疫疹之脉，未有不数者。有浮大而数者，有沉细而数者，有不浮不沉而数者，有按之若隐若见者。此《灵枢》所谓
阳毒伏匿之象也。诊其脉，即知其病之吉凶。浮大而数者，其毒发扬，一经凉散，病自霍然；沉细而数者，其毒已深，
大剂清解，犹可扑灭。至于若隐若见，或全伏者，其毒重矣，其证险矣！此脉得于初起者间有，得于七八日者颇多，何
也？医者，初认为寒，重用发表，先伤其阳。表而不散，继之以下，又伤其阴。殊不知伤寒五六日不解，法在当下，犹
必审其脉之有力者宜之。疫热乃无形之毒，病形虽似大热，而脉象细数无力，所谓壮火食气也。若以无形之火热，而当
硝、黄之猛烈，热毒焉有不乘虚而深入耶？怯弱之人，不为阳脱，即为阴脱。气血稍能驾驭者，亦必脉转沉伏，变证蜂
起。或四肢逆冷、或神昏谵语、或郁冒直视、或遗溺旁流，甚至舌卷囊缩，循衣摸床，种种恶候，颇类伤寒。医者不悟
引邪入内，阳极似阴，而曰变成阴证。妄投参、桂，死如服毒。遍身青紫，口鼻流血。如未服热药者，即用大剂清瘟，
败毒饮重加石膏，或可挽回。余因历救多人，故表而出之。
松浮洒于皮面，或红或赤，或紫或黑，此毒之外见者。虽有恶证，不足虑也。若紧束有根，如从皮里钻出，其色青
紫，宛如浮萍之背，多见于胸背，此胃热将烂之候。即宜大清胃热，兼凉其血。以清瘟败毒饮加紫草、红花、桃仁、归
尾。务使松活色淡，方可挽回。稍存疑虑，即不能救。
疫疹的脉象，没有不是数的。有的浮大而数，有的沉细而数，有的不浮不沉而数，有的按下去好像隐约可见。这是《灵枢》所说的阳毒潜伏隐匿的现象。诊察它的脉象，就能知道疾病的吉凶。脉象浮大而数的，说明邪毒正在发散，一经用清凉发散的方法治疗，病自然立刻痊愈；脉象沉细而数的，说明邪毒已经深入，用大剂量的清热解表药，还可以扑灭它。至于脉象若隐若现，或者完全伏匿的，说明邪毒很重，病情很危险！这种脉象在发病初期偶尔见到，在发病七八天时却很多见，为什么呢？医生起初误认为是寒证，重用发表药，先损伤了阳气。发表后病邪不散，接着又用泻下法，再次损伤了阴液。却不知道伤寒病到了五六天还没解除，治法应当在当下（使用下法），也一定要审察脉象有力的才适宜。疫热是无形的毒邪，病形虽然像大热证，但脉象细数无力，这就是所谓的“壮火食气”（亢盛的火热消耗人体正气）。如果用无形的火热之邪，去抵挡硝石、大黄这样猛烈的药物，热毒怎么会不趁着虚损而深入体内呢？体质虚弱的人，不是发生阳气外脱，就是发生阴液外脱。气血稍微能够驾驭药力的人，脉象也必然转为沉伏，变证蜂拥而起。有的四肢逆冷，有的神志昏迷胡言乱语，有的郁冒直视，有的遗尿或大便失禁，甚至舌头卷缩睾丸上缩，手循摸床沿，种种恶候，很像伤寒。医生不明白这是引邪入内，阳极似阴，反而说是变成了阴证。妄加人参、肉桂等热药，死亡就像服毒一样快。全身青紫，口鼻流血。如果没有服用热药的人，就用大剂量的清瘟败毒饮，重用石膏，或许可以挽回。我因为曾经救治过很多人，所以把这些情况列出来以示警。
疹色松浮洒于皮肤表面，或红或赤，或紫或黑，这是邪毒向外透发的表现。虽然有恶证，也不必担忧。如果疹子紧束有根，好像从皮里钻出来，颜色青紫，宛如浮萍的背面，多见于胸背部，这是胃热将要腐烂的征候。就应当大清胃热，兼以凉血。用清瘟败毒饮加入紫草、红花、桃仁、当归尾。务必使疹子变得松活、颜色变淡，才可以挽回。稍存疑虑，就不能救了。
The pulse of epidemic rash (Yizhen) is invariably rapid. It may be floating, large, and rapid; deep, fine, and rapid; neither floating nor deep but rapid; or it may feel faintly visible upon pressure. This corresponds to the phenomenon described in the *Ling Shu* (Spiritual Pivot) as "the manifestation of Yang toxin hiding and lying low." By examining the pulse, one can ascertain the prognosis of the disease. If the pulse is floating, large, and rapid, the toxin is emerging; a single treatment with cooling and dispersing methods will cause the illness to vanish instantly. If the pulse is deep, fine, and rapid, the toxin has penetrated deeply; however, it can still be extinguished with large doses of clearing and resolving agents. As for pulses that are faintly visible or completely hidden, the toxin is severe, and the condition is critical! Such pulses are occasionally seen at the onset, but frequently appear on the seventh or eighth day. Why? Physicians initially misdiagnose the condition as cold syndrome and heavily employ diaphoretic (sweat-inducing) methods, thereby first damaging Yang Qi. When sweating fails to disperse the pathogen, they subsequently resort to purgative methods, further damaging Yin fluids. They fail to realize that even if Cold Damage (Shanghan) persists beyond five or six days and warrants purgation, one must strictly verify that the pulse is forceful before proceeding. Epidemic heat is a formless toxin. Although the clinical presentation resembles intense heat, the pulse is fine, rapid, and weak—this is what is termed "vigorous fire consuming Qi" (Zhuang Huo Shi Qi). If one uses the fierce potency of Rhubarb (Dahuang) and Mirabilite (Xiaoshuang) against formless fiery heat, how can the heat-toxin not take advantage of the deficiency to penetrate deeper? In frail individuals, this leads either to Yang collapse or Yin collapse. Even in those whose Qi and Blood can somewhat manage the medication, the pulse inevitably turns deep and hidden, and complications arise like swarming insects. Symptoms may include cold extremities, coma with delirious speech, depression with fixed gaze, urinary incontinence or fecal leakage, and in extreme cases, tongue retraction and testicular retraction, hand groping along the bedrail, and various ominous signs resembling Cold Damage. Physicians fail to comprehend that this is inviting the pathogen inward, where extreme Yang mimics Yin, yet they mistakenly diagnose it as Yin syndrome. Prescribing hot herbs such as Ginseng (Renshen) and Cinnamon Twig (Guizhi) results in death as swift as taking poison. The body becomes blue-purple, and bleeding occurs from the mouth and nose. For those who have not taken hot medicines, administering a large dose of Qingwen Baidu Decoction (Plague-Resolving Toxin-Expelling Decoction) with a heavy addition of Gypsum (Shigao) might save them. Having saved many people through these methods, I record this for public awareness.
If the rash appears loose and scattered on the skin surface, varying in color from red to crimson, purple, or black, this indicates the toxin is manifesting outwardly. Even if accompanied by severe symptoms, there is little to worry about. However, if the rash is tight, rooted, appearing as if drilling out from beneath the skin, with a blue-purple color resembling the back of a duckweed, predominantly seen on the chest and back, this signals that stomach heat is causing tissue rot. Immediate treatment should focus on severely clearing stomach heat while simultaneously cooling the blood. Use Qingwen Baidu Decoction (Plague-Resolving Toxin-Expelling Decoction) supplemented with Arnebiae Radix seu Cortex (Zicao), Carthami Flos (Honghua), Persicae Semen (Taoren), and the tail end of Angelicae Sinensis Radix (Guiwei). It is essential that the rash becomes loose and pale in color to allow for recovery. Any hesitation renders the case incurable.