凡阳厥，手足厥冷，或冷过肘膝，甚至手足指甲皆青黑，剧则遍身冰冷如石，血
凝青紫成片，或六脉无力，或脉微欲绝，以上脉证，悉见纯阴，犹以为阳证何也？及审内证
，气喷如火、龈烂口臭、烦渴谵语、口燥舌干、舌苔黄黑或生芒刺、心腹痞满、小腹疼痛、
小便赤色、涓滴作痛，非大便燥结，即大肠胶闭，非协热下利，即热结旁流，以上内三焦悉见阳证
，所以为阳厥也。粗工不察，内多下证，但见表证，脉体纯阴，误投温剂，祸不旋踵
凡阳证似阴者，温疫与正伤寒通有之；其有阴证似阳者，此系正伤寒家事，在温疫无有此证
，故不附载。（详见《伤寒实录》）
温疫阳证似阴者，始必由膜原，以渐传里，先几日发热，以后四逆；伤寒阳证似阴者，
始必由阳经发热，脉浮而数，邪气自外渐次传里，里气壅闭，脉体方沉，乃至四肢厥逆，盖
非一日矣。其真阴者，始则恶寒而不发热，其脉沉细，当即四逆，急投附子回阳，二、
三日失治即死。
捷要辨法，凡阳证似阴，外寒而内必热，故小便血赤；凡阴证似阳者，格阳之证也，上热下
寒，故小便清白，但以小便赤白为据，以此推之，万不失一。
尝遇微疫，医者误进白虎汤数剂，续得四肢厥逆，脉势转剧，更医谬指为阴证，
投附
子汤病愈。此非治病，实治药也，虽误认病原，药则偶中。医者之庸，病者之福也。盖病本不
药自愈之证，因连进白虎寒凉 悍，抑遏胃气，以
致四肢厥逆，疫邪强伏，故病增剧，今投
温剂，胃气通行，微邪流散故愈。若果直中，无阳阴证，误投白虎一剂立毙，岂容数剂耶？
凡是阳厥，表现为手足冰冷，有的冷过肘部和膝盖，甚至手足指甲都变成青黑色，病情严重时全身冰冷像石头一样，血液凝结呈青紫色成片状，或者六脉无力，或者脉搏微弱几乎摸不到，以上这些脉象和症状，看起来全是纯阴证的表现，为什么还认为是阳证呢？等到仔细审查内部的症状，气息喷出像火一样烫，牙龈腐烂口臭，烦躁口渴说胡话，口腔干燥舌头干裂，舌苔黄黑或者长出芒刺，心腹部痞塞胀满，小腹疼痛，小便颜色深红，点滴排出时伴有疼痛，不是大便燥结，就是大肠胶闭不通，不是协热下利，就是热结旁流，以上内三焦全部显现出阳证的表现，所以称为阳厥。粗疏的医生不加以考察，体内虽然有可下的实证，但只看到表面的寒象，脉象完全是阴脉，误用温补药物，灾祸立刻降临。
凡是阳证表现出类似阴证的情况，温疫和正伤寒都有这种情况；那些有阴证表现出类似阳证的情况，这是正伤寒特有的事情，在温疫中没有这种证候，所以不附带记载。（详见《伤寒实录》）
温疫中阳证似阴的情况，开始必然由膜原（半表半里的部位）逐渐传入体内，先发热几天，然后出现四肢逆冷；伤寒中阳证似阴的情况，开始必然由阳经发热，脉象浮而快，邪气从外部逐渐传入体内，体内气机壅塞闭塞，脉象才变得沉，以至于四肢逆冷，这已经过了一天以上的过程了。那些真正的阴证，开始时怕冷而不发热，脉象沉细，应当立即使用四逆汤，如果急投附子回阳救逆，两三天治疗延误就会死亡。
简便重要的辨别方法，凡是阳证似阴，外表寒冷但内部一定热，所以小便深红；凡是阴证似阳的情况，是格阳证，上面热下面寒，所以小便清亮白色，只要以小便红白作为依据，以此推断，万无一失。
我曾经遇到轻微的瘟疫，医生误用了白虎汤几剂，接着出现四肢逆冷，脉势更加严重，换医生错误地指认为阴证，投用附子汤后病好了。这并非治病，实际上是治药造成的副作用，虽然错误认识了病原，但药物偶然对症。医生的庸碌，却是病人的福气。因为疾病本来是不用药也能自愈的证候，因为连续服用白虎汤的寒凉猛烈之性，抑制遏制了胃气，导致四肢逆冷，疫邪强力潜伏，所以病情加重，现在投用温补药物，胃气通行，微弱的邪气流散所以痊愈。如果是真正的直中阴经，没有阳气的阴证，误用一剂白虎汤就会立即死亡，哪里容许用几剂呢？
In cases of Yang Jue (Yang collapse with cold extremities), the hands and feet are cold; in some cases, the cold extends beyond the elbows and knees, or even the fingernails and toenails turn cyanotic and black. In severe cases, the entire body becomes ice-cold like stone, blood coagulates into patches of cyanosis, or the six pulses are powerless, or the pulse is faint and nearly imperceptible. The above pulse and symptom manifestations all appear as pure Yin syndrome, yet why is it still considered a Yang syndrome? Upon careful examination of internal symptoms, breath sprays out like fire, gums rot and there is foul odor, restlessness, thirst, and delirious speech, dry mouth and tongue, yellow or black tongue coating or prickles on the tongue, epigastric and abdominal fullness and obstruction, lower abdominal pain, dark red urine that passes drop by drop with pain. This is either dry fecal impaction or sticky closure of the large intestine, or diarrhea with heat binding, or heat accumulation with purgation of clear fluid. All three internal jiaos manifest Yang syndrome characteristics, hence it is called Yang Jue. Unskilled physicians fail to investigate thoroughly; although there are internal excess syndromes requiring purgation, they only see the external cold signs and purely Yin pulse qualities, mistakenly administering warming agents, bringing disaster swiftly.
Cases where Yang syndrome resembles Yin occur in both warm epidemics and true cold damage; however, cases where Yin syndrome resembles Yang belong exclusively to the domain of true cold damage and do not occur in warm epidemics, thus they are not included here (see *Shanghan Shilu* for details).
In warm epidemics, when Yang syndrome resembles Yin, it begins at the Mo Yuan (membrane source) and gradually transmits inward. It first presents with fever for several days, followed by cold extremities (Si Ni). In true cold damage, when Yang syndrome resembles Yin, it initially presents with fever from the Yang meridians, with a floating and rapid pulse. Pathogenic factors transmit inward gradually from the exterior; internal Qi becomes congested and blocked, causing the pulse to become deep, leading to cold extremities, which takes more than one day to develop. In true Yin syndrome, it begins with aversion to cold without fever, with a deep and fine pulse, immediately requiring Si Ni Tang (Four Reversals Decoction); if Aconite is urgently administered to restore Yang, and treatment is delayed for two or three days, death ensues.
A concise method for differentiation: In Yang syndrome resembling Yin, the exterior is cold but the interior is necessarily hot, so urine is dark red. In Yin syndrome resembling Yang, this is Ge Yang syndrome (floating Yang), characterized by upper heat and lower cold, so urine is clear and white. Relying solely on whether urine is red or white ensures absolute accuracy in diagnosis.
I once encountered a mild epidemic case where a physician mistakenly administered Bai Hu Tang (White Tiger Decoction) for several doses, subsequently developing cold extremities and worsening pulse condition. Another physician erroneously diagnosed it as a Yin syndrome and prescribed Fu Zi Tang (Aconite Decoction), resulting in recovery. This was not treating the disease but treating the iatrogenic effects of medication; although the pathogen was misidentified, the remedy happened to be correct by chance. The physician's incompetence became the patient's fortune. The illness was originally self-limiting and would have resolved without medication. However, continuous administration of the harsh, cold-natured Bai Hu Tang suppressed Stomach Qi, causing cold extremities and forcing the epidemic pathogen to lie dormant, thereby aggravating the condition. The subsequent use of warming agents allowed Stomach Qi to circulate freely, dispersing the residual pathogens, leading to recovery. If it were a direct attack on the Yin channels without any Yang presence, a single dose of Bai Hu Tang would cause immediate death; how could multiple doses be tolerated?