伤寒发黄。何以明之。经曰。湿热相交。民当病瘅。瘅者黄也。单阳而无阴者也。伤寒
至于发黄。为疾之甚也。湿也热也。甚者则发黄。内热已盛。复被火者。亦发黄也。邪
风被火热。两阳相熏灼。其身必发黄。阳明病被火。额上微汗出。小便不利者。必发
黄。是由内有热而被火。致发黄者也。阳明病无汗。小便不利。心中懊 者必发黄。
是由阳明热盛。致发黄者也。伤寒发汗已。身自为黄。所以然者。寒湿在里不解故
也。以为不可下也。于寒湿中求之。是由寒湿致发黄者也。湿亦令黄也。热亦令黄
也。其能辨之乎。二者非止根本有异。而色泽亦自不同。湿家之黄也。身黄如似熏
黄。虽黄而色暗不明也。至于热盛之黄也。必身黄如橘子色。甚者勃勃出。染着衣
正黄如柏。是其正黄色也。由是观之。湿之与热。岂不异哉。大抵黄家属太阴。太阴
者脾之经也。脾者土。黄土色也。脾经为湿热蒸之。则色见于外。必发身黄。经曰。伤
寒脉浮缓。手足自温者。是为系在太阴。太阴当发身黄者是矣。热虽内盛。若已自
汗出。小便利者。则不能发黄必也。头汗出。身无汗。剂颈而还。小便不利。渴饮水浆。
此为瘀热在里。身必发黄。黄家为热盛。而治法亦自有殊。伤寒八九日。身如橘子
色。小便不利。少腹满者。茵陈蒿汤主之。此欲泄涤其热也。伤寒身黄发热者。栀子
柏皮汤主之。此欲解散其热也。伤寒瘀热在里。身必发黄。麻黄连翘赤小豆汤主
之。此欲解散其热也。此数者。泄涤解散。乃治之不同。亦皆析火彻热之剂也。一或
身黄脉沉结。少腹硬而小便自利。其人如狂者。又为蓄血在下焦。使之黄也。必须
抵当汤下之而愈。黄家既是病之已极。是以有不治之者多矣。非止寸口近掌无
脉。鼻气出冷。为不治之疾。又若形体如烟熏。直视摇头者。是为心绝。环口黧黑。柔
汗发黄。是为脾绝。皆不治之症。医者更详视之。
伤寒病出现发黄症状，该如何阐明其机理呢？《内经》说：“湿热相互交结，民众就会患黄疸病。”“瘅”就是黄的意思，这是指只有阳热而无阴寒的证候。
伤寒发展到出现发黄，说明病情已经很严重了。无论是湿邪还是热邪，严重时都会导致发黄。如果体内热势已经亢盛，又误用火疗（如艾灸、火熏等），也会引起发黄。外感风邪又遭受火热之邪侵袭，两阳相熏灼，身体必然发黄。阳明病若被火疗所伤，仅额头微微出汗，小便不通利的，必定会发黄。这是由于内有热邪又受火攻，从而导致发黄的。阳明病若无汗，小便不利，心中烦闷懊恼的，也必定会发黄。这是由于阳明热盛，从而导致发黄的。
伤寒经过发汗治疗后，身体依然发黄，之所以这样，是因为寒湿在体内未能解除的缘故。这种情况认为不可使用下法，应当在温化寒湿中寻求治法。这是由寒湿导致的发黄。湿邪能使人发黄，热邪也能使人发黄，能够辨别它们吗？这两者不仅根本病因不同，而且面色色泽也有区别。患有湿病的人发黄，身体黄色像被烟熏过一样，虽然黄但色泽晦暗不明。至于热盛导致的发黄，身体黄色一定像橘子皮的颜色，严重的甚至颜色鲜亮耀眼，染着衣服正黄如柏树皮那样，这才是纯正的黄色。由此看来，湿与热，难道不相同吗？
大体上，黄病归属于太阴经，太阴经是脾的经脉。脾属土，对应黄土色。脾经受湿热蒸腾，则黄色显现于体表，必然发生身黄。《内经》说：“伤寒脉象浮缓，手足自然温暖的，这是病系于太阴。太阴病应当发生身黄的，就是这个道理。”热邪虽然在内亢盛，但如果患者已经自汗出，小便通利的，那么就不会发黄。如果是仅头部出汗，身上无汗，汗止于颈部以下，小便不利，口渴想喝水浆，这是瘀热郁结在体内，身体必然发黄。
黄病患者属于热盛，但治疗方法也自有不同。伤寒病程八九日，身体像橘子色，小便不利，小腹胀满的，用茵陈蒿汤主治。这是为了泄涤体内的热邪。伤寒身体发黄且发热的，用栀子柏皮汤主治。这是为了解散体内的热邪。伤寒瘀热郁结在体内，身体必然发黄的，用麻黄连翘赤小豆汤主治。这也是为了解散体内的热邪。这几个方剂，有的泄涤，有的解散，治疗虽有不同，但都属于清泻火热、透达热邪的药剂。
如果一旦身体发黄，脉象沉结，小腹硬满而小便自利，其人神志狂乱如狂的，这又是蓄血在下焦，导致身体发黄。必须用抵当汤攻下才能痊愈。黄病患者既然是病情已至极点，所以有很多是不治之症了。不仅仅是寸口脉搏微弱近于消失，鼻气出冷，属于不治之疾；还有如果形体像烟熏一样黑，两眼直视摇头的，这是心气绝；口唇周围发黑，出冷汗且发黄的，这是脾气绝。这些都是不治之症。医生们更应详细审视这些情况。
Jaundice in Cold Damage. How to elucidate it? The Classic says: "When dampness and heat interact, the people will suffer from Dan jaundice." "Dan" means yellow; this refers to a syndrome characterized by excess Yang-heat without Yin-cold.
When Cold Damage progresses to manifest jaundice, it indicates that the disease is severe. Whether caused by dampness or heat, when either becomes excessive, jaundice ensues. If internal heat is already flourishing and fire therapy (such as moxibustion or fire fumigation) is applied subsequently, jaundice will also occur. When pathogenic wind is combined with fire-heat, the two Yang pathogens scorch each other, and the body must develop jaundice. In Yangming disease, if subjected to fire therapy, with only slight sweating on the forehead and difficulty in urination, jaundice is inevitable. This results from internal heat exacerbated by fire attack. In Yangming disease, if there is no sweating, difficulty in urination, and mental restlessness with regret (Ao Nao), jaundice is also inevitable. This results from flourishing heat in the Yangming channel.
After sweating treatment for Cold Damage, if the body remains yellow, the reason is that cold-dampness remains unresolved within. It is considered inadvisable to use purgation here; instead, one should seek treatment by resolving cold-dampness. This type of jaundice is caused by cold-dampness. Both dampness and heat can cause jaundice; can they be distinguished? Not only are their fundamental causes different, but their complexion colors also differ. In patients with dampness, the yellowing resembles smoke-staining; although yellow, the color is dull and obscure. In contrast, jaundice due to excessive heat presents with a skin color like orange peel; in severe cases, the brightness is striking, staining clothes a true yellow akin to Phellodendron bark. Thus, are not dampness and heat distinct?
Generally, jaundice belongs to the Taiyin system. Taiyin corresponds to the Spleen meridian. The Spleen corresponds to Earth, whose color is yellow. When the Spleen meridian is steamed by damp-heat, the yellow color manifests externally, resulting in generalized jaundice. The Classic states: "In Cold Damage, if the pulse is floating and slow, and the hands and feet are naturally warm, the disease is associated with Taiyin. Taiyin disease should manifest generalized jaundice." Although internal heat may be flourishing, if the patient has spontaneous sweating and free urination, jaundice will not occur. However, if there is sweating only on the head, no sweating on the body (stopping at the neck), difficulty in urination, and thirst for fluids, this indicates stagnant heat trapped inside, and jaundice is inevitable.
Although jaundice patients exhibit excessive heat, treatment methods vary. In Cold Damage lasting eight or nine days, if the body is orange-yellow, urination is difficult, and the lower abdomen is full, Yinchen Hao Tang (Artemisiae Scopariae Decoction) is the primary prescription. This aims to purge and wash away the heat. If Cold Damage presents with jaundice and fever, Zhizi Bopi Tang (Gardeniae Cortex Phellodendri Decoction) is used. This aims to dissipate the heat. If Cold Damage involves stagnant heat trapped inside leading to jaundice, Mahuang Lianqiao Xiaochidou Tang (Ephedra, Forsythia, and Red Bean Decoction) is used. This also aims to dissipate the heat. These prescriptions employ purging or dissipating methods; though different, they all belong to agents that clear fire and penetrate heat.
However, if the body is yellow, the pulse is deep and knotted, the lower abdomen is hard, urination is free, and the person appears manic-like, this indicates blood stasis in the Lower Jiao causing jaundice. Dandang Tang (Ephedra, Cinnamon Twig, Peony, and Ground Beetle Decoction) must be used to purge the condition for recovery. Since jaundice represents an extreme stage of disease, many cases are incurable. Not only are conditions such as the absence of pulse near the crease of the wrist and cold breath from the nose considered incurable; furthermore, if the body appears dark like smoke-stained, with fixed staring and head shaking, this indicates Heart Qi exhaustion. If the area around the mouth turns blackish and sweat is soft/clammy while jaundiced, this indicates Spleen Qi exhaustion. All these are incurable syndromes. Physicians must examine these details carefully.