄黑有芒刺者。心热转入胃腑也。若淡红者血虚也。淡红无苔。反微红兼黄白苔者。气不化液也。
甚则淡红带青者。血分虚寒也。惟红色柔嫩。如朱红柿。望之似润。扪之无津者。此为绛色舌。多由汗下太
过。血液告竭。病多不治。张长沙炙甘草汤。用之亦多不及救。
厥阴气化主风。风从火化。舌多焦紫。亦有寒化。舌多青滑。舌见青紫。其病必凶。深紫而赤。肝热络瘀。或
阳热酒毒。淡紫带青。寒中肝肾。或酒后伤冷。
【秀按】舌色见紫。总属肝脏络瘀。因热而瘀者。舌必深紫而赤。或干或焦。因寒而瘀者。舌多淡紫带青。
或滑或黯。他如痰瘀郁久。久饮冷酒。往往现紫色舌。惟紫而干晦。如煮熟猪肝色者。肝肾已坏。真脏色现
也。必死。
【廉勘】肝多络脉而藏血。血色青紫。凡皮肤上现青筋者。皆络脉也。故舌现青紫。确为厥阴肝病之正色。
惟手厥阴包络。其舌仍现红色。
太阳表证初起时，舌头上大多没有苔，且湿润。即使有苔，也是微白而薄，甚至有的苔色淡白。只有那些平时多痰湿的人，舌苔多为白滑。舌色呈淡红色。如果是素来禀赋血热的人，虽然舌苔微白，但舌色反而发红。如果病邪传入本腑（膀胱），导致膀胱蓄水，舌苔多为纯白色且厚浓，但并不干燥粗糙。如果是膀胱蓄热，舌苔多为白色兼微黄色，薄而润滑。
【秀按】太阳经的气化功能主司水液代谢，其本性属寒。寒属于阴邪，白色代表凉象，所以舌苔颜色多为白色。白润、白薄的舌苔，是太阳病的本来征象。如果是白滑的舌苔，说明是风寒兼夹湿气；白滑而腻的舌苔，说明是风寒兼夹湿气并伴有痰饮。苔薄或苔厚，取决于体内痰湿的多少。只有当苔色淡白，白而嫩滑时，才属于素体虚寒的情况。
【廉勘】舌苔色白而薄，确实是寒邪在表的征象。但是，必须是白苔浮滑而薄，刮去后苔又长出来的，才是太阳经表受寒邪。如果是全舌覆盖白苔，浮涨且浮腻，逐渐积聚变干，微厚浓且刮不掉的，这是寒邪将要化火的表现。如果初起时就是白薄而干燥起刺的，这是温病因为感受寒邪而发作，肺津已经受伤。如果舌苔内层薄而粘腻，这是湿邪停留在气分。所以同样是苔色薄白，一种主寒邪在表，一种主气机郁滞不舒，一种主肺津受伤。
少阳经主管半表半里。病偏于半表者，舌头多表现为苔色白滑，或者舌尖苔白，或者单边白，或者两边白。病偏于半里者，舌头多红而苔白，间杂出现其他颜色。比如舌尖白中间红，或者边白中间红，或者尖红中间白，或者尖白根黑，或者尖白根灰。如果白苔多而滑，黄灰苔少，说明半表证较多。红舌多而白苔少，或者夹杂黄色灰色，说明半里证较多。如果舌边白滑润泽，虽然中心黄黑，仍然属于半表半里证。只有当白苔粗厚如积粉，两边色红或紫时，这是温疫伏匿在膜原。苔白像盐霜一样，说明膜原伏有浊秽之气。
【秀按】手少阳经，外主腠理，内主三焦和膜原。所以《伤寒论》说：“胸中有寒，丹田有热，舌上苔白者，不可攻之。”大概胸中即上焦，丹田即下焦。如果有苔白而滑腻及滑厚的，是寒饮积聚在膈上，伏热积聚在下焦。只宜用苦辛法和解，不可单纯攻下里实。所以舌尖白根黄，或者根黑，或者中间黄，或者半边苔灰半边苔白，都属于半表半里证。只要看白色的多少，白色多的，说明表邪尚多，宜用和解兼解表的方法。张氏柴胡桂姜汤，俞氏柴胡枳桔汤，都是使上焦通畅，津液下行，胃气调和，从而自然出汗而解。如果黄黑灰色多，或者生芒刺，或者黑点干裂，苔色虽白，纵然表邪未尽，而里热已结，急宜用和解兼攻下的方法。张氏大柴胡汤，俞氏柴胡陷胸汤，正是为此设立的，使邪气从下面排泄出去。如果是足少阳经，纯粹是胆火发病，舌头多鲜红，即使白中带红，也多起刺，急宜用和解兼清热的办法。俞氏柴胡白虎汤，俞氏蒿芩清胆汤，都是清相火而泄胆热的方子。
【廉勘】凡是寒邪已经离开太阳之表，但未进入阳明之里，这正是手少阳经的病位，所以称为半表半里。所以凡是白苔浮滑而带腻带胀，刮之有净有不净的，乃是寒邪已传入手少阳经，正是半表半里的部分。所以俞氏柴胡枳桔汤，适合此证。如果舌苔粗厚如积粉，摸起来糙涩，刮之不尽，这是湿热已结于胸膈腹膜的膜原。所谓“原”，指膜中空隙处而言，外通肌肉，内近胃腑，是内外交界之地，实际上是一身的半表半里。所以在外的邪气，必由膜原入内；在内的邪气，必由膜原达外。吴又可创制了达原饮，具有卓识。只是知母直清阳明之热，白芍疏泄厥阴之火，与少阳经并不完全契合。俞氏去掉知母、白芍两味药，加上枳壳、桔梗、柴胡、青皮四味药，比原方更为精当。大概枳壳、桔梗轻苦微辛，轻宣上焦；厚朴、草果，温通中焦；青皮、槟榔，直达下焦；柴胡达膜以疏解半表；黄芩泻火以清泄半里；一味甘草以调和诸药。这是治疗湿温时疫初起的良方，即使是寻常湿热类似疟疾，用它也有特殊功效。只有伏邪内舍于营分，由少阴转出少阳的，比如春温证，少火都变成壮火，舌头如淡红、嫩红，或者白中带红，尚为温病的轻证。一旦发病就纯红鲜红，甚至起刺，这是胆火炽盛而营分化热，则为温病的重证了。
阳明居里，舌苔正黄，多主里实证。黄白相间，邪气还在经络；微黄而薄，邪浅中虚；黄而糙涩，邪已入腑；浅黄薄腻，胃热尚微；深黄浓腻，胃热大盛；老黄焦黄，或者夹杂灰黑，或者起芒刺，胃热已极。黄滑是痰火，黄腻是湿热，黄而垢腻是湿热食滞，黄起黑点是温毒夹秽，黄浓不燥，舌色青紫，多夹冷酒，或者挟冷食。黄而晦黯，多夹痰饮，或者挟寒瘀。
【秀按】苔黄而滑，说明热未结实，不可以马上攻下。黄而燥，说明热已盛，峻下无疑。黄而生芒刺黑点的，说明热已极。黄而生瓣裂纹的，说明胃液干枯，下法的指征尤其紧急。也有根部黄浓腻，舌尖白而中间不甚干，也不滑，但舌短缩不能伸出的，这是胶滞的宿食郁伏在胃中。又有苔却黄浓，甚至纹裂，而舌色青紫，舌质不干润的，这是阴寒夹食。各种黄苔虽然都属于胃热，但必须分辨缓急轻重进行攻下，并且有佐以温药、佐以热药、佐以消食药、佐以补益药的不同。临证时尤其应当仔细辨别。
【廉勘】白苔主表，也主半表半里。黄苔虽然专主里，但也有带白的情况。临证时，只看舌苔带一分白，病也就带一分表。所以黄白相间，或者灰白微黄，千万不要轻易投用三黄（黄连、黄芩、黄柏）一味苦寒泄热。其中往往有表邪未解，里热先结的情况，或者是气分郁热，或者是湿遏热伏。虽然胸脘痞闷，宜从开泄，宣畅气机以达表。即使是黄薄而滑，也是无形湿热，中有虚象，尤其适宜用芳香清淡之法轻化，泄热透表。必须纯黄无白，邪气方才离表而入里。如老黄，或者深黄，或者焦黄，邪气方才离经而入腑。然而黄色不一，也应当详细辨别。试述刘吉人察舌新法以明确辨别：（1）正黄色苔，是胃热的正色，为伤寒已传阳明之里，为温病始传的征候。其为湿温温热，应当以脉之滑涩有力无力，分别用药。（2）嫩黄色苔，由白变为黄，为嫩黄色，是胃浊初升的征候，也是胃阳初醒的征候。（3）老黄色苔，是胃阳明盛盛的征候。若浓腐堆起，这是饮食浊气上达的征候，为湿温化热的开始，为温热灼伤津液的征候。（4）牙黄色苔，胃中浊腐之气始升。牙黄无孔，谓之腻苔，说明中焦有痰。（5）水黄色苔，如鸡子黄白相间染成之状，乃黄而润滑，为痰饮停积湿温的正候。或者为温热病而有水饮者，或者热入胃误服燥药，变生此苔者，应当以脉证分别判断。（6）黄腐苔，苔色如豆渣炒黄堆铺者，是下法的指征。如中有直裂，是气虚，也不可下，应当补气，因为气不足运化。（7）黄如蜡敷苔，是湿温痰滞的征候，所以苔无孔而腻。（8）黄如虎斑纹苔，是气血两燔的征候。（9）黄如粟米色苔，颗粒分明，是胃阳亢盛的征候。（10）黄如炒枳壳色苔，为胃阳盛极，阳亢阴虚的征候。胃汁干槁，所以苔色如枳壳炒过状，枯而不润。（11）黄如沉香色苔，为胃热极盛，胃液将枯的征候。（12）黄色兼灰色苔，这是风温兼湿，阳气抑郁，所以苔无正色，先当疏气开郁。（13）黄黑相间如锅焦粑苔，摸之刺手，看之不泽，为胃中津液焦灼，口燥舌干的征候。然而有阳气为阴邪所阻，不能上蒸而化津液的，应当以脉诊断。脉滑有力鼓指者，是火灼津液。脉涩无力鼓指者，是痰饮瘀血阻抑阳气，不能化生津液。
太阴主湿，舌头多现灰苔，甚则灰黑。灰而滑腻，是湿重兼寒；灰而淡白，是脾阳大虚；灰而糙腻，是湿滞热结；灰而干燥，是脾阴将竭。灰生腻苔而舌质粗涩干焦，刮之不能净的，是湿竭化燥的热证。灰黑腻苔而舌质嫩滑湿润，洗之不改色的，是湿重夹阴的寒证。凡是舌苔或灰或黑，或灰黑相兼，病情多危笃，切勿轻视。
【秀按】灰如草灰，黑如墨黑，虽然同为湿浊阴邪，但舌已结苔，毕竟实热多而虚寒少。除了舌灰而润，并无浓苔，也不变别色，舌色淡黑，黑中带白舌质滑润的，属于阴寒证之外，其余如黄苔而转灰黑的，不论尖灰尖黑，中灰中黑，根灰根黑，纯灰色，纯黑色，凡舌质干涩，以及生刺点裂纹，起瓣起晕的，均为伤寒传经的热证，也为温热伤脏的火证。不拘在根在中在尖，均宜急下以存津液，佐以消法或补法，临证酌情使用即可。只有夏月中暑，苔多灰黑，或者灰滑浓腻，或者黑滑腻浓，均为湿痰郁热，也不可与传经证同论。如果屡下而灰黑不退，屡清而灰黑愈增，其舌或润或不润，而舌形圆大胖嫩，更有苔不甚燥，而舌心虽黑或灰，无甚苔垢的，均为伤阴的虚证，急宜壮水滋阴。固然不能用硝黄，也不可用姜附。
少阴主热，中藏君火，多属血虚，舌色多红。淡红浅红，是血亏的本色；深红紫红，是血热已极；鲜红灼红，是阴虚火剧；嫩红干红，是阴虚水涸。舌红转绛，是血液虚极。绛而润是虚热，绛而干燥是实热，绛而起刺是血热火烈，绛而燥裂是阴伤液竭。
【秀按】心开窍于舌，所以舌红为心的正色，舌绛为心的真脏色。真脏脉现者病多危，真脏色现者病尤危。所以不论脉证如何，见绛舌多不吉利。凡是心经血热则舌正红，色如红花；热毒重则舌深红，色如红缎；热毒尤重则舌娇红，色如桃花；热毒重而血瘀则舌紫红，色如胭脂。这些都是红色舌。尖红者是心火上炎；根红者是血热下烁；通红无苔，及似有苔粘腻者，是血热又挟秽浊；红星红斑红裂红碎者，是热毒盛极；红中兼有白苔者，是客寒包火；红中兼有黑苔者，是邪热传肾；红中夹两条灰色者，是湿热兼夹冷食；红中起白点者，是心热灼肺；红中兼黄黑有芒刺者，是心热转入胃腑。若淡红者是血虚；淡红无苔，反微红兼黄白苔者，是气不化液；甚则淡红带青者，是血分虚寒。惟独红色柔嫩，如朱红柿，望之似润，扪之无津的，此为绛色舌，多由汗下太过，血液告竭，病多不治。张长沙炙甘草汤，用之亦多不及救。
厥阴气化主风，风从火化，舌头多焦紫。也有寒化的情况，舌头多青滑。舌见青紫，其病必凶。深紫而赤，是肝热络瘀，或者是阳热酒毒；淡紫带青，是寒中肝肾，或者是酒后伤冷。
【秀按】舌色见紫，总属肝脏络脉瘀滞。因热而瘀者，舌必深紫而赤，或者干或者焦；因寒而瘀者，舌多淡紫带青，或者滑或者黯。其他的如痰瘀郁久，久饮冷酒，往往现紫色舌。惟独紫而干晦，如煮熟猪肝色的，是肝肾已坏，真脏色现，必死。
【廉勘】肝多络脉而藏血，血色青紫。凡是皮肤上现青筋的，都是络脉。所以舌现青紫，确为厥阴肝病之正色。惟独手厥阴心包络，其舌仍现红色。
At the initial stage of Taiyang exterior syndrome, the tongue usually has no coating and is moist. If there is a coating, it is slightly white and thin, or even pale white. Only in those who are prone to phlegm-dampness is the coating mostly white and slippery. The tongue body color is light red. In individuals with a constitution prone to blood heat, although the coating may be slightly white, the tongue body color tends to be red. If the pathogen transmits to its associated fu organ (the Bladder), causing water accumulation in the bladder, the coating is mostly pure white and thick, but not dry or rough. If there is heat accumulation in the bladder, the coating is mostly white mixed with slight yellow, thin and slippery.
[Commentary by Xiu] The Qi transformation of the Taiyang channel governs water metabolism and its nature is originally cold. Cold is a yin pathogen, and white represents a cool image; therefore, the coating color is mostly white. White and moist, or white and thin coatings, represent the original manifestation of this condition. A white and slippery coating indicates wind-cold combined with dampness; a white, slippery, and greasy coating indicates wind-cold combined with dampness and phlegm. Whether the coating is thin or thick depends on the amount of phlegm-dampness in the body. Only when the coating is pale white, white, tender, and slippery does it indicate a constitution of deficiency-cold.
[Commentary by Lian] A white and thin coating indeed indicates cold pathogen at the exterior. However, it must be a floating, slippery, and thin white coating that regrows after scraping to confirm cold pathogen affecting the Taiyang channel exterior. If the entire tongue is covered with a white coating that is floating, swollen, and greasy, gradually accumulating and becoming dry, slightly thick, and difficult to scrape off, this indicates that the cold pathogen is transforming into fire. If at onset the coating is white, thin, and dry with prickles, this indicates warm disease triggered by cold invasion, where lung fluids have been damaged. If the inner layer of the coating is thin and sticky, this indicates damp pathogen residing in the qi level. Thus, although the coating color is thin and white, one case indicates cold pathogen at the exterior, another indicates qi stagnation, and another indicates damage to lung fluids.
The Shaoyang channel governs the half-exterior and half-interior. When the disease leans towards the half-exterior, the tongue mostly shows a white and slippery coating, or white coating only at the tip, or on one side, or on both sides. When the disease leans towards the half-interior, the tongue is mostly red with a white coating, interspersed with other colors. For example, white tip with red center, white edges with red center, red tip with white center, white tip with black root, or white tip with grey root. If the white coating is abundant and slippery, while yellow/grey coatings are scarce, the half-exterior syndrome predominates. If the red tongue body is abundant with little white coating, or mixed with yellow/grey colors, the half-interior syndrome predominates. If the edges are white, slippery, and moist, despite a yellow/black center, it still belongs to the half-exterior/half-interior syndrome. Only when the white coating is coarse like accumulated powder, with red or purple edges, does it indicate warm epidemic pathogen latent in the Mo Yuan (membrane source). A white coating resembling salt frost indicates turbid filth latent in the Mo Yuan.
[Commentary by Xiu] The Hand Shaoyang channel externally governs the interstices (Cou Li) and internally governs the San Jiao and Mo Yuan. Therefore, *Shanghan Lun* states: "If there is cold in the chest and heat in the Dantian, and a white coating on the tongue, do not use purgatives." Roughly, the chest refers to the Upper Jiao, and the Dantian refers to the Lower Jiao. If the coating is white, slippery, and thick, it indicates cold fluid accumulation above the diaphragm and latent heat accumulation in the Lower Jiao. One should only employ bitter-pungent harmonization methods, not purely purge the interior. Thus, a white tip with yellow/black root, or yellow center, or half-grey/half-white coating, all belong to half-exterior/half-interior syndromes. Observing the quantity of white: if white is abundant, exterior pathogen remains significant, so harmonization combined with exterior-resolving is appropriate. Zhang’s Chaihu Guijiang Tang and Yu’s Chaihu Zhijie Tang facilitate the free flow of the Upper Jiao, descent of fluids, and harmony of Stomach Qi, leading to resolution through spontaneous sweating. If yellow/black/grey colors predominate, or if prickles, black spots, or dry cracks appear, even if the coating is white, indicating that although exterior pathogen is not fully resolved, interior heat has consolidated, urgent harmonization combined with purgation is required. Zhang’s Da Chaihu Tang and Yu’s Chaihu Xiantong Tang are designed for this purpose, allowing pathogen to exit from below. If the Foot Shaoyang channel is solely governed by Gallbladder fire, the tongue is mostly bright red; even if white mixes with red, prickles often appear. Urgent harmonization combined with clearing is needed. Yu’s Chaihu Baitou Tang and Yu’s Haoqin Qingdan Tang clear ministerial fire and drain Gallbladder heat.
[Commentary by Lian] Whenever cold pathogen leaves the Taiyang exterior but has not entered the Yangming interior, it resides in the Hand Shaoyang channel, hence termed half-exterior/half-interior. Thus, whenever a white coating is floating, slippery, greasy, and swollen, and scraping yields inconsistent results, it signifies cold pathogen transmitted to the Hand Shaoyang channel, occupying the half-exterior/half-interior sector. Yu’s Chaihu Zhijie Tang is suitable for this syndrome. If the tongue coating is coarse like accumulated powder, rough to touch, and cannot be completely scraped off, it indicates damp-heat has consolidated in the Mo Yuan of the chest, diaphragm, and abdominal membranes. "Yuan" refers to the hollow spaces within the membranes, connecting externally to muscles and internally near the Stomach, serving as the boundary between interior and exterior, effectively the half-exterior/half-interior of the whole body. Hence, external pathogens enter inward via the Mo Yuan, and internal pathogens exit outward via the Mo Yuan. Wu Youke created Daren Yin with profound insight. However, Zhimu directly clears Yangming heat, and Baishao drains Jueyin fire, which does not perfectly align with the Shaoyang channel. Yu removed Zhimu and Baishao, adding Zhike, Jiegeng, Chaihu, and Qingpi, making the formula more precise. Zhike and Jiegeng are lightly bitter and pungent, gently venting the Upper Jiao; Houpo and Caoguo warm and unblock the Middle Jiao; Qingpi and Binglang reach directly to the Lower Jiao; Chaihu reaches the membrane to resolve the half-exterior; Huangqin clears fire to drain the half-interior; Gancao harmonizes the herbs. This is an excellent formula for early-stage damp-warmth and seasonal epidemics, also effective for common damp-heat resembling malaria. However, in cases where latent pathogen resides in the Ying level and emerges from Shaoyin to Shaoyang, such as Spring Warmth, the mild fire transforms into vigorous fire. Tongues appearing light red, tender red, or white-mixed-with-red represent mild warm disease. Sudden onset of pure bright red, even with prickles, indicates blazing Gallbladder fire and heat differentiating in the Ying level, representing severe warm disease.
Yangming resides in the interior; a true yellow coating mostly indicates interior excess. Yellow-white mixture suggests pathogen still in the channels; slight yellow and thin indicates shallow pathogen with middle deficiency; yellow and rough/rough indicates pathogen entered the Fu organs; light yellow and thin/greasy indicates slight Stomach heat; deep yellow and thick/greasy indicates excessive Stomach heat; old yellow or scorched yellow, possibly mixed with grey/black or prickles, indicates extreme Stomach heat. Yellow and slippery indicates phlegm-fire; yellow and greasy indicates damp-heat; yellow and dirty/greasy indicates damp-heat with food stagnation; yellow with black spots indicates warm toxin mixed with filth; yellow, thick, but not dry with blue-purple tongue body indicates retention of cold wine or cold food. Yellow and dull/dark indicates retention of phlegm-fluid or cold-stasis.
[Commentary by Xiu] A yellow and slippery coating indicates heat has not consolidated; purgation should not be used immediately. A yellow and dry coating indicates intense heat; drastic purgation is indicated. Yellow with prickles and black spots indicates extreme heat. Yellow with petal-like cracks indicates dried stomach fluids; the indication for purgation is especially urgent. There are cases where the root is yellow, thick, and greasy, the tip is white, the center is not very dry nor slippery, but the tongue is short and cannot extend; this indicates stubborn food stagnation郁伏 (retained) in the Stomach. There are also cases where the coating is yellow and thick, even cracked, but the tongue body is blue-purple and not dry; this indicates cold combined with food stagnation. Although various yellow coatings belong to Stomach heat, one must distinguish urgency and severity for purgation, and consider adjuvant warming, heating, resolving, or tonifying methods. Clinicians must differentiate carefully.
[Commentary by Lian] White coating governs exterior and also half-exterior/half-interior. Although yellow coating specifically governs interior, it can present with white. In clinical practice, for every point of white on the coating, there is a corresponding point of exterior involvement. Thus, yellow-white mixture, or grey-white with slight yellow, should not be lightly treated with Sanhuang (Coptis, Scutellaria, Phellodendron) alone for bitter cold drainage. Often, exterior pathogen is unresolved while interior heat has consolidated, or there is qi-level stagnant heat, or dampness suppressing heat. Despite chest/epigastric fullness, one should use opening/draining methods to ventilate qi mechanism and reach the exterior. Even thin, slippery yellow coating indicates formless damp-heat with deficiency signs, requiring aromatic/light draining methods to clear heat and vent exterior. Only when the coating is pure yellow without white does the pathogen leave the exterior and enter the interior. Old, deep, or scorched yellow indicates pathogen leaving the channels and entering the Fu organs. However, yellow varies and requires detailed differentiation. Liu Jiren’s new tongue diagnosis method clarifies this: (1) True yellow coating is the normal color of Stomach heat, indicating Shanghan transmitted to Yangming interior, or early transmission in warm disease. For damp-warmth/warm-heat, medication should be differentiated by pulse (slippery/rapid vs. choppy/weak). (2) Tender yellow coating, changing from white to tender yellow, indicates initial rise of Stomach turbidity and awakening of Stomach Yang. (3) Old yellow coating indicates盛 (excess) of Stomach-Yang. If thick and rotting/piling up, it indicates rising of dietary turbidity, beginning of damp-warmth transforming to heat, and burning of fluids by warm-heat. (4) Tooth-yellow coating indicates initial rise of Stomach turbidity. Tooth-yellow without pores is called greasy coating, indicating phlegm in Middle Jiao. (5) Water-yellow coating, resembling chicken egg yolk mixed with white, is yellow and slippery, the correct sign for phlegm-fluid retention in damp-warmth. It may also occur in warm-heat with fluid retention, or after mistakingly taking drying drugs for heat entering Stomach. Differentiate by pulse and symptoms. (6) Yellow putrid coating, resembling fried bean curd residue piled up, indicates purgation is needed. If central vertical cracks exist, it indicates qi deficiency; do not purge, instead tonify qi due to insufficient transportation. (7) Yellow coating like wax paste indicates damp-warmth with phlegm-stagnation; thus no pores and greasy. (8) Yellow coating like tiger stripes indicates simultaneous burning of qi and blood. (9) Yellow coating like millet grains, distinct particles, indicates hyperactive Stomach Yang. (10) Yellow coating like fried Zhiqiao (Aurantii Fructus), indicates extreme Stomach Yang hyperactivity and yin deficiency. Stomach juice is dried; coating resembles fried Zhiqiao, withered and not moist. (11) Yellow coating like agarwood, indicates extreme Stomach heat and impending exhaustion of Stomach fluids. (12) Yellow mixed with grey coating indicates Wind-Warmth combined with dampness, depressed Yang; thus coating lacks normal color; first resolve qi and open depression. (13) Yellow-black mixed like scorched cake, prickly to touch, dull to look, indicates scorching of Stomach fluids, dry mouth/tongue. However, if Yang is blocked by Yin pathogen and cannot vaporize to generate fluids, diagnose by pulse. Slippery, forceful pulse indicates fire burning fluids; choppy, weak pulse indicates phlegm-fluid/stasis blocking Yang, preventing fluid generation.
Taiyin governs dampness; tongue mostly shows grey coating, even black. Grey and slippery/greasy indicates heavy dampness with cold; grey and pale white indicates severe Spleen Yang deficiency; grey and rough/greasy indicates damp stagnation with heat consolidation; grey and dry indicates impending Spleen Yin exhaustion. Grey with greasy coating and rough/dry/scorched tongue body that cannot be cleanly scraped indicates heat syndrome where dampness exhausts and transforms to dryness. Grey-black greasy coating with tender/slipping/moist tongue body that does not change color when washed indicates cold syndrome with heavy dampness and Yin involvement. Whenever coating is grey or black, or mixed, the condition is often critical; do not underestimate it.
[Commentary by Xiu] Grey resembles ash, black resembles ink; although both are damp-turbid yin pathogens, once coating forms, excess-heat is more common than deficiency-cold. Except for grey tongue with moisture, no thick coating, no color change, pale black tongue with white mixed, and slippery tongue body (indicating deficiency-cold), otherwise, yellow turning grey/black, regardless of tip, center, or root being grey/black, pure grey, or pure black, if tongue body is dry/rough, with prickles/cracks, petal-like formations, or halos, these are heat syndromes of Shanghan transmitting through channels, or fire syndromes of warm-heat damaging zang organs. Regardless of location (root, center, tip), urgent purgation is needed to preserve fluids, supplemented by resolving or tonifying methods as clinically appropriate. Only in summer heatstroke is the coating mostly grey/black, or grey slippery/thick, or black slippery/thick, indicating damp-phlegm郁热 (depressed heat); this should not be discussed together with channel-transmission syndromes. If repeated purgation fails to remove grey/black, or repeated clearing increases it, and the tongue is round/large/fat/tender, or coating is not very dry but heart is black/grey with little coating debris, these are deficiency syndromes of Yin injury. Urgently tonify water and nourish Yin. Neither Xiaoshi/Mangxia (Mirabilite/Gypsum) nor Jiang/Fu (Ginger/Aconite) should be used.
Shaoyin governs heat, harboring Minister Fire within, mostly involving blood deficiency; tongue color is mostly red. Light red/shallow red is the natural color of blood deficiency; deep red/purple-red indicates extreme blood heat; bright red/burning red indicates severe yin deficiency with fire; tender red/dry red indicates yin deficiency with fluid exhaustion. Red turning crimson (Jiang) indicates extreme blood deficiency. Crimson and moist indicates deficient heat; crimson and dry indicates excess heat; crimson with prickles indicates fierce blood-fire; crimson with dry cracks indicates yin damage and fluid exhaustion.
[Commentary by Xiu] The Heart opens into the tongue; thus red tongue is the normal color of the Heart, and crimson tongue is the true organ color of the Heart. Appearance of true organ pulse indicates critical illness; appearance of true organ color indicates even more critical illness. Therefore, regardless of pulse/symptoms, seeing a crimson tongue is generally inauspicious. Heart channel blood heat results in true red tongue, color like red flower; heavy heat toxin results in deep red tongue, color like red satin; particularly heavy heat toxin results in delicate red tongue, color like peach blossom; heavy heat toxin with blood stasis results in purple-red tongue, color like rouge. These are all red tongues. Red tip indicates Heart fire flaming upward; red root indicates blood heat scorching downward. Completely red without coating, or seemingly coated and sticky, indicates blood heat mixed with filth. Red stars, spots, cracks, fragments indicate extreme heat toxin. Red mixed with white coating indicates exogenous cold wrapping fire; red mixed with black coating indicates pathogenic heat transmitting to Kidney; red with two grey strips indicates damp-heat mixed with cold food; red with white dots indicates Heart heat burning Lung; red mixed with yellow/black and prickles indicates Heart heat transferring to Stomach Fu. Pale red indicates blood deficiency; pale red without coating, slightly red mixed with yellow/white coating, indicates qi failing to transform fluids; pale red with cyan tint indicates blood-level deficiency-cold. Only red that is tender, like red persimmon, looking moist but feeling dry upon touch, is a crimson tongue, mostly caused by excessive sweating/purging leading to blood exhaustion; illness is often untreatable. Zhang Zhongjing’s Zhi Gancao Tang is often ineffective in saving such cases.
Jueyin Qi transformation governs wind; wind transforms from fire, tongue mostly scorched purple. There is also cold transformation, where tongue is mostly cyan and slippery. Seeing cyan/purple tongue indicates ominous prognosis. Deep purple with red indicates Liver heat and collateral stasis, or yang-heat wine toxicity; pale purple with cyan indicates cold invading Liver/Kidney, or cold injury after drinking alcohol.
[Commentary by Xiu] Purple tongue color always indicates Liver collateral stasis. Stasis due to heat results in deep purple/red tongue, either dry or scorched; stasis due to cold results in pale purple/cyan tongue, either slippery or dark. Other causes include long-term phlegm-stasis stagnation or chronic consumption of cold wine, often presenting purple tongue. Only purple, dry, and dull, resembling cooked pig liver, indicates destruction of Liver/Kidney and appearance of true organ color; death is certain.
[Commentary by Lian] The Liver contains many collaterals and stores blood; blood color is cyan/purple. Any bluish veins visible on skin are collaterals. Thus, cyan/purple tongue is indeed the normal color of Jueyin Liver disease. However, the Hand Jueyin Pericardium channel still presents red tongue.