经络热盛，迫血妄行，出于鼻者，为衄血也。是虽热，其邪尤在经，然亦不可发汗。经曰以桂
枝、麻黄治衄，非治衄也，乃欲散其经中邪气耳。衄血故为欲解，
若衄不止而头汗出，其身无汗，及发热，汗不至足者，又为恶证，当明辩之。
太阳证衄血及服桂枝汤后致衄者，为欲解也，属犀角地黄汤；衄不止。茅花汤。无汗能食者，
即欲衄，黄芩汤。
衄家不可发汗，汗出必额上陷，脉紧急，直视不能 ，不得眠，芍药地黄汤。
阳明病，渴欲漱水不咽者必衄，黄芩芍药汤。
不因下而自利加衄者，麻黄升麻汤。脉浮大，欲发热，下利，鼻衄干呕者，黄芩芍药。衄，烦
而后渴欲饮水，水入即吐，先服五苓散，次服竹叶石膏汤。
少阴病，但厥无汗，强发之，必动其血，或从口鼻，或自目出，名下厥上竭，为难治，当归四
逆汤，仍灸太溪、三阴交、涌泉。一法用黑锡丹。
诸阳受热，其邪在表，当汗不汗，致使热毒入脏，积瘀于内，遂成吐血。凡见眼闭目红，神昏
语短，眩冒迷妄，烦躁漱水，狂惊谵语，鼻衄唾红，背冷足寒，
四肢厥逆，胸腹急满，大便黑利，小便频数，皆瘀血证也。不必悉具，但见一二，便作血证主张。
初得此病，急宜用药。至于陆续不已，经数时而腹痛者，此又难于料理也。
经曰∶服桂枝汤吐者，其后必吐脓血，犀角地黄汤。大下后寸脉沉迟，尺脉不至，咽喉不利，
唾脓血者，麻黄升麻汤。此有两证，一阳毒，一阴毒。阳毒用升麻汤，阴毒用甘桔汤加半夏、生姜。
血热者，黄连阿胶汤、地榆柏皮汤、三黄泻心汤。
脉浮，发热，反灸之，必咽燥吐血，救逆汤。
咽喉闭塞，不可发汗，发汗则吐血，气欲绝，手足厥冷，蜷卧不能自温，当归四逆汤。
经络中热邪炽盛，逼迫血液不循常道而妄行，从鼻腔流出，称为衄血。虽然这是热证，但病邪仍然停留在经络层面，此时也不可以使用发汗法治疗。经典著作指出，使用桂枝汤、麻黄汤来治疗衄血，并非直接治疗出血本身，而是为了疏散经络中的邪气。衄血后病情往往有向愈的趋势；但如果衄血不止且仅头部出汗，身体其他部位无汗，并伴有发热，或者出汗无法到达足部，这属于恶候（危重证候），必须仔细辨别。
太阳病证出现衄血，以及服用桂枝汤后导致衄血的，属于病情欲解之象，适用犀角地黄汤；若衄血不止，可用茅花汤。若无汗且能进食，说明即将发生衄血，适用黄芩汤。
素有衄血病史的人（衄家）不可发汗，如果误用发汗法导致出汗，必然出现额部凹陷、脉象紧急、两眼直视不能转动、无法入睡等症状，适用芍药地黄汤。
阳明病中，口渴想含水漱口但不愿咽下的，必定会发生衄血，适用黄芩芍药汤。
没有经过攻下治疗而自行腹泻并伴有衄血的，适用麻黄升麻汤。脉象浮大，想要发热，伴有腹泻、鼻衄和干呕的，适用黄芩芍药汤。出现衄血，先感到烦躁，随后口渴想饮水，但水喝进去就吐出的，应先服用五苓散，接着服用竹叶石膏汤。
少阴病，仅有四肢厥冷而无汗，如果强行发汗，必然扰动血液，血液或从口鼻流出，或从眼睛流出，这种证候称为“下厥上竭”，属于难治之症，适用当归四逆汤，同时艾灸太溪穴、三阴交穴、涌泉穴。另一种方法是用黑锡丹。
诸阳经感受热邪，病邪在体表，应当发汗却未能及时发汗，致使热毒内传入脏，瘀积于体内，从而形成吐血。凡是见到眼睛闭合、目睛发红、神志昏迷、言语短促、眩晕昏冒、意识错乱、烦躁想含水漱口、狂躁惊悸、胡言乱语、鼻衄唾出红色血液、背部发冷、足部寒冷、四肢厥逆、胸腹部急迫胀满、大便黑色稀溏、小便频数，这些都是瘀血证的表現。这些症状不必全部具备，只要见到其中一两项，就应按血证进行治疗主张。刚得此病时，应紧急用药治疗。如果出血断断续续不止，经过数日后出现腹痛的，这就更难处理了。
经典著作指出：服用桂枝汤后出现呕吐的，其后必定会吐出脓血，适用犀角地黄汤。经过猛烈攻下治疗后，寸脉沉迟，尺脉摸不到，咽喉不利，吐出脓血的，适用麻黄升麻汤。这里有两个证候，一个是阳毒，一个是阴毒。阳毒使用升麻汤，阴毒使用甘桔汤加半夏、生姜。血热的，适用黄连阿胶汤、地榆柏皮汤、三黄泻心汤。
When heat in the meridians is excessive, forcing blood to flow recklessly and exit through the nose, it is called epistaxis (Nuxue). Although this is a heat syndrome, the pathogen remains in the meridians; however, diaphoresis (sweating method) should not be used. The classics state that using Guizhi Tang (Cinnamon Twig Decoction) or Mahuang Tang (Ephedra Decoction) to treat epistaxis does not directly treat the bleeding itself, but aims to dissipate the pathogenic qi within the meridians. Epistaxis often indicates that the disease is about to resolve. However, if epistaxis continues without stopping accompanied by sweating only on the head and no sweat on the body, along with fever, or if sweating fails to reach the feet, these are adverse signs (ominous syndromes) and must be clearly distinguished.
Epistaxis occurring in Taiyang syndrome (Taiyang Disease), or epistaxis induced after taking Guizhi Tang (Cinnamon Twig Decoction), indicates that the disease is about to resolve; Xijiao Dihuang Tang (Rhinoceros Horn and Rehmannia Decoction) is indicated. If epistaxis does not stop, Maohua Tang (Thistle Flower Decoction) is indicated. If there is no sweat but the patient can eat, indicating impending epistaxis, Huangqin Tang (Scutellaria Decoction) is indicated.
Patients with a history of frequent epistaxis (Nujia) should not undergo diaphoresis. If mistaken diaphoresis causes sweating, it will inevitably lead to depression of the forehead, urgent pulse, fixed gaze unable to move, and insomnia; Shaoyao Dihuang Tang (Peony and Rehmannia Decoction) is indicated.
In Yangming disease (Yangming Syndrome), thirst with a desire to rinse the mouth with water but not swallow it indicates impending epistaxis; Huangqin Shaoyao Tang (Scutellaria and Peony Decoction) is indicated.
Spontaneous diarrhea accompanied by epistaxis without prior purgation indicates Mahuang Shengma Tang (Ephedra and Asarum Decoction). A floating and large pulse, desire for fever, diarrhea, epistaxis, and dry heaving indicate Huangqin Shaoyao Tang (Scutellaria and Peony Decoction). Following epistaxis, irritability followed by thirst and drinking water that is immediately vomited: first administer Wuling San (Five-Ingredient Powder with Poria), then follow with Zhuye Shigao Tang (Bamboo Leaf and Gypsum Decoction).
In Shaoyin disease (Shaoyin Syndrome), presenting only with cold limbs and no sweat, forced diaphoresis will inevitably disturb the blood, causing it to flow from the mouth or nose, or from the eyes. This syndrome is named "Lower Jue and Upper Exhaustion" (Xia Jue Shang Jie) and is difficult to treat; Danggui Sini Tang (Angelica Sinensis and Cinnamon Twig Decoction) is indicated, combined with moxibustion on Taixi (KI3), Sanyinjiao (SP6), and Yongquan (KI1). Another method uses Heixi Dan (Black Tin Pill).
When the Yang meridians are affected by heat, and the pathogen is in the exterior, failure to induce sweat when indicated allows heat toxins to enter the zang organs, accumulating as stasis internally, thereby forming hematemesis (vomiting blood). Symptoms such as closed eyes with redness, coma, shortness of speech, dizziness and confusion, delirium, irritability with desire to rinse mouth with water, mania, palpitations, delirious speech, epistaxis with spitting of red blood, cold back and cold feet, cold limbs, acute fullness in the chest and abdomen, black loose stools, and frequent urination are all signs of blood stasis. These symptoms need not all be present; observing one or two is sufficient to diagnose and treat as a blood syndrome. Upon initial onset, urgent medication is required. If bleeding continues intermittently over several days followed by abdominal pain, the condition becomes difficult to manage.
The classics state: Vomiting after taking Guizhi Tang (Cinnamon Twig Decoction) leads to subsequent vomiting of pus and blood; Xijiao Dihuang Tang (Rhinoceros Horn and Rehmannia Decoction) is indicated. After severe purgation, if the cun pulse is deep and slow, the chi pulse is imperceptible, throat discomfort occurs, and pus and blood are spat out, Mahuang Shengma Tang (Ephedra and Asarum Decoction) is indicated. There are two syndromes here: Yang Du (Yang Toxin) and Yin Du (Yin Toxin). Yang Du is treated with Shengma Tang (Asarum Decoction), and Yin Du is treated with Ganjie Tang (Licorice and Platycodon Decoction) added with Banxia (Pinellia Tuber) and Shengjiang (Fresh Ginger). For blood heat, Huanglian Ejiao Tang (Coptis and Donkey-Hide Gelatin Decoction), Diyü Baipi Tang (Sanguisorba and Phellodendron Decoction), and Sanhuang Xiexin Tang (Three Yellows Heart-Purging Decoction) are indicated.
A floating pulse with fever, treated incorrectly with moxibustion, will inevitably cause dry throat and hematemesis; Jiuni Tang (Rescue Deviation Decoction) is indicated.
Throat obstruction contraindicates diaphoresis. Forced diaphoresis will cause hematemesis, vital qi nearing exhaustion, cold hands and feet, and curling up unable to self-warm; Danggui Sini Tang (Angelica Sinensis and Cinnamon Twig Decoction) is indicated.