阳明衄血，热在里也。太阳衄血，热瘀经也。太阳失汗，则有头痛目瞑之兆，阳明失下，则有漱水不欲
咽之征。衄血之后，身凉脉静，知作解也。若仍不解，知衄未尽，热留于营分也。无汗表热者，宜葛根合犀
角地黄汤清解之。欲作衄未衄，表实者，宜麻黄汤汗之，里热者宜犀角地黄汤加芩连清之。若表实里热者，
则又当合二方两解之。
伤寒吐血，皆因失汗失下，火逆以致邪热炽盛，沸腾经血故也。若血从口鼻耳目而出，小便难，此为强发
少阴汗，名曰下厥上竭，为难治。如三阳热盛，吐血者，宜葛根合犀角地黄汤，热甚加芩连清解。若血瘀则胸
满或痛，当以桃仁承气合犀角地黄汤攻之。若暴吐腐臭之血，名曰内溃，内溃者死。若吐血过多，面唇无红色
，名曰血脱无救，脱轻者宜圣愈汤，重者宜人参养荣汤。
阳经之热，下注膀胱，伤其营分，热少血多，瘀成血蓄；热多血少，热迫血行，血不得蓄，而走下窍，
故尿血也，以导赤散利而清之。阴经之热，转迫阳明，伤其营分，瘀则血蓄，喜忘如狂。不蓄则便血，热腐则
便脓，便脓热郁，里急下重所必然也。轻者宜黄连阿胶汤，重者宜白头翁汤，滑脱者宜桃花汤涩之。
伤寒颐毒，皆因汗下失宜，毒热挟少阳相火上攻而成此证也。若其人阳气素盛，则高肿 红疼痛，易于
成脓，故为顺也。宜连翘败毒散散之。或其人阳气素虚，或服冷药过多，遏郁毒热，伏藏在里，内攻神昏，
外毒漫肿，肉色不变，不疼木硬，则命必危也。毒伏未发之前，往往似三阴亡阳之证，脉隐不见，冷汗淋漓
，肢冷如冰，但身轻目睛了了，烦渴，不大便，指甲红紫为异，此毒发始，临治不可忽也。
阳明经的鼻衄，是热邪在里的表现。太阳经的鼻衄，是热邪郁滞于经脉所致。太阳病若未能及时发汗，就会出现头痛、眼睛昏花等症状；阳明病若未能及时攻下，就会出现想含水漱口但不想咽下的征象。鼻衄之后，如果身体凉爽、脉搏平静，说明病情即将解除。如果仍然没有缓解，说明衄血不彻底，热邪仍留存在营分。对于无汗且体表发热者，适宜用葛根汤合犀角地黄汤来清热解表。对于想要衄血但尚未衄出、表实证者，适宜用麻黄汤发汗；里热盛者，适宜用犀角地黄汤加黄芩、黄连来清热。如果既表实又里热，则应当将两方合用，表里双解。
伤寒导致的吐血，都是因为失于发汗或失于攻下，导致火气逆乱，邪热炽盛，沸腾经脉中的血液所致。如果血液从口、鼻、耳、目流出，小便困难，这是因为强行发少阴经之汗，称为“下厥上竭”，属于难治之证。如果是三阳经热盛导致的吐血，适宜用葛根汤合犀角地黄汤，热势极重时加黄芩、黄连清热。如果伴有血瘀，出现胸部胀满或疼痛，应当用桃仁承气汤合犀角地黄汤攻逐瘀血。如果突然吐出腐败臭秽的血液，称为“内溃”，内溃者预后不良，多致死。如果吐血过多，面色和嘴唇失去红润色泽，称为“血脱”，难以救治；血脱较轻者适宜用圣愈汤，较重者适宜用人参养荣汤。
阳经的热邪，向下注于膀胱，损伤营分。若热少血多，瘀积而成蓄血证；若热多血少，热迫血行，血液无法瘀积，而向下窍流出，故形成尿血，适宜用导赤散利尿清热。阴经的热邪，转而逼迫阳明，损伤营分。若形成瘀积，则表现为善忘、如狂状；若不形成瘀积，则出现便血；若热邪腐肉，则出现便脓。便脓因热郁所致，必然伴随里急后重。轻症适宜用黄连阿胶汤，重症适宜用白头翁汤，滑脱不禁者适宜用桃花汤固涩。
伤寒引起的颐部毒肿（颐毒），都是因为发汗或攻下不当，导致毒热挟带少阳相火上攻而形成此证。如果患者素来阳气旺盛，则局部高肿、发红、疼痛，容易成脓，这属于顺证。适宜用连翘败毒散消散毒邪。如果患者素来阳气虚弱，或者服用寒凉药物过多，导致毒热被遏制郁结，潜伏在体内，内攻导致神志昏迷，外现毒肿漫延、肤色不变、不痛且麻木坚硬，则性命危殆。在毒邪潜伏未发作之前，往往类似三阴经亡阳的证候，脉象隐伏不见，冷汗淋漓，四肢冰冷如冰，但身体轻盈、眼神清明、烦躁口渴、大便不通，指甲呈红紫色为异常特征，这是毒邪开始发作的表现，临证治疗不可轻视。
Nasal bleeding (epistaxis) from the Yangming channel indicates heat in the interior. Nasal bleeding from the Taiyang channel indicates heat stagnation in the meridians. Failure to induce sweating in Taiyang disease leads to symptoms such as headache and blurred vision; failure to purge in Yangming disease leads to signs such as rinsing the mouth with water but not swallowing it. After nasal bleeding, if the body becomes cool and the pulse is calm, it indicates that the disease is resolving. If it does not resolve, it indicates incomplete bleeding and heat remaining in the Ying (Nutritive) level. For cases with no sweat and exterior heat, Gegen Tang (Kudzu Decoction) combined with Xijiao Dihuang Tang (Rhino Horn and Rehmannia Decoction) should be used to clear and resolve. For cases where bleeding is about to occur but has not yet, with excess exterior syndrome, Mahuang Tang (Ephedra Decoction) should be used to induce sweating; for interior heat, Xijiao Dihuang Tang combined with Huangqin (Scutellariae Radix) and Huanglian (Coptidis Rhizoma) should be used to clear heat. If there is both exterior excess and interior heat, the two formulas should be combined to resolve both exterior and interior simultaneously.
Hematemesis (vomiting blood) caused by Cold Damage (Shanghan) results from failure to sweat or purge, leading to rebellious fire and excessive pathogenic heat that boils the blood in the meridians. If blood flows from the mouth, nose, ears, or eyes, accompanied by difficult urination, this is due to forcibly inducing sweat from the Shaoyin channel, known as "Jue at the Lower and Exhaustion at the Upper," which is difficult to treat. If hematemesis is caused by excessive heat in the Three Yang channels, Gegen Tang combined with Xijiao Dihuang Tang should be used; if heat is severe, add Huangqin and Huanglian to clear heat. If blood stasis is present, causing chest fullness or pain, Tao Ren Chengqi Tang (Peach Kernel and Rheum Decoction) combined with Xijiao Dihuang Tang should be used to attack the stasis. If foul-smelling, putrid blood is suddenly vomited, it is called "internal ulceration," which is fatal. If too much blood is lost, resulting in a lack of red color on the face and lips, it is called "blood exhaustion" and is incurable; for mild cases, Shengyu Tang (Sage Renewal Decoction) is suitable, and for severe cases, Renshen Yangrong Tang (Ginseng and Nourishing Qi and Blood Decoction) is suitable.
Heat from the Yang channels flowing downward into the Bladder damages the Ying level. If heat is slight and blood is abundant, blood stasis accumulates (Blood Accumulation); if heat is abundant and blood is slight, heat forces blood to move, preventing accumulation, so it flows out through the lower orifices, causing Hematuria (blood in urine), which should be treated with Daochi San (Guide Out Red Powder) to promote diuresis and clear heat. Heat from the Yin channels turning to force the Yangming channel damages the Ying level. If stasis forms, it causes forgetfulness and mania-like states; if no stasis forms, it causes Hematochezia (blood in stool); if heat rots flesh, it causes Pus in Stool. Pus in stool due to heat stagnation inevitably leads to Tenesmus (urgent need to defecate with little result). Mild cases are treated with Huanglian Ejiao Tang (Coptis and Donkey-Hide Gelatin Decoction), severe cases with Baitouweng Tang (Pulsatilla Decoction), and cases with slipping/incontinence with Taohua Tang (Peach Flower Decoction) to astringe.
Yi Du (Toxic Swelling of the Jaw/Parotid region) in Cold Damage results from improper sweating or purging, causing toxic heat to carry Shaoyang Ministerial Fire upward. If the person's Yang qi is naturally robust, the swelling will be high, red, and painful, easily forming pus, which is a favorable sign (Shun). Liaoqiao Baidu San (Forsythia and Detoxifying Powder) should be used to dissipate it. If the person's Yang qi is naturally deficient, or if too many cold medicines were taken, suppressing and stagnating the toxic heat, causing it to hide in the interior and attack internally leading to coma, while externally showing spreading toxic swelling with unchanged skin color, numbness, hardness, and no pain, life is endangered. Before the toxin manifests, it often resembles the syndrome of Yang collapse in the Three Yin channels: pulse is hidden/unfelt, cold sweat pours down, limbs are cold as ice, but the body feels light, eyes are clear, there is irritability and thirst, constipation, and purple-red fingernails are abnormal features. This marks the onset of toxin eruption; clinical treatment must not neglect it.