诊舌之法。既讲形容之条目。当集气色之条目。夫舌者心之官。色者心之华。心生血而属火。色赤而主舌。
是赤者。舌之正色也。故察舌色之变。可知病症之殊也。舌有赤白青黑之色。可分脏腑寒热。色有浅深明
暗之辨。可判虚实死生。推而论之。如赤为热。赤之浅者。虚热也。赤之深者。实热也。青为寒。青之浅者。虚寒
也。青之深者。实寒也。明润而或赤或青则生。枯暗而或赤或青则死。明润之深者。虽病重而可生。枯暗之
浅者。虽病轻而当死。合之形容。亦可知其脏腑也。诸书谓舌红紫者。热也。舌淡白者虚也。舌赤而鲜艳者。
病在血分也。舌中见红赤点。目色黄。头汗。小便不利者。将发黄也。舌见紫斑。身体疼痛。恶寒发热。腮赤者。
将发斑也。舌上赤裂。大渴引饮者。上消之证也。三消病。热甚饮多。舌紫干者。病久则发痈疽而死也。舌赤
起紫泡者。手少阴之热证也。舌纯红露黑纹数条。而苔滑者。水乘火位。寒证也。舌淡红。中见紫黑筋数道
者。厥阴之寒证也。舌灰黑无苔。脉沉迟者。直中三阴也。舌无苔垢而色变者。虚也。舌白无苔而明淡。外证
热者。胃虚也。舌白唇白者。或流血过多。或脾有病也。舌白唾血者。脾蒸也。舌上青黑无刺。而津润者。中寒
也。舌无苔而冷滑者。少阴之寒证也。舌黑少神而润滑者。虚寒也。舌黑无苔而燥者。津液受伤。虚阳上越
也。热病口干舌黑者。死证也。舌变棕黑色者。热病将死也。热病七八日。其脉微细。小便不利。暴加口燥脉
代。舌焦干黑者。死证也。唇舌紫黯青肿者。中毒也。舌见纯紫色者。酒毒也。唇青舌黑如猪腰者。九死一生
也。舌上无苔。如去油腰子者。亡津液。不治之证也。疳病耳边有青脉。舌上有焦点者。不治也。疳渴饮水不
止。舌黑者。死证也。舌肿黑者。心火极也。舌见蓝色者。微可治。深必死。肺气伤也。妊娠面舌俱带白者。寒证
也。妊娠舌色太赤者。热入血分。恐胎堕也。产妇面舌俱赤者。母子俱生也。产妇面舌俱青。口中沫出者。母
子俱死也。产妇面赤舌青者。母活子死也。产妇面青舌赤。口中沫出者。母死子活也。产妇面舌俱白。证逆
色夭者。血气俱虚。亦死证也。产后舌紫黑者。血先死也。病患胸满。唇痿舌青口燥。漱水不欲咽。无寒热。脉
微大来迟。腹不满。其人言我满者。有瘀血也。若夫跌仆而舌青黑者。瘀血内蓄也。痘疹而舌青黑者。疫气
内陷也。痈疽而舌青黑者。毒瓦斯内攻也。中寒而舌青黑者。邪气入脏也。发斑而舌青黑者。胃烂也。痢疾而
舌青黑者。胃腐也。赤子初生时。舌如猪肝者。死证也。舌纯黑者。无不死也。此皆舌色之条目也。辨其色之
明润枯暗。可判其病之顺逆吉凶也。
诊察舌象的方法，既然已经论述了形态描述的条目，就应当汇集气色观察的条目。舌是心的外窍（心之官窍），色泽是心的外在荣华表现。心主生血且五行属火，其色为赤，对应于舌。
因此，红色是舌头的正常本色。所以通过观察舌色的变化，可以了解病症的差异。舌头有赤、白、青、黑等颜色，可以区分脏腑的寒热属性；色泽有浅深、明暗的区别，可以判断虚实证候及生死预后。推演而论，如红色代表热证，红色浅淡者属虚热，红色深重者属实热。青色代表寒证，青色浅淡者属虚寒，青色深重者属实寒。色泽明润而呈赤或青色者主生，枯槁晦暗而呈赤或青色者主死。色泽明润但颜色深重者，虽然病情严重但仍可存活；色泽枯暗但颜色浅淡者，虽然病情轻微却可能死亡。结合形态描述，也可以推断病变所在的脏腑。各类医书认为舌色红紫者属热证，舌色淡白者属虚证。舌色赤红且鲜艳者，病位在血分。舌中见到红赤斑点，伴有目黄、头汗出、小便不利者，即将发生黄疸。舌上出现紫色斑块，伴有身体疼痛、恶寒发热、腮部发红者，即将发生斑疹。舌上赤裂，大渴引饮者，属上消证候。三消病（糖尿病类疾病），热盛饮多，舌紫干燥者，病程长久则会发生痈疽而死。舌赤并起紫色水泡者，属手少阴心经的热证。舌纯红露出数条黑色纹路，且苔滑者，属水气凌犯火位，为寒证。舌淡红，中间可见数道紫黑筋络者，属厥阴肝经的寒证。舌灰黑无苔，脉象沉迟者，属寒邪直中三阴经。舌无苔垢而颜色改变者，属虚证。舌白无苔且明净淡白，外部症状表现为热者，属胃虚。舌白唇白者，或因失血过多，或因脾脏有病。舌白且唾血者，属脾虚蒸腾所致。舌上青黑无刺，且津液润泽者，属中焦寒证。舌无苔且冷滑者，属少阴肾经的寒证。舌黑少神气且润滑者，属虚寒证。舌黑无苔且干燥者，属津液受损，虚阳上越。热病口干舌黑者，属死证。舌变为棕黑色者，属热病将死之兆。热病七八日，脉象微细，小便不利，突然加重口燥、脉代（间歇脉），舌焦干黑者，属死证。唇舌紫黯青肿者，属中毒。舌见纯紫色者，属酒毒。唇青舌黑如猪腰子者，九死一生。舌上无苔，如同去油的腰子者，属亡失津液，为不治之证。疳积病（小儿营养不良）耳边有青脉，舌上有焦点者，属不治。疳积口渴饮水不止，舌黑者，属死证。舌肿胀发黑者，属心火极盛。舌见蓝色者，轻微尚可治疗，深重必死，属肺气受伤。妊娠期间面色与舌色均带白者，属寒证。妊娠期舌色太赤者，属热入血分，恐怕会导致胎堕。产妇面色与舌色均赤者，母子均能存活。产妇面色与舌色均青，口中流涎沫者，母子均会死亡。产妇面赤舌青者，母活子死。产妇面青舌赤，口中流涎沫者，母死子活。产妇面色与舌色均白，证候逆乱、色泽夭折者，属气血俱虚，也是死证。产后舌紫黑者，属血先死（瘀血内阻）。病患胸满，唇萎舌青，口燥，漱水不欲咽，无寒热，脉象微大来迟，腹部不胀满，但患者自述腹满者，属有瘀血。若是跌打损伤导致舌青黑者，属瘀血内蓄。痘疹病出现舌青黑者，属疫气内陷。痈疽病出现舌青黑者，属毒瓦斯内攻。中寒证出现舌青黑者，属邪气入脏。发斑病出现舌青黑者，属胃烂。痢疾出现舌青黑者，属胃腐。新生儿初生时，舌如猪肝色者，属死证。舌纯黑者，无不死亡。以上都是关于舌色的条目。辨别其色泽的明润与枯暗，可以判断疾病的顺逆吉凶。
The method of tongue diagnosis, having discussed the items regarding morphology, should now collect the items regarding qi and color. The tongue is the external orifice of the Heart (the organ of the Heart manifests in the tongue), and color is the external flourishing manifestation of the Heart. The Heart generates blood and belongs to Fire; its color is red, corresponding to the tongue.
Therefore, red is the normal color of the tongue. Thus, by observing changes in tongue color, one can discern differences in pathological conditions. The tongue may exhibit red, white, green/blue, or black colors, which can distinguish the cold and heat attributes of the Zang-Fu organs. Colors have distinctions of lightness/darkness and brightness/dullness, which can judge deficiency/excess syndromes and life/death prognoses. Deduced further, for instance, red indicates Heat syndrome; a light red indicates Deficient Heat, while a deep red indicates Excess Heat. Green/blue indicates Cold syndrome; a light green/blue indicates Deficient Cold, while a deep green/blue indicates Excess Cold. Bright and moist colors, whether red or green/blue, indicate survival; withered and dull colors, whether red or green/blue, indicate death. A bright and moist but deep color, although indicating severe illness, still allows for survival; a withered and dull but light color, although indicating mild illness, may lead to death. Combined with morphological descriptions, the affected Zang-Fu organs can also be inferred. Various medical texts state that a red-purple tongue indicates Heat; a pale-white tongue indicates Deficiency. A red and bright tongue indicates the pathology is in the Blood level. Red-red spots appearing on the tongue, accompanied by yellow eyes, sweating on the head, and difficult urination, indicate impending jaundice. Purple spots appearing on the tongue, accompanied by body pain, aversion to cold and fever, and reddened cheeks, indicate impending macules/rash. Cracked red tongue with intense thirst and desire to drink indicates Shang Xiao (Upper Wasting-Thirst syndrome). In San Xiao diseases (Wasting-Thirst diseases), with intense heat and excessive drinking, a purple and dry tongue indicates that prolonged illness will lead to carbuncles and sores, resulting in death. A red tongue rising with purple blisters indicates a Heat syndrome of the Hand-Shaoyin (Heart) channel. A purely red tongue revealing several black lines, with a slippery coating, indicates Water encroaching upon the Fire position, representing a Cold syndrome. A pale-red tongue with several purple-black veins in the center indicates a Cold syndrome of the Jueyin (Liver) channel. A grey-black tongue without coating and a deep-slow pulse indicates direct invasion of the Three Yin channels. A tongue without coating/fur but with color change indicates Deficiency. A white tongue without coating, bright and pale, with external symptoms of Heat, indicates Stomach Deficiency. A white tongue and white lips indicate either excessive blood loss or disease in the Spleen. A white tongue with spitting blood indicates Spleen steaming. A green-black tongue without prickles, yet moist with fluids, indicates Middle Jiao Cold. A tongue without coating, cold and slippery, indicates a Cold syndrome of the Shaoyin (Kidney) channel. A black tongue lacking spirit/shen but smooth/moist indicates Deficient Cold. A black tongue without coating and dry indicates injury to body fluids and floating upward of Deficient Yang. Dry mouth and black tongue in febrile diseases indicate a fatal syndrome. A tongue turning brownish-black indicates imminent death from febrile disease. In febrile diseases lasting seven to eight days, if the pulse is minute and fine, urination is difficult, sudden worsening of dry mouth and intermittent pulse occurs, and the tongue becomes scorched, dry, and black, it is a fatal syndrome. Purple-dark, cyan, and swollen lips and tongue indicate poisoning. A purely purple tongue indicates alcohol toxicity. Cyan lips and a black tongue resembling a pig's kidney indicate nine deaths and one life (near-fatal). A tongue without coating, resembling a skinned kidney, indicates exhaustion of body fluids and is an untreatable syndrome. Gan disease (pediatric malnutrition) with blue veins behind the ears and focal points on the tongue is untreatable. Gan disease with unquenchable thirst and a black tongue is a fatal syndrome. A swollen and black tongue indicates extreme Heart Fire. A blue tongue is slightly treatable; if deep, it is fatal, indicating injury to Lung Qi. During pregnancy, a face and tongue both showing white indicate a Cold syndrome. During pregnancy, a too-red tongue indicates Heat entering the Blood level, fearing miscarriage. In postpartum women, a red face and tongue indicate both mother and child will survive. In postpartum women, a cyan face and tongue with foamy saliva indicate both mother and child will die. In postpartum women, a red face and cyan tongue indicate the mother lives and the child dies. In postpartum women, a cyan face and red tongue with foamy saliva indicate the mother dies and the child lives. In postpartum women, a white face and tongue with adverse signs and premature fading of luster indicate dual deficiency of Qi and Blood, which is also a fatal syndrome. A purple-black tongue after childbirth indicates blood death (stasis). A patient with chest fullness, withered lips, cyan tongue, dry mouth, rinsing water without swallowing, no aversion to cold or fever, a pulse that is slightly large but slow and delayed, abdominal distension not palpable but subjectively felt, indicates Blood stasis. If trauma causes a cyan-black tongue, it indicates internal accumulation of Blood stasis. If measles/rashes cause a cyan-black tongue, it indicates epidemic Qi sinking inward. If carbuncles/sores cause a cyan-black tongue, it indicates toxic vapors attacking inward. If Middle Cold causes a cyan-black tongue, it indicates pathogenic Qi entering the Zang organs. If macules/rash cause a cyan-black tongue, it indicates rotting of the Stomach. If dysentery causes a cyan-black tongue, it indicates corruption of the Stomach. When a newborn has a tongue like a pig's liver, it is a fatal syndrome. A purely black tongue invariably leads to death. These are all the items regarding tongue color. By distinguishing the brightness/moisture versus withered/dullness of the color, one can judge the favorable/unfavorable and auspicious/inauspicious nature of the disease.