合病者。两阳经。或三阳经齐病。不传者也。并病者。一阳经先病未尽。又过一经。而
传者也。太阳阳明并病。若并未尽。所谓太阳症不罢。面赤佛郁。烦躁短气。是传未尽。尚有表
症。当麻黄桂枝各半汤汗之。若并已尽所谓太阳症罢。潮热。手足汗出。便硬。谵语。当承
气汤下之。三阳合病。皆自下利。太阳阳明合病。葛根汤。太阳少阳合病。黄芩汤。少阳阳
明合病。调胃承气汤。
阳厥者。初得病。身热头疼。以后传入三阴。大便闭。小便赤。谵渴躁乱。见诸热症而
发厥者。热极反兼胜已之化也。热微厥亦微。宜四逆散。热深厥亦深。宜承气汤。阴厥者。初得
病。无身热头疼。面寒肢冷。引衣蜷卧。见诸寒症而发厥者。轻则理中汤。重则四逆汤。二
厥之脉。皆沉。阴厥沉迟而弱。指头常冷。阳厥沉而滑。指头常温。
误投麻黄。汗多亡阳。误投承气。下多亡阴。老弱虚人。但当微利。或猪胆。或炼蜜导
之。尺脉弱者禁下。寸脉弱者禁吐。吐蛔一症。虽有热症。大忌寒凉。误服必死。初愈勿骤进参
。邪气得补即复。脉虚神倦者。不在禁例。宜随机活变。伤寒欲饮水为欲愈。不可禁绝。
不可多与。初愈勿过饱。勿劳动。勿忧怒。勿行房。勿食羊肉。勿多饮酒。勿轻见
风。
两感伤寒不须治。阴阳毒过七朝期。黑 下厥与上竭。阳症见阴脉者危。舌卷耳聋囊更
缩。阴阳交及摸寻衣。重 除中皆不治。唇吻青兮面黑黧。咳逆不已并脏结。溲屎遗失便难医。
汗出虽多不至足。口张目陷更何为。喘不休与阴阳易。离经脉见死当知。结胸症具烦躁甚。
直视摇头是死时。少阳症与阳明合。脉弦长大救时迟。汗后反加脉躁疾。须知脏厥死无疑。
合病，是指两条阳经，或者三条阳经同时发病，且没有传变的过程。并病，是指一条阳经的病邪尚未完全消除，又传入另一条经脉而发生的传变。
太阳病与阳明病并病，如果太阳病的病邪尚未完全解除，即所谓的“太阳证未罢”，表现为面部潮红、郁热不安、烦躁、呼吸短促，这说明病邪传变尚未结束，体表仍有症状，应当使用麻黄桂枝各半汤（由麻黄汤和桂枝汤各取三分之一剂量合方而成）进行发汗治疗。如果太阳病的病邪已经完全解除，即所谓的“太阳证已罢”，出现定时发热（潮热）、手足出汗、大便干硬、说胡话（谵语），则应当使用承气汤类方剂进行攻下治疗。
三阳合病，通常都会出现腹泻。其中，太阳病与阳明病合病，用葛根汤治疗；太阳病与少阳病合病，用黄芩汤治疗；少阳病与阳明病合病，用调胃承气汤治疗。
阳厥，是指刚得病时，身体发热、头痛，随后病邪传入三阴经，导致大便闭塞、小便赤黄、神志不清说胡话、口渴躁动，在出现各种热证的情况下发生四肢逆冷，这是热邪极盛反而兼有胜己之气的化生（即真热假寒）。热邪轻微则四肢逆冷也轻微，宜用四逆散治疗；热邪深重则四肢逆冷也深重，宜用承气汤治疗。
阴厥，是指刚得病时，没有身体发热和头痛，面色发凉、四肢冰冷，喜欢蜷缩身体裹着衣服躺卧，在出现各种寒证的情况下发生四肢逆冷，轻症用理中汤治疗，重症用四逆汤治疗。
这两种厥证的脉象都呈沉脉。阴厥的脉象沉迟而弱，手指头经常发冷；阳厥的脉象沉而滑，手指头温度正常。
误用麻黄汤，会导致出汗过多而亡失阳气；误用承气汤，会导致泻下过度而亡失阴液。对于年老体弱或气血亏虚的人，只应当轻微通便，或者使用猪胆汁，或者用炼蜜制成栓剂纳入肛门以导便。尺部脉象虚弱者禁止使用攻下法；寸部脉象虚弱者禁止使用催吐法。呕吐蛔虫这一症状，虽然伴有热证，但大忌使用寒凉药物，误服必然致死。初愈时不要立即进补人参，因为病邪得到补益就会复发。脉象虚弱、精神疲倦的人，不在此禁忌之列，应当根据具体情况灵活变通。伤寒病人想要喝水，是病情即将痊愈的迹象，不可以强行禁止饮水，但也不可以给予过多。初愈时不要吃得过饱，不要劳累，不要忧愁愤怒，不要行房事，不要吃羊肉，不要多喝酒，不要轻易吹风。
两感伤寒（表里两经同时受邪）不需要治疗（指预后极差，难以治愈）。阴阳毒病超过七天的期限（指病程迁延难愈）。黑斑（瘀斑）伴下肢厥冷和上部出血竭绝，阳证出现阴脉者危险。舌头卷曲、耳聋、睾丸收缩，阴阳交争以及患者无意识地摸寻衣被，重证除中（胃气败绝）都不治。嘴唇和嘴角发青，面色黑黄，咳嗽气逆不止以及脏结证，大小便失禁且排便困难者难医。出汗虽多但未到达足部，口张目陷者还有何救？喘促不停以及阴阳易病（大病初愈因房事复发的疾病），出现离经脉（脉象与季节或脏腑规律严重不符）者可知必死。结胸证具备且烦躁严重者，直视眼球固定不动、摇头者是在死亡之时。少阳病与阳明病合病，脉象弦大且长，此时救治为时已晚。发汗后脉象反而变得躁动疾速，须知这是脏厥，死亡无疑。
He Bing (Combined Disease) refers to the simultaneous onset of pathogenic factors in two Yang meridians, or three Yang meridians, without transmission. Bing Bing (Consecutive Disease) refers to the transmission where the pathogenic factor in one Yang meridian has not yet completely resolved, and then spreads to another meridian.
In the case of Taiyang and Yangming Bing Bing, if the Taiyang pathogenic factor has not yet completely resolved—manifesting as facial flushing,郁热 (stifling heat), irritability, and shortness of breath—it indicates that the transmission is incomplete and exterior symptoms remain. In this scenario, Mahuang Guizhi Gemi Tang (Mahuang and Guizhi Half-Volume Decoction) should be used to induce sweating. If the Taiyang pathogenic factor has completely resolved—manifesting as tidal fever, sweating on the hands and feet, hard stool, and delirium—the Taiyang syndrome has ceased. In this case, Chengqi Tang (Gut-Purging Decoction) should be used to purge the bowels.
San Yang He Bing (Combined Disease of the Three Yang Meridians) typically presents with diarrhea. Specifically, Taiyang and Yangming He Bing is treated with Gegen Tang (Kudzu Decoction); Taiyang and Shaoyang He Bing is treated with Huangqin Tang (Scutellaria Decoction); and Shaoyang and Yangming He Bing is treated with Tiaowei Chengqi Tang (Regulating the Stomach Gut-Purging Decoction).
Yang Jue (Yang Reversal/Cold Limbs due to Heat) occurs when a patient initially presents with fever and headache, after which the disease transmits to the Three Yin meridians. This leads to constipation, dark urine, delirium, thirst, and restlessness. The occurrence of cold limbs amidst these heat symptoms is described as "extreme heat manifesting as the transformation of the overcoming element" (True Heat, False Cold). Mild heat results in mild cold limbs, treated with Sini San (Frigid Extremities Powder); deep heat results in deep cold limbs, treated with Chengqi Tang.
Yin Jue (Yin Reversal/Cold Limbs due to Cold) occurs when a patient initially lacks fever and headache, presenting instead with a cold face, cold limbs, a preference for curling up and covering oneself, and cold limbs amidst cold symptoms. Mild cases are treated with Lizhong Tang (Regulate the Middle Decoction); severe cases are treated with Sini Tang (Frigid Extremities Decoction).
The pulse in both types of Jue is Chen (Deep). In Yin Jue, the pulse is Deep, Slow, and Weak, with cold fingertips; in Yang Jue, the pulse is Deep and Slippery, with warm fingertips.
Misuse of Mahuang Tang can lead to excessive sweating and loss of Yang Qi. Misuse of Chengqi Tang can lead to excessive purging and loss of Yin fluids. For elderly, weak, or deficient individuals, only mild laxation should be induced, using either pig bile or refined honey as an enema/suppository. A weak Chi (Cun-Che-Guan: Chi position) pulse contraindicates purging; a weak Cun (Cun-Che-Guan: Cun position) pulse contraindicates emesis. Vomiting roundworms, despite accompanying heat symptoms, strictly forbids the use of cold-natured herbs; misuse will result in death. After initial recovery, do not abruptly administer Ginseng (Renshen), as tonification may cause the residual pathogen to rebound. However, patients with a Deficient pulse and mental fatigue are exempt from this prohibition and require flexible treatment. Thirst in a Shanghan (Cold Damage) patient indicates impending recovery; water intake should not be strictly forbidden but also not given in excess. After recovery, avoid overeating, physical exertion, emotional agitation (worry/anger), sexual intercourse, eating mutton, excessive alcohol consumption, and exposure to wind.
Liang Gan Shanghan (Simultaneous Contraction of Exterior and Interior in Cold Damage) is considered untreatable (due to poor prognosis). Yang-Yin Du (Yin-Yin Toxicity) persisting beyond seven days is difficult to manage. Black spots (ecchymosis) with lower limb reversal and upper body bleeding exhaustion, Yang syndromes presenting with Yin pulses, tongue retraction, deafness, testicular retraction, Yin-Yang Jiao (Intertwining of Yin and Yang), involuntary grasping at bedclothes, severe Chu Zhong (Stomach Qi Exhaustion), cyanotic lips and corners of the mouth, sallow black complexion, persistent cough and counterflow qi, Zang Jie (Zang Knotting), incontinence of urine and feces with difficult defecation, sweating that does not reach the feet, open mouth and sunken eyes, unceasing panting, Yin-Yang Yi (Transmission between Yin and Yang via sexual contact), Li Jing Mai (Departing Pulse), full presentation of Jie Xiong (Chest Binding) with severe irritability, fixed staring, and head shaking—all indicate imminent death. When Shaoyang and Yangming combine, a String-taut, Large, and Long pulse indicates it is too late to save. Sweating followed by a rapid and restless pulse indicates Zang Jue (Visceral Reversal), which is undoubtedly fatal.