厥逆者，四肢不温，或甚至于冷也。四肢为诸阳之本，故常宜和暖，若至厥逆，则其阳虚
可知。如指尖微寒者，亦阳气衰也。足心冷者，乃阴邪胜也。其有疮头焦黑，烦渴闷顿，大
便热结而厥逆者，此阳毒内陷，火极似水，所谓热深厥亦深也。又有疮本灰白，大便不结
而厥逆者，此元气虚惫，阳衰而寒也。凡痘疹之候，头常欲凉，足常欲温，若头温足冷者多不
治，故厥逆为疮家恶候。
一、痘疹十指微寒者，即宜五君子煎、六气煎，或六物煎加姜、桂温之，以防虚寒之变。
一、痘疹泻利，气虚而逆者，胃关煎，或陈氏十二味异功散。
一、痘疮始出，手足便冷，或其人先有吐利，致伤脾胃，脾胃气虚则为厥逆，宜六气煎、
六物煎加姜、桂主之，甚者人参附子理阴煎。
一、痘疮起胀之时，手足厥逆，此阳气欲绝之候，必其自利或呕吐，脉见沉细微弱，或
浮大而虚，速宜温补元阳，轻则六气煎加肉桂，甚则六味回阳饮，或九味异功煎。服药后手足
和暖者生，厥不止者死。
一、热毒内甚而厥者，必有烦热便秘，胀满脉滑等证，宜四顺清凉饮，或承气汤。
一、痘后厥逆者，此其气血已虚，脾胃已困，无怪其有厥也，宜保元汤或六气煎、六物煎
加附、桂之类主之。
痘疹发渴者，里热也。以火起于内，销烁真阴，所以发渴。又其津液外泄，化马脓浆，
则营气虚耗，亦以致渴。此痘疮之常候也，若微渴不甚，不必治之。惟大渴者，乃由火盛，
然亦须察其虚实以为调理，切不可因其作渴，即以西瓜、梨、柿之类，轻以与之，恐脾
肺受寒，致生他患也。外有干渴，论在泄泻条中，所当参阅。
痘疮气血内耗，微热微渴而喜汤者，宜七味白术散，或五福饮加麦门冬、五味子。
一、脾肺多热，渴而喜冷者，宜人参麦门冬散，或生脉散。
一、痘疮多热多躁，口燥咽干，大渴引饮，喜冷能食，或大便干结者，此热在肺胃二经，
宜人参白虎汤，甚者再加黄连。若痘后热渴者，此余火未清也，其治亦然。
一、痘疮自利不止，肾阴亏损而作渴者，病作少阴，速宜陈氏十二味异功散，或九味异功煎。
一、大便秘结，腹满烦热，内火不清而作渴者，四顺清凉饮。
一、痘疮发热时，便见大渴，唇焦舌燥，此心火太炎，肾水不升，故血液枯耗也，急宜解之
，苡葛根解毒汤。
程氏曰∶痘疮初发之源，乃壬癸水也，水既流出，其源必竭，奚不作渴？由此观之，可见治
渴者，必不可不滋肾水。
薛氏曰∶凡渴欲饮水者，当审其热之虚实，若属虚热，虽欲水而不多饮，当用七味白术散；
若系实热，索水喜饮者，当以犀角磨水服，其后亦无余毒之患。
厥逆，是指四肢发凉，甚至冰冷。四肢是诸阳经的根本，所以应当保持温暖；如果发生厥逆，说明阳气虚弱。如果是指尖微微发凉，也是阳气衰弱的表现。足心发冷，则是阴邪盛行的结果。如果有疮疡顶部焦黑，伴有烦躁、口渴、神志昏闷，大便干结且出现厥逆的，这是阳毒内陷，火极似水，也就是所谓的“热深厥亦深”。又有疮色灰白，大便不干结而厥逆的，这是元气极度虚弱，阳气衰微导致的寒证。凡是痘疹的病症，头部通常希望凉爽，足部通常希望温暖；如果头温足冷，大多难以治愈，所以厥逆是疮疡家的凶险征候。
一、痘疹患者十指微凉的，应立即使用五君子煎、六气煎，或者在六物煎中加入生姜、肉桂来温补，以防虚寒病变的发生。
一、痘疹伴有腹泻，因气虚导致厥逆的，使用胃关煎，或者陈氏十二味异功散。
一、痘疮刚开始发出，手足就变冷，或者患者先前有呕吐腹泻，损伤了脾胃，导致脾胃气虚而出现厥逆的，宜用六气煎、六物煎加入生姜、肉桂为主治方；病情严重的，用人参附子理阴煎。
一、痘疮起胀阶段，出现手足厥逆，这是阳气即将断绝的征候，必然伴有自发性腹泻或呕吐，脉象沉细微弱，或者浮大而无根。此时必须迅速温补元阳，轻症用六气煎加肉桂，重症用六味回阳饮，或者九味异功煎。服药后手足回暖的预后良好，厥逆不止的预后不良（死亡）。
一、热毒内盛导致的厥逆，必然伴有烦躁发热、便秘、腹胀满、脉滑等症状，宜用四顺清凉饮，或者承气汤。
一、痘疮痊愈后出现厥逆的，这是因为气血已经虚弱，脾胃功能困顿，出现厥逆也不奇怪，宜用保元汤，或者六气煎、六物煎加入附子、肉桂等药物主治。
痘疹出现口渴的，是因为体内有热。因为火热生于内部，消耗真阴，所以导致口渴。另外，津液向外排泄，化为脓浆，导致营气虚耗，也会引起口渴。这是痘疮的常见症状，如果只是轻微口渴且不严重，不必治疗。只有大渴的，是由于火势旺盛，但也必须辨别虚实来进行调理，切不可因为患者口渴，就轻易给予西瓜、梨、柿子等寒凉食物，恐怕损伤脾肺，导致其他疾病。此外还有口干渴的情况，论述在泄泻条目中，应当参考阅读。
痘疮导致气血内部消耗，出现轻微发热、轻微口渴且喜欢喝热水的，宜用七味白术散，或者在五福饮中加入麦门冬、五味子。
一、脾肺多热，口渴且喜欢冷饮的，宜用人参麦门冬散，或者生脉散。
一、痘疮热象明显且烦躁，口燥咽干，大渴想喝水，喜欢冷饮且能进食，或者大便干结的，这是热邪在肺、胃二经，宜用人参白虎汤，病情严重的再加黄连。如果是痘疮后出现的发热口渴，这是余热未清，治疗方法也是如此。
一、痘疮自发性腹泻不止，因肾阴亏损而导致口渴的，病属少阴证，应迅速使用陈氏十二味异功散，或者九味异功煎。
一、大便秘结，腹部胀满，烦躁发热，因内火不清而导致口渴的，用四顺清凉饮。
一、痘疮发热时，立即出现大渴，嘴唇焦裂，舌头干燥，这是心火太旺，肾水不能上升，导致血液枯耗，急需解毒，用苡葛根解毒汤。
程氏说：痘疮初发的根源，在于壬癸水（肾水）；水既流出，源头必然枯竭，为何不出现口渴？由此看来，治疗口渴，一定不能不滋补肾水。
薛氏说：凡是想要饮水的口渴患者，应当审查热的虚实。如果属于虚热，虽然想喝水但饮水量不多，应当使用七味白术散；如果属于实热，索求饮水且喜欢喝的，应当用犀角磨水服用，其后也不会留下余毒的祸患。
Jue Ni (Reversal Cold) refers to the condition where the four limbs are cool, or even cold. The four limbs are the root of all Yang meridians; therefore, they should normally be warm and comfortable. If Jue Ni occurs, it indicates deficiency of Yang Qi. Slight coldness in the fingertips also signifies decline of Yang Qi. Coldness in the soles of the feet indicates an excess of Yin pathogenic factors. In cases where a sore has a blackened and scorched head, accompanied by irritability, thirst, mental confusion, constipation with hot accumulation, and Jue Ni, this is due to Yang toxin sinking inward. Extreme heat mimics water, which is referred to as "the deeper the heat, the deeper the Jue." Conversely, if the sore is grayish-white, stools are not dry, yet Jue Ni occurs, this is due to extreme exhaustion of Yuan Qi (Original Qi), resulting in cold from Yang decline. Generally, in the manifestations of smallpox/variolae, the head should prefer coolness while the feet should prefer warmth. If the head is warm but the feet are cold, it is often incurable; thus, Jue Ni is considered a ominous sign for patients with sores.
1. For variolae patients with slightly cold fingertips, Wujunzi Jian (Five Gentlemen Decoction) or Liuqi Jian (Six Qi Decoction) should be used immediately, or Liuwu Jian (Six Ingredients Decoction) added with Shengjiang (Zingiberis Rhizoma Recens, Fresh Ginger) and Rougui (Cinnamomi Cortex, Cinnamon Bark) to warm the body, preventing transformation into deficiency-cold pathology.
2. For variolae accompanied by diarrhea and Jue Ni due to Qi deficiency, Weiguan Jian (Stomach Gate Decoction) or Chen's Twelve-Ingredient Yigong San (Twelve-Ingredient Extraordinary Efficacy Powder) should be used.
3. When variolae first erupt, if the hands and feet become cold immediately, or if the patient previously suffered from vomiting and diarrhea damaging the Spleen and Stomach, leading to Spleen-Stomach Qi deficiency and subsequent Jue Ni, Liuwu Jian (Six Ingredients Decoction) or Liuqi Jian (Six Qi Decoction) added with Shengjiang (Zingiberis Rhizoma Recens, Fresh Ginger) and Rougui (Cinnamomi Cortex, Cinnamon Bark) should be the primary treatment. For severe cases, Renshen Fuzi Liyin Jian (Ginseng and Aconite Nourishing Yin Decoction) is indicated.
4. During the swelling stage of variolae, if Jue Ni of the hands and feet occurs, this is a sign that Yang Qi is about to perish. It must be accompanied by spontaneous diarrhea or vomiting, with a pulse that is deep, fine, weak, or floating, large, and empty. One must rapidly warm and tonify Yuan Yang (Original Yang). For mild cases, Liuqi Jian (Six Qi Decoction) added with Rougui (Cinnamomi Cortex, Cinnamon Bark); for severe cases, Liuwei Huiyang Yin (Six-Ingredient Returning Yang Decoction) or Jiawei Yigong Jian (Nine-Ingredient Extraordinary Efficacy Decoction). If the hands and feet become warm after taking the medicine, the prognosis is good; if Jue Ni persists, death ensues.
5. For Jue Ni caused by severe internal heat toxicity, there must be symptoms such as irritability, fever, constipation, abdominal fullness, and a slippery pulse. Sishun Qingliang Yin (Four-Obedience Clearing and Cooling Decoction) or Chengqi Tang (Chengqi Decoction) should be used.
6. For Jue Ni occurring after variolae, this is because Qi and Blood are already deficient and the Spleen and Stomach are exhausted; thus, Jue Ni is unsurprising. Baoyuan Tang (Protecting Origin Decoction), or Liuqi Jian (Six Qi Decoction)/Liuwu Jian (Six Ingredients Decoction) added with Fuzi (Aconiti Lateralis Radix Preparata, Prepared Lateral Root of Chinese Aconite) and Rougui (Cinnamomi Cortex, Cinnamon Bark) should be used.
Thirst in variolae is due to interior heat. Fire arising internally consumes Zhen Yin (True Yin), causing thirst. Additionally, when fluids leak outward to transform into pus and plasma, Ying Qi (Nutritive Qi) becomes depleted, also leading to thirst. This is a common manifestation of variolae. If the thirst is slight and not severe, no treatment is necessary. Only in cases of severe thirst, caused by excessive fire, must one differentiate between deficiency and excess to regulate treatment. One must absolutely avoid giving cold foods like watermelon, pear, or persimmon simply because the patient is thirsty, lest the Spleen and Lung suffer cold injury and generate other ailments. Dry thirst is discussed under the section on diarrhea and should be consulted.
When variolae deplete internal Qi and Blood, resulting in slight fever, slight thirst, and a preference for hot drinks, Qiwei Baizhu San (Seven-Ingredient Atractylodes Macrocephala Powder) or Wufu Yin (Five Blessings Decoction) added with Maidong (Ophiopogonis Radix, Ophiopogon Root) and Wuweizi (Schisandrae Chinensis Fructus, Schisandra Fruit) should be used.
1. For Spleen-Lung heat causing thirst with a preference for cold drinks, Ren Shen Maidong San (Ginseng and Ophiopogon Powder) or Sha Mai San (Pulse-Nourishing Powder) should be used.
2. For variolae with significant heat and restlessness, dry mouth and throat, severe thirst with desire to drink, preference for cold food/drink, ability to eat, or dry constipation, this indicates heat in the Lung and Stomach meridians. Ren Shen Baihu Tang (Ginseng White Tiger Decoction) should be used; for severe cases, add Huanglian (Coptidis Rhizoma, Coptis Rhizome). If fever and thirst occur after variolae, this is residual fire not yet cleared, and the treatment is the same.
3. For continuous spontaneous diarrhea in variolae causing thirst due to Kidney Yin deficiency, the disease manifests as Shao Yin syndrome. Chen's Twelve-Ingredient Yigong San (Twelve-Ingredient Extraordinary Efficacy Powder) or Jiawei Yigong Jian (Nine-Ingredient Extraordinary Efficacy Decoction) should be used urgently.
4. For dry stool constipation, abdominal fullness, irritability, and heat, causing thirst due to unclear internal fire, Sishun Qingliang Yin (Four-Obedience Clearing and Cooling Decoction) should be used.
5. When severe thirst appears immediately during the fever phase of variolae, with cracked lips and dry tongue, this indicates excessive Heart Fire and failure of Kidney Water to ascend, leading to depletion of blood and fluids. Immediate detoxification is required using Yige Gen Jiedu Tang (Coix Seed, Kudzu Root, and Rehmannia Detoxifying Decoction).
Master Cheng stated: The origin of variolae lies in Ren-Gui Water (Kidney Water). Once this water flows out, its source must be exhausted; why does it not cause thirst? From this, we can see that treating thirst requires nourishing Kidney Water without fail.
Master Xue stated: For patients desiring to drink water due to thirst, one must examine whether the heat is deficiency-type or excess-type. If it is deficiency-heat, although the patient desires water, they will not drink much; Qiwei Baizhu San (Seven-Ingredient Atractylodes Macrocephala Powder) should be used. If it is excess-heat, and the patient seeks water and likes to drink, Xi Jiao (Rhinocerotis Cornu, Rhino Horn - *Note: Modern substitutes like Shui Niu Jiao are used*) ground in water should be administered, after which there will be no risk of residual toxins.