火动则热，火郁则寒。盖毒欲发泄而不得散耳，将出而有气血与火毒相攻也。出之而有者，毒盛则邪
胜也，宜用柴胡、知母、石膏、地骨，便闭加大黄可也。
热如炮烙者有之，头温足冷者有之，唇焦颊赤者有之，青惨黯滞者有之，周身发热参半者有之，阴阳殊绝
者有之。其所以然，毒火有隐现之分，非真有寒热之界也。热者有微热，有半热，有极热之不同者，宜知之。
厥者，手足逆冷人事不知也。阳气独上，火随痰涌气塞不行而厥也。热毒之气郁遏于内，元气不得流通，
以致外表无阳而厥冷也。宜发散之中加麻、桂、葱头，阴虚火旺则内热生风，火气焚灼，故身热肢冷，痰随火
涌，故不知人事。又有血厥者，汗出过多，血少则阳气独上，气塞不通之故耳。
头乃诸阳之会，毒瓦斯上蒸故温，足之六经属水土木，水寒则冰，土寒则拆，木寒则枯，足冷者，阳气绝
也。《经》云∶足冷过膝者不治。但疹出郁于上而足冷者，宜清之于上，则火降而足温。四肢脾胃主之，
是以四肢先见者不治，疹后四肢冰冷亦不治也。
疹后头汗如淋，毒惨阳位者则不治。若治，宜前开录四十九日后之方治之，此因火性炎上，兼之渗泄
无门，不容滂达，焰光上窜，汗之所以上涌若蒸也。四肢属脾宜和暖之故，不宜热，尤
不宜冷，通身火热而手足独冷者，皆烈毒涌遏于脾阳，邪莫透，
火郁则寒之象，冷之极，正热之极也。未出之时，则用麻桂以散之，而火自收矣。
火气亢盛则表现为热，火气郁结阻滞则表现为寒。这是因为痘毒想要向外发泄却无法散开，在痘疹将要发出时，气血与火毒相互搏结所致。痘疹发出后出现症状的，是因为毒邪炽盛导致邪气占上风，适宜使用柴胡、知母、石膏、地骨皮；若伴有便秘，可以加大黄。
有的患者热势如同被烙铁灼烧，有的患者头部温热而足部寒冷，有的患者嘴唇焦裂、脸颊红赤，有的患者面色青紫惨暗、晦滞不通，有的患者周身发热但程度不一，有的患者阴阳之气隔绝断绝。之所以如此，是因为毒火有隐伏和显露的区别，并非真正存在寒证与热证的绝对界限。发热的情况有轻微发热、半发热、极热等不同表现，应当知晓。
厥证，是指手足逆冷且人事不知。这是由于阳气单独上越，火气随着痰浊上涌，气机闭塞不通而导致厥逆。热毒之气郁结阻滞于体内，元气不能流通，导致体表缺乏阳气而出现四肢厥冷。治疗应在发散药中加入麻黄、桂枝、葱白；若是阴虚火旺，则内生风热，火气焚烧灼伤，所以身体发热而四肢冰冷，痰随火势上涌，因此人事不知。又有血厥的情况，是由于出汗过多，血液亏少导致阳气单独上越，气机闭塞不通的缘故。
头部是诸阳经汇聚之处，毒气上蒸所以头部温热；足部的六经分别属水、土、木，水寒则结冰，土寒则崩裂，木寒则枯死，足部寒冷，意味着阳气衰竭。《内经》说：足冷超过膝盖的属于不治之症。但是如果是痘疹郁结于上部而导致足冷的，适宜在上部进行清解，那么火气下降而足部回暖。四肢由脾胃所主，所以四肢先出现异常（如冰冷）的属于不治，痘疹消退后四肢依然冰冷的也不治。
痘疹消退后头部出汗如雨，毒气严重侵犯阳位（头部）的属于不治。如果进行治疗，适宜参考前面记载的四十九天后的方剂来治疗，这是因为火性炎上，加上津液渗泄无路，不容许大量排泄，火焰光芒向上窜动，汗液因此向上涌出如同蒸腾一样。四肢属于脾，适宜温和温暖，不宜过热，尤其不宜过冷。全身火热而唯独手足冰冷的，都是烈毒涌遏于脾阳，邪气无法透发，这是火气郁结导致寒冷的现象，寒冷到了极点，正是热极的表现。在痘疹未发出之时，则使用麻黄、桂枝来发散，火气自然收敛。
When Fire is active, it manifests as heat; when Fire is depressed and stagnant, it manifests as cold. This is because the toxin desires to vent but cannot disperse; when erupting, Qi and Blood attack the Fire-Toxin together. If symptoms appear after eruption, it indicates that the toxin is abundant and the pathogenic factor prevails. It is appropriate to use Chai Hu (Bupleuri Radix), Zhi Mu (Anemarrhenae Rhizoma), Shi Gao (Gypsum Fibrosum), and Di Gu Pi (Cortices Lycii). If constipation is present, Da Huang (Rhei Radix et Rhizoma) can be added.
There are cases where the heat is intense like being branded by a hot iron, cases where the head is warm but the feet are cold, cases where the lips are scorched and cheeks are red, cases where the complexion is cyanotic, miserable, dark, and sluggish, cases where the whole body has fever with varying degrees, and cases where Yin and Yang are completely severed. The reason for this is that the Fire-Toxin has distinctions between being hidden and manifest; there is no true absolute boundary between Cold and Heat syndromes. One should know that heat conditions vary from slight heat, half-heat, to extreme heat.
Jue syndrome refers to coldness of the hands and feet extending upwards, accompanied by loss of consciousness. This occurs when Yang Qi rises alone, and Fire surges upward with Phlegm, causing Qi obstruction and stagnation, leading to Jue. When the Qi of Heat-Toxin is depressed and blocked internally, Yuan Qi cannot circulate freely, resulting in a lack of Yang on the exterior and thus cold extremities. Treatment should involve dispersing agents supplemented with Ma Huang (Ephedrae Herba), Gui Zhi (Ramulus Cinnamomi), and Cong Bai (Sclerium Allii Cepae). If Yin deficiency leads to hyperactive Fire, internal heat generates Wind, and Fire burns and scalds, causing body heat with cold limbs; Phlegm surges with Fire, leading to unconsciousness. There is also Blood Jue, caused by excessive sweating leading to blood depletion, which causes Yang Qi to rise alone and Qi obstruction.
The head is the convergence point of all Yang meridians; toxins vaporize upward, making it warm. The six meridians of the feet belong to Water, Earth, and Wood elements: Water becomes ice when cold, Earth cracks when cold, and Wood withers when cold. Cold feet indicate the exhaustion of Yang Qi. The Classic states: "Cold feet extending above the knees are untreatable." However, if foot coldness is due to rash toxins depressing in the upper part, clearing the upper part is appropriate, so that Fire descends and feet become warm. The four limbs are governed by the Spleen and Stomach; therefore, abnormalities appearing first in the limbs are untreatable, and cold limbs persisting after the rash subsides are also untreatable.
If head sweat pours like rain after the rash, and toxins severely invade the Yang position (head), it is untreatable. If treatment is attempted, one should refer to the prescriptions recorded for the forty-ninth day mentioned earlier. This is because Fire nature flares upward, combined with no outlet for fluid excretion, preventing massive discharge; flame light窜 upward, causing sweat to surge upward as if steaming. The four limbs belong to the Spleen and should be harmonious and warm; they should not be too hot, nor particularly too cold. Whole-body heat with isolated coldness of hands and feet indicates fierce toxins suppressing Spleen Yang, preventing pathogen penetration; this is the manifestation of Cold due to Fire depression. Extreme cold is actually extreme heat. Before eruption, Ma Huang and Gui Zhi should be used to disperse, and Fire will naturally subside.