舌青，或青紫而冷滑者，为寒证。青紫而焦燥，或胀大，或卷缩者，为热证。
寒甚亦卷缩，筋脉得寒而收引也，然必不焦燥。
凡舌强硬短缩，而神气昏乱，语言不清者死。（亦有痰证而舌本硬及缩者，不在此论。）热病，
舌本烂，热不止者死。阴阳易病，舌出数寸者死。伤寒热止在表者，舌无胎。热邪
传里，则胎渐生，由白而黄而黑，由润而燥，而拆裂，由滑而涩、而芒刺，皆以热
之浅深微甚为层次。（胎因内热，致脾气闭滞不行，饮食津液停积于内，故胎见于外。
若脾气不滞，则饮食
运化，津液流通，虽热甚，不必有胎也。此理宜知。）略具如下∶
纯白舌 伤寒白滑胎舌，为热初入内，犹带表证，表剂中加清凉之品。又有胃
中虚冷，寒饮结聚膈上，成白滑胎者。又脾闭甚，则白如积雪。又有脏结证，（详《伤
寒论近言》。而胎白滑者，须辨。温热病，一发便壮热烦渴，舌正赤而有白胎者，
虽滑，即当用白虎，治其内热而表自解，切不可用表药。时疫初起，胎白如积粉。
白杂色舌 伤寒热入胃，则白胎中黄，白多黄少而滑，尚带表证，仍宜于解表
药中加清凉之品。黄多白少，干涩，无表证者，或清或下。（有夹食痰血而滑，须下者，参下
黄杂色舌条。）若燥裂生芒刺，则必下无疑。温热时疫，则虽润滑，亦宜凉膈、白虎、承
气之属，以清热攻里，万不可发表也。
纯黄舌 润滑者须审，若热尚未结聚，不可便攻。若在夏月，便宜攻下，不必
待胎燥乃攻也。
黄杂色舌 根黄硬，尖白，中不甚干，亦不滑，短缩不能伸出，谵妄烦乱者，
此挟痰食，大承气加生姜、半夏治之。舌色青紫，而胎却黄浓，甚则纹裂，但觉口
燥，舌仍不干者，此阴证挟食也。脉或沉细而伏，或虚大而涩，按其心下或脐旁硬
痛，而时失气者，急宜大承气，另煎生附子，佐大黄下之。脉虚大者，黄龙汤下之。
热极烦躁者，更加生地、麦冬，夏月尤宜。此证若胎黄不燥，在冬月，宜附子理中
汤合小承气汤下之。大抵舌有积胎，虽见阴象，亦是虚中有实，急当攻下，但与常
法不同耳。又中宫有痰饮水血者，舌多不燥，不可因其不燥，而延缓至误也。
（中暑证夹血，多有中心黑润者，勿误作阴证治之。）
纯黑舌 遍舌黑胎，夏月或可救，以炎令邪火内外燔灼，黑胎易生也，犹可攻
治。冬月得此舌，必死。
黑杂色舌 中黑边黄，承气下之。边白，大柴胡下之。若生芒刺裂瓣，不论边
系何色，但看瓣底色红活者，急下之。如俱黑者，不治。若腐烂卷缩，亦不治。发
生虫，虽为湿，亦属肝伤，俱为危候。大抵尖黑尚轻，根黑则重。夏月中暑，多
黑舌，边红中黑干者，宜白虎汤。以上皆邪热实热，然亦有虚热者。舌心虽黑或灰
黑，而无积胎，舌形枯瘦，而不甚赤，其证烦渴，耳聋，身热不止，大便五六日或
十余日不行，腹不硬满，按之不痛，神不昏，不得睡，稍睡或呢喃一二句，或带笑，
或叹息，此为津枯血燥之虚热，宜大料六味丸合生脉散、炙甘草汤。误与承气必死。
若直中寒证，始病不发热，舌心便黑色，（非由自黄变化。）虽黑而滑，舌亦瘦小，当
急温之。
赤色舌 温热时疫，热毒内盛，润滑者未可便下，黄连解毒、白虎等汤。干而
有黄白黑等胎，及芒刺、纹裂、坑烂、起 者，皆下证也。一种柔嫩如新生，望之
似润，而燥涸殆甚者，为妄行汗下，津液竭所致，多不治，宜生脉散等。又红痿舌，
（痿软不能动也。）及红细枯长舌，并难治。
紫色舌者，兼酒毒所致，其色必深紫而赤，且干涸。若淡紫而带青滑，则又为
直中寒证矣，须辨。
灰色、（有寒有热。）酱色、（焦黄为酱色，夹食热证也。）蓝色、（木克土败之色。）及妊
娠各舌，（面赤
舌青，子死母活，俱青则俱死，宜润泽，忌枯败。）并当详审。
总之，舌胎不论何色，但干燥者必属热，惟润滑者须审。
舌色发青，或青紫且舌面寒冷湿滑的，属于寒证。舌色青紫且焦躁干燥，或者舌体肿胀增大，或者卷曲缩短的，属于热证。
寒邪极盛也会导致舌体卷缩，这是因为筋脉受寒而收缩牵引所致，但此时舌面必定不焦躁干燥。
凡是舌体强硬、短缩，且精神昏乱、言语不清的，预后不良（主死）。（也有痰证导致舌根僵硬及短缩的情况，不在此列讨论。）热病中，舌体溃烂，且热势不退的，预后不良（主死）。阴阳易病（伤寒愈后因房事复发的疾病），舌体伸出数寸长的，预后不良（主死）。伤寒热邪仅在表层的，舌面上没有苔垢。热邪传入体内，则舌苔逐渐生成，由白色转为黄色再转为黑色，由湿润转为干燥，进而出现裂纹，由滑腻转为涩滞并长出芒刺，这些都是根据热邪深浅轻重的程度来划分的层次。（舌苔是因为内部热盛，导致脾气闭阻停滞，饮食津液停积在体内，所以舌苔显现于外。如果脾气不滞塞，则饮食运化正常，津液流通顺畅，即使热势很盛，也不一定会有舌苔。这个道理应当知晓。）大致情况如下：
纯白舌：伤寒病中出现白滑苔的舌，说明热邪刚初入体内，还带有表证，应在解表药中加入清凉药物。又有胃中虚冷，寒饮结聚在膈上，形成白滑苔的。还有脾脏闭阻严重的，舌苔白得像积雪一样。又有脏结证（详见《伤寒论近言》），若舌苔白滑者，需要仔细辨别。温热病，一发病就高热烦渴，舌质正红而有白苔的，即使舌苔滑润，也应当使用白虎汤，治疗其内热而表证自然解除，切不可使用解表药。时疫初起时，舌苔白得像堆积的粉末。
白杂色舌：伤寒热邪入胃，白苔中夹杂黄色，白多黄少且滑润的，尚带表证，仍适宜在解表药中加入清凉药物。黄多白少，干燥涩滞，无表证的，或用清法，或用下法。（若有夹带食积、痰浊、瘀血而舌苔滑润，需要用下法的，参考下文“黄杂色舌”条。）如果舌苔干燥开裂并长出芒刺，则必须用下法无疑。温热病和时疫，即使舌苔润滑，也宜用凉膈散、白虎汤、承气汤之类的方剂，以清热攻里，万万不可发表。
纯黄舌：舌苔润滑的须仔细审察，如果热邪尚未结聚，不可立即攻下。若在夏季，便适宜攻下，不必等到舌苔干燥才攻下。
黄杂色舌：舌根部黄硬，舌尖白，中部不甚干燥也不滑润，舌体短缩不能伸出，胡言乱语烦躁混乱的，这是挟带痰食，用大承气汤加生姜、半夏治疗。舌色青紫，但舌苔却黄浓，甚至出现裂纹，只感觉口燥，但舌面并不干的，这是阴证挟带食积。脉象或沉细而伏，或虚大而涩，按压心下或脐旁有硬痛感，且时常放屁的，急宜用大承气汤，另煎生附子，佐助大黄攻下。脉象虚大的，用黄龙汤攻下。热极烦躁的，再加生地、麦冬，夏季尤其适宜。此证如果舌苔黄但不干燥，在冬季，宜用附子理中汤合小承气汤攻下。大抵舌上有积滞之苔，虽然见到阴寒之象，也是虚中有实，急当攻下，只是与常规治法不同罢了。又有中焦有痰饮、水气、瘀血的，舌苔多不干燥，不可因为舌苔不干燥，就拖延延误时机。
（中暑证夹带瘀血的，多有舌中心黑而润泽的，不要误作阴证治疗。）
纯黑舌：全舌黑苔，夏季或许还可救治，因为炎热季节邪火内外燔灼，黑苔容易生成，还可以攻治。冬季出现这种舌象，必死无疑。
黑杂色舌：舌中黑边黄，用承气汤攻下。舌边白，用大柴胡汤攻下。如果长出芒刺裂瓣，不论边缘是什么颜色，只看瓣底颜色红活鲜润的，急用下法。如果全是黑色的，无法救治。如果舌体腐烂卷缩，也无法救治。舌上生出虫状物，虽然是湿气所致，但也属于肝伤，都是危重证候。大抵舌尖黑较轻，舌根黑则较重。夏季中暑，多有黑舌，舌边红中间黑干的，宜用白虎汤。以上都是邪热实热，但也有虚热的情况。舌心虽黑或灰黑，但没有积滞之苔，舌形枯瘦，且不太红赤，症状表现为烦渴、耳聋、身热不退，大便五六天或十几天不通，腹部不硬满，按压不痛，神志不昏迷，无法入睡，稍睡或说一两句话呢喃，或带笑，或叹息，这是津枯血燥的虚热，宜用大量六味丸合生脉散、炙甘草汤。误用承气汤必死。如果是直中寒证，起病时不发热，舌心便呈黑色（不是由黄色变化而来），虽然黑但滑润，舌体也瘦小，应当紧急温补。
赤色舌：温热病和时疫，热毒内盛，舌苔润滑的不可立即攻下，可用黄连解毒汤、白虎汤等。干燥且有黄、白、黑等苔，以及芒刺、裂纹、坑烂、起刺的，都是下法适应证。还有一种柔嫩如新生，看起来似乎润泽，但实际上干燥枯竭极其严重的，是妄行汗法或下法，导致津液枯竭所致，大多不治，宜用生脉散等。还有红痿舌（舌体痿软不能活动），以及红细枯长舌，都难治。
紫色舌：兼有酒毒导致的，颜色必深紫而赤，且干燥枯竭。如果是淡紫而带青滑的，则是直中寒证，须仔细辨别。
灰色（有寒有热）、酱色（焦黄为酱色，夹带食积的热证）、蓝色（木克土败坏的颜色）以及妊娠各舌（面赤舌青，胎儿死母亲活；舌色俱青则母子俱死；宜润泽，忌枯败），都应当详细审察。
总之，舌苔不论什么颜色，只要干燥的必定属热，只有润滑的须仔细审察。
The tongue appears cyan, or cyan-purple and cold with a slippery coating, indicating a Cold syndrome. If the tongue is cyan-purple with a scorched and dry surface, or swollen and enlarged, or curled and shortened, it indicates a Heat syndrome.
Extreme Cold can also cause the tongue to curl and shorten because sinews and vessels contract when exposed to Cold; however, the surface will certainly not be scorched and dry.
If the tongue is stiff, short, and shortened, accompanied by mental confusion and unclear speech, the prognosis is fatal. (Note: There are cases of Phlegm syndromes where the root of the tongue is stiff and shortened, which are excluded from this discussion.) In Heat diseases, if the tongue body ulcerates and the heat does not subside, the prognosis is fatal. In Yin-Yang Exchange disease (a relapse after recovery from Shanghan due to sexual activity), if the tongue protrudes several inches, the prognosis is fatal. In Shanghan, if the heat is confined to the exterior, there is no coating on the tongue. When pathogenic Heat transmits inward, the coating gradually forms, changing from white to yellow to black, from moist to dry, then cracking, becoming rough instead of slippery, and developing prickles. These changes represent levels corresponding to the depth and severity of the Heat. (The coating arises because internal Heat causes the Spleen Qi to become obstructed and stagnant; dietary fluids and Jingye accumulate internally, manifesting as a coating externally. If Spleen Qi is not stagnant, digestion proceeds normally, and Jingye circulates freely; even with severe Heat, a coating may not form. This principle should be understood.) The details are as follows:
Pure White Tongue: In Shanghan, a tongue with a white and slippery coating indicates that Heat has just entered the interior but still retains exterior symptoms; cooling herbs should be added to exterior-releasing formulas. Another cause is deficiency-cold in the Stomach, where cold-fluid retention accumulates above the diaphragm, forming a white slippery coating. Severe closure of the Spleen can result in a coating white as accumulated snow. In Zang-Jie syndrome (detailed in *Shanghan Lun Jin Yan*), a white slippery coating requires careful differentiation. In Warm-Heat diseases, if high fever and thirst appear immediately upon onset, with a red tongue body and white coating, even if slippery, Baihu Tang (White Tiger Decoction) should be used to clear internal Heat, resolving the exterior spontaneously; exterior-releasing drugs must absolutely not be used. At the initial stage of seasonal epidemics, the coating may be white like piled powder.
White Mixed-Color Tongue: In Shanghan, when Heat enters the Stomach, the white coating turns yellow. If white predominates over yellow and the coating is slippery, exterior symptoms persist, and exterior-releasing formulas with cooling herbs are appropriate. If yellow predominates over white, and the coating is dry and rough without exterior symptoms, either clearing or purging methods may be used. (If there is retained food, phlegm, or blood stasis causing a slippery coating requiring purging, refer to the "Yellow Mixed-Color Tongue" section below.) If the coating is dry, cracked, and develops prickles, purging is undoubtedly required. In Warm-Heat diseases and epidemics, even if the coating is slippery, formulas such as Liangge San (Cool the Diaphragm Powder), Baihu Tang, or Chengqi Tangs should be used to clear Heat and purge the interior; releasing the exterior is strictly contraindicated.
Pure Yellow Tongue: A slippery coating requires careful examination. If Heat has not yet consolidated, purging should not be performed immediately. However, in summer, purging is appropriate without waiting for the coating to become dry.
Yellow Mixed-Color Tongue: If the root is yellow and hard, the tip is white, the center is neither very dry nor slippery, the tongue is short and cannot extend, and the patient exhibits delirium and restlessness, this indicates concurrent Phlegm and Food Retention; Da Chengqi Tang (Major Order the Qi Decoction) with Shengjiang (Fresh Ginger) and Banxia (Pinellia Rhizome) should be used. If the tongue color is cyan-purple but the coating is thick and yellow, with cracks, and the patient feels dry mouth but the tongue surface is not dry, this is a Yin syndrome with Food Retention. The pulse may be deep, fine, and hidden, or deficient, large, and rough. If pressing the epigastrium or around the umbilicus reveals hardness and pain, accompanied by frequent passage of gas, Da Chengqi Tang should be used urgently, with Sheng Fuzi (Raw Aconite Root) decocted separately to assist Dahuang (Rhubarb Root and Rhizome) in purging. If the pulse is deficient and large, Huanglong Tang (Yellow Dragon Decoction) should be used. For extreme Heat with restlessness, add Shengdi (Rehmannia Root) and Maidong (Ophiopogon Tuber), especially suitable in summer. If the coating is yellow but not dry, in winter, Fuzi Lizhong Tang (Aconite Regulate the Middle Decoction) combined with Xiao Chengqi Tang (Minor Order the Qi Decoction) should be used for purging. Generally, an accumulated coating, even if Yin signs are present, indicates deficiency with excess; urgent purging is required, though the method differs from standard practice. Furthermore, if there is Phlegm-fluid, water, or blood stasis in the Middle Jiao, the coating is often not dry; one must not delay treatment due to the lack of dryness. (In Summerheat syndrome with blood stasis, the center of the tongue is often black and moist; do not mistake this for a Yin syndrome.)
Pure Black Tongue: A whole tongue covered with black coating might be salvageable in summer, as intense heat causes pathogenic Fire to scorch internally and externally, facilitating black coating formation, allowing for purgative treatment. In winter, this sign indicates certain death.
Black Mixed-Color Tongue: If the center is black and the edges yellow, use Chengqi Tang for purging. If the edges are white, use Da Chaihu Tang (Major Bupleurum Decoction) for purging. If prickles and fissures develop, regardless of edge color, if the base of the fissures is red and vibrant, urgent purging is required. If the entire tongue is black, it is untreatable. If the tongue is ulcerated and curled, it is also untreatable. If worm-like projections appear, although caused by Dampness, it indicates Liver injury and is a critical condition. Generally, blackness at the tip is mild, while blackness at the root is severe. In summer, Summerheat often presents with black tongues; if the edges are red and the center is black and dry, Baihu Tang is indicated. All the above describe Excess Heat, but Deficient Heat also exists. If the tongue center is black or gray-black without an accumulated coating, the tongue shape is withered and thin, and not very red, accompanied by irritability, thirst, deafness, persistent fever, constipation for five to ten days, non-distended abdomen without tenderness on palpation, unconfused spirit, insomnia, muttering when sleeping slightly, smiling, or sighing, this is Deficient Heat due to exhaustion of Jingye and drying of Blood. Large doses of Liuwei Wan (Six-Ingredient Pill with Rehmannia) combined with Shengmai San (Generate the Pulse Powder) and Zhigancao Tang (Honey-Fried Licorice Decoction) are appropriate. Misuse of Chengqi Tang will lead to death. If Cold strikes directly, without initial fever, the tongue center becomes black (not changing from yellow), and although black, it is slippery and the tongue is small and thin; urgent warming is required.
Red Tongue: In Warm-Heat diseases and epidemics, with intense internal Heat toxicity, a slippery coating means purging is not yet appropriate; Huanglian Jiedu Tang (Coptis Decoction to Relieve Toxicity) or Baihu Tang may be used. If dry with yellow, white, or black coatings, along with prickles, cracks, pits, ulcers, or raised spots, these are indications for purging. Another type appears tender like new tissue, seemingly moist but actually severely dried out, caused by improper sweating or purging leading to fluid exhaustion; this is mostly untreatable, and Shengmai San is recommended. Red Wei Tongues (tongues that are flaccid and immobile) and red, thin, withered, and elongated tongues are also difficult to treat.
Purple Tongue: Caused by concurrent alcohol toxicity, the color is deep purple and red, and dry. If pale purple with cyan slipperiness, it indicates direct invasion by Cold; careful differentiation is needed.
Gray (can be Cold or Heat), Jiang-color/Jam-color (scorched yellow, indicating Heat with Food Retention), Blue (color of Wood overcoming Earth and failure), and various tongues during pregnancy (red face with cyan tongue indicates fetal death with maternal survival; cyan in both indicates death for both; moisture is favorable, witheredness is unfavorable) all require detailed examination.
In summary, regardless of the coating color, dryness always indicates Heat; only slipperiness requires careful scrutiny.