夫痘之际，头面宜凉，手足宜温，反此则为逆矣。至于厥则更甚于逆而乃冷也。逆
则阳气衰，厥则阴气胜，头乃诸阳气之会，痘毒之气上蒸，故温也。足冷者，是阴阳之
气下绝也，不治。盖四肢属脾，而脾又统周身，为诸阳之本。如指头微寒，则阳气衰，
夫阳气起于十指之端也。若足心冷则阴气胜，阴脉集于足下而趋于足心也。然焦黑烦
渴顿闷喘促而厥逆者，此热深厥亦深，火极似水，乃阳毒内陷也。若灰白顶陷，吐泻兼
并而厥逆者，此元气虚惫，阴阳不接也，总皆恶候。若手足冷而曾多吐泻者，此脾脏虚
怯也。四肢皆禀气于胃，脾胃气弱，不得至于经耳。若在痘未出时，则于发表之内，当
兼和中，不可单行发表以致复虚胃气，至若阳气虚寒而饮沸不热者，则急投参附重复，
盖覆使阴返阳回而自顺矣。如阳气大脱足冷过膝者，不治。
痘中厥冷者，多因毒瓦斯郁遏于内，而元气不得行诸中外，是以致表无阳也，宜理中
汤加减服之。然有阴阳二症，凡二便俱秘，烦躁狂妄，腹胀喘渴者为阳厥，宜疏利以宜
发阳气。如呕吐自利，阳气欲脱者，为阴厥，治宜温补，以追复元阳。大抵暴得非
阴，久病非阳，盖胃伤则生风呕吐，脾伤则生风厥逆，多属脾宫无阳而四肢无以禀受也。
在痘疹发病期间，头面部应当保持清凉，手足应当保持温暖，如果与此相反，就称为“逆”。至于出现“厥”的症状，则比“逆”更为严重，表现为寒冷。“逆”是因为阳气衰微，“厥”则是阴气亢盛。头部是诸阳经汇聚之处，痘毒之气向上蒸腾，所以头部应该是温暖的。如果足部发冷，说明阴阳之气在下部断绝，属于不治之症。四肢归属于脾脏，而脾脏统摄全身，是诸阳气的根本。如果手指尖微微发凉，说明阳气衰微，因为阳气起始于十个指尖的末端。如果脚心发冷，说明阴气亢盛，因为阴脉聚集在脚下并趋向于脚心。然而，如果出现焦黑、烦躁口渴、突然胸闷、气喘急促并且伴有厥逆的情况，这是热邪深重导致厥逆也深重，火极似水，属于阳毒内陷。如果出现颜色灰白、痘顶凹陷，同时伴有呕吐腹泻和厥逆的情况，这是元气虚弱疲惫，阴阳之气不相接续，这些都属于恶候。如果手足冰冷且曾经有多次呕吐腹泻的情况，这是脾脏虚怯所致。四肢的气血都禀受于胃，脾胃之气虚弱，气血就不能到达经络。如果在痘疹尚未发出时，应当在发表（发散表邪）的药物中，兼顾调和脾胃，不可单纯使用发表药物而导致胃气再次受损。如果是阳气虚寒，饮水沸腾后仍不热，则应立即投予人参、附子等重复服用，加盖衣被使阴气返还、阳气回复，从而自然顺遂。如果阳气大脱，足冷超过膝盖，则属不治。
痘疹中出现厥冷的情况，多是因为毒瓦斯郁结阻滞在体内，导致元气不能运行于身体内外，致使体表缺乏阳气，适宜加减服用理中汤。然而，这里有阴证和阳证两种情况。凡是大小便都闭塞不通，烦躁狂妄，腹胀气喘口渴的，属于阳厥，适宜用疏利的方法以宣发阳气。如果是呕吐且自发性腹泻，阳气将要脱失的，属于阴厥，治疗适宜温补，以追回恢复元阳。大体上来说，突然得病的多非阴证，久病的多非阳证。这是因为胃受伤则生风呕吐，脾受伤则生风厥逆，大多属于脾宫没有阳气，四肢无法禀受阳气所致。
During the course of smallpox (or variola), the head and face should be cool, while the hands and feet should be warm; if this is reversed, it is termed "Ni" (Reversal). The condition of "Jue" (Cold Extremities) is even more severe than "Ni," manifesting as coldness. "Ni" indicates a decline in Yang Qi (Vital Energy), whereas "Jue" signifies an excess of Yin Qi (Cold/Dark Energy). The head is the convergence point of all Yang meridians; due to the upward steaming of the toxin from the pox, the head should remain warm. Coldness in the feet indicates that the Qi of Yin and Yang has severed at the lower body, which is considered incurable. The four limbs belong to the Spleen, which governs the entire body and serves as the root of all Yang Qi. If the fingertips are slightly cold, it indicates a decline in Yang Qi, as Yang Qi originates from the ends of the ten fingers. If the soles of the feet are cold, it indicates an excess of Yin Qi, as the Yin meridians gather at the soles and tend toward the center of the foot. However, if one presents with blackened lesions, irritability, thirst, sudden chest oppression, panting, and Jue Ni (Reversal Cold), this represents deep heat leading to deep Jue, where extreme fire resembles water, indicating the internal collapse of Yang Toxin. If the lesions are grayish-white with depressed crowns, accompanied by vomiting, diarrhea, and Jue Ni, this indicates exhaustion of Yuan Qi (Primal Qi) and a lack of connection between Yin and Yang; these are all ominous signs. If the hands and feet are cold and there has been frequent vomiting and diarrhea, this is due to deficiency and weakness of the Spleen organ. The four limbs derive their Qi from the Stomach; when the Qi of the Spleen and Stomach is weak, it cannot reach the meridians. If this occurs before the eruption of the pox, one should combine harmonizing the middle jiao (digestive system) with releasing the exterior (dispelling external pathogens); one must not solely use exterior-releasing methods, which would further deplete Stomach Qi. In cases of Yang Qi deficiency and cold, where even boiling water fails to stay hot, one should urgently administer Ginseng Radix et Rhizoma (Renshen) and Aconiti Lateralis Radix Praeparata (Fuzi) repeatedly, covering the patient to restore Yin and return Yang, thereby achieving natural harmony. If Yang Qi is severely depleted and coldness extends above the knees, it is incurable.
Jue Leng (Cold Extremities) in pox diseases is mostly caused by toxic vapors stagnating internally, preventing Yuan Qi from circulating within and outside the body, resulting in a lack of Yang at the surface. It is appropriate to administer modified Lizhong Tang (Regulate the Middle Decoction). However, there are two patterns: Yin and Yang. When both urination and defecation are obstructed, accompanied by irritability, delirium, abdominal distension, panting, and thirst, it is classified as Yang Jue (Yang Reversal); it is suitable to use draining and promoting methods to diffuse Yang Qi. If there is vomiting and spontaneous diarrhea, indicating impending collapse of Yang Qi, it is classified as Yin Jue (Yin Reversal); treatment should focus on warming and tonifying to recover Yuan Yang. Generally, acute onset is rarely Yin pattern, while chronic illness is rarely Yang pattern. This is because damage to the Stomach generates Wind leading to vomiting, and damage to the Spleen generates Wind leading to Jue Ni; these mostly belong to a lack of Yang in the Spleen palace, leaving the four limbs without Qi reception.