不下通于阴。所以剂颈以下不能得汗。设见衄血。则邪从衄解。头间且无汗矣。设有汗则从汗解。又不衄矣。后条火邪
深入必圊血一证。亦谓身体枯燥而不得汗。必致圊血。设有汗。更不圊血矣。岂有得汗而反加衄血。圊血之理哉。又岂
有偏身无汗。而头汗为亡阳之理哉。
太阳病二日烦躁反熨其背。而大汗出。火热入胃。胃中水竭躁烦必发谵语。十余日振栗自下利者。此为欲解也。故
其汗从腰以下不得汗。欲小便不得。反呕欲失溲。足下恶风。大便硬。小盒饭数而反不数。及多大便已。头卓然而痛。
其人足心必热谷气下流故也。
火邪入胃十余日不解忽振栗自下利者火邪从大肠下奔。其候本为欲解。然而不得解者。以从腰以下不得汗。邪虽下
走终不外走故不解也上条从头以下不得汗。其势重。此条从腰以下不得汗。其势较轻。足下恶风者。见阳邪在下也。小
便不得。见阳邪闭拒阴窍也。与不得汗正同。所以大便亦硬。益见前之下利。为火势急奔。火势衰灭则利止也。反呕者。
邪欲从上越也。欲失泄者邪欲从阴出也。皆余邪未散之征。胃火既灭。小盒饭数。复不数。则津液可回。及至津回肠润。
则久积之大便必尽出。大便出多。则小便之当数者。始数矣。肠胃之间。邪热既散而不持。则腰以下之得汗。并可知矣。
得汗。则阴分之阳邪尽从汗解然后身半以下之阴气得上而反头痛身半以上之阳气得下而反足心热欲解之候。尚且如此。
火邪明虐为何如哉。
太阳病以火薰之不得汗。其人必躁到经不解。必清血名为火邪。（清圊同）
火邪入胃。胃中多水液者必速迫下利若胃中少津液之人复受火邪。则必加闷乱不宁。由是深入血室而为圊血也。盖
阳邪不解。得以袭入阴中。动其阴血。倘阳邪不尽。其圊血必无止期。故申之曰火邪。示人以治火邪而不治其血也。
微数之脉。慎不可灸。因火为邪则为烦逆迫虚逐实血散脉中。火气虽微内攻有力。焦骨阳筋。血难复也。
脉微而数。阴虚多热之征也。此而灸之。则虚者益虚。热者益热不至伤残不止耳。
烧针令其汗。针处被寒。核起而赤者。必发奔豚。气从小腹上冲心者。灸其核上。各一壮。与桂枝加桂汤。更加桂
二两。
奔豚者。肾邪也。北方肾邪惟桂能伐。所以用桂三倍。加入桂枝汤中。以外解风邪能泄阴气也。
形作伤寒。其脉不弦紧而弱。弱者必渴。被火者必谵语。弱者发热。脉浮解之当汗出愈。
形作伤寒。东垣所谓劳力感寒是也以其人本虚。故脉不弦紧而弱。渴者津液本少。不能胜邪也。被火者谵语。火气
伤阴。阳神悖乱也。弱者发热更伤阴血也。被火后脉不数疾而反浮。知邪未入里犹宜汗解以和表。则火邪亦得外散矣设
见数疾。当兼分利渗泄。具见言外。
太阳伤寒者。加温针必惊也。
温针攻寒。营血得之。更增其热营气通于心引热邪上逼神明。必致惊惶神乱也。
脉浮宜以汗解。用火炙之。邪无从出因火而盛。病从腰以下。重而痹。名火逆也。
外邪挟火势上逆。而不下通阴分。故重而痹也。
脉浮热甚。反炙之。此为实。实以虚治。因火而动。必咽燥唾血。
热甚为表实。反以火助其热。热剧迫血上行。故咽燥唾血也。
伤寒脉浮。医以火迫劫之。亡阳必惊狂。起卧不安者。桂枝去芍药。加蜀漆龙骨牡蛎。救逆汤主之。
火迫惊狂。起卧不安者。火邪于心。神明散乱也。夫神散正欲其收。何桂枝方中。反去芍药而增蜀漆龙骨牡蛎耶。
盖阳邪散乱。当求之于阳。桂枝汤阳药也。然必去芍药之阴重。始得疾达阳位。加蜀漆之性最急者。以迅扫其阴中之邪。
更加龙骨牡蛎以镇固阴中之怯也。
火逆下之。因烧针烦躁者。桂枝甘草龙骨牡蛎汤主之。
此证误而又误。虽无惊狂等证然烦躁则外尽之候也。亦真阳欲亡之机故用桂枝以解其外龙骨牡蛎以安其内不用蜀漆
者。阴中火邪未至逆乱无取急迫以滋扰害也。
营气微者。加烧针则血流不行。更发热而躁烦也。
营虚之人。即有寒伤营。营卫俱伤证并宜小建中和之慎不用麻黄青龙发汗。汗剂尚不可用况烧针乎。设误用烧针劫
汗。则血得火邪。必随外至卫分故曰加烧针。则血流。少顷热并于节不能内荣。故曰不行所以卫愈旺而营愈衰更加发热
躁烦势所必至也。
或问火逆。何不分营。卫以火为阳邪。必伤阴。血治此者。但当救阴为主。不必问其风寒营卫也。
以上火逆证
汗液不能通达于阴分，因此颈部以下无法出汗。如果出现鼻衄（鼻出血），则邪气随衄血而解，头部之间也就没有汗了。如果已经有汗出，则邪气随汗而解，就不会出现衄血了。后文提到的火邪深入必然导致便血这一证候，也是指身体干枯燥热而无汗，必然导致便血；如果有汗出，就更不会发生便血了。哪里有已经出汗反而加重鼻衄、便血的道理呢？又哪里有全身无汗，唯独头汗出却是亡阳的道理呢？
太阳病发病两天，患者烦躁，医生反而用熨背法治疗，导致大汗出。火热之邪入胃，胃中津液枯竭，躁烦必然引发谵语（胡言乱语）。过了十多天，患者出现振栗并自行下利，这是病情将要解除的征兆。所以，其腰部以下不得汗出，想要小便却排不出，反而呕吐，想要失禁，脚底怕冷，大便干硬，小便次数多但脉象并不数急，等到大量大便排出后，头部突然感到疼痛，这是因为人体正气（谷气）下行流通的缘故。
火邪入胃，十多天不解，忽然出现振栗并自行下利的，是火邪从大肠向下奔泄。这种征候本来是病情欲解的表现。然而之所以未能完全解除，是因为腰部以下不得汗出，邪气虽然向下走，终究不能向外透散，所以不能解除。上一条条文是从头部以下不得汗出，病势较重；这一条是从腰部以下不得汗出，病势较轻。脚底怕冷，说明阳邪在下部。小便排不出，说明阳邪闭阻阴窍。这与不得汗出的机理相同，所以大便也干硬。这更加印证了之前的下利，是由于火势急迫奔泄所致；火势衰灭，下利就会停止。反而呕吐，说明邪气欲从上越而出；想要失禁，说明邪气欲从阴窍而出。这些都是余邪未散的征象。胃火既然熄灭，小便次数由多变少，复而不数，那么津液就可以恢复。等到津液回复，肠道滋润，那么久积的大便必然会全部排出。大便排出较多，那么原本应该数急的小便，才开始变得正常。肠胃之间的邪热既已消散而不滞留，那么腰部以下能够出汗，也可以推知了。能够出汗，则阴分中的阳邪全部随汗而解。然后，身半以下的阴气得以向上运行而反致头痛，身半以上的阳气得以向下运行而反致足心发热，这是病情欲解的征候。尚且如此，火邪的肆虐程度可想而知。
太阳病用火熏法治疗，不得汗出，患者必然烦躁。如果到经气传变之日仍不解，必然导致便血，这称为火邪。（“清”与“圊”同义，指排便）
火邪入胃，如果胃中水液充足，必然迅速逼迫导致下利；如果是胃中津液不足的人，再受火邪，则必然加重闷乱不宁。由此火邪深入血室而导致便血。因为阳邪不解，得以侵入阴分，扰动阴血。倘若阳邪不尽，其便血必定没有止期。所以重申这是火邪，以提示人们治疗火邪应当治火而不是单纯治血。
脉象微而数，千万不可使用灸法。因为火本身即为邪气，会导致烦逆。火邪逼迫虚处，追逐实处，使血液散乱于脉中。火气虽然微弱，但内攻之力强大，会焦灼骨骼筋脉，血液难以恢复。
脉微而数，是阴虚内热的征象。对此进行灸治，则虚者更虚，热者更热，不到伤残的地步是不会停止的。
烧针令其发汗，针孔处受寒，红肿如核且发红，必然引发奔豚（一种气从小腹上冲心胸的病证）。气从小腹上冲至心脏的，在红肿处各灸一壮，并给予桂枝加桂汤，多加桂二两。
奔豚属于肾邪。北方的肾邪唯有桂能伐除，所以使用三倍量的桂，加入桂枝汤中，以外解风邪，并能泄除阴气。
症状表现像伤寒，但其脉象不弦紧而弱。脉弱者必然口渴，被火法治疗后必然出现谵语。脉弱伴有发热，脉浮，应当用汗法解表，汗出即可痊愈。
症状像伤寒，即东垣所说的劳力感寒。因为患者本身体虚，所以脉象不弦紧而弱。口渴是因为津液本少，不能胜邪。被火法治疗后出现谵语，是因为火气伤阴，阳神悖乱。脉弱发热更伤阴血。被火法治疗后，脉象不数疾反而浮，可知邪气未入里，仍然适宜用汗法解表以调和营卫，这样火邪也能随之外散。如果见到脉数疾，应当兼用分利渗泄之法，这些都在言外之意中体现。
温针攻逐寒邪，营血得到温通，反而增加其热。营气通于心，引动热邪上逼神明，必然导致惊惶神乱。
脉浮适宜用汗法解表，如果用火炙法，邪气无从出路，因火而邪盛，病见腰部以下沉重而麻木，称为火逆。
外邪挟带火势上逆，而不能向下通达阴分，所以沉重而麻木。
脉浮且热势很盛，反而用灸法，这是实证。以虚法治实证，因火而动血，必然导致咽干唾血。
伤寒脉浮，医生用火法强迫发汗，导致亡阳，必然出现惊狂、起卧不安的症状，用桂枝去芍药加蜀漆龙骨牡蛎救逆汤主治。
火迫导致惊狂、起卧不安，是火邪扰心，神明散乱。神气散乱正需要收敛，为什么桂枝方中反而去掉芍药而增加蜀漆、龙骨、牡蛎呢？因为阳邪散乱，当从阳分求治。桂枝汤是阳药，但必须去掉芍药的阴重之性，才能迅速到达阳位。加上性质最急的蜀漆，以迅扫阴中之邪；再加龙骨、牡蛎以镇固阴中之怯。
此证误而又误，虽然没有惊狂等证，但烦躁则是邪气未尽的征候，也是真阳欲亡的机转。所以用桂枝以解其外，龙骨牡蛎以安其内。不用蜀漆的原因是，阴中火邪未至逆乱，不需要急迫之品以免滋扰伤害。
营虚之人，即使有寒伤营、营卫俱伤的证候，也宜用小建中汤调和，慎用麻黄、青龙等发汗剂。汗剂尚且不可用，何况烧针呢？如果误用烧针劫汗，则血得火邪，必然随外邪至于卫分，所以说加烧针则血流；稍后热并于节，不能内荣，所以说不行。所以卫气愈旺而营气愈衰，再加上发热躁烦，是势必发生的。
有人问：火逆证，为什么不区分营、卫？因为火为阳邪，必然伤阴血。治疗此证，只应当以救阴为主，不必问其是风寒还是营卫。
以上是火逆证。
Sweat cannot penetrate to the Yin aspect, therefore sweat cannot be obtained below the neck. If epistaxis (nosebleed) occurs, then the pathogen is resolved through bleeding, and there will be no sweat on the head. If sweat has already occurred, then the pathogen is resolved through sweating, and epistaxis will not happen. The later clause mentions that fire pathogen penetrating deeply inevitably leads to hematochezia (blood in stool), which also refers to the body being dry and devoid of sweat, inevitably causing hematochezia; if sweat occurs, hematochezia will certainly not happen. How could there be a principle where sweating exacerbates epistaxis or hematochezia? And how could there be a principle where the whole body has no sweat, yet head sweat indicates Yang collapse?
In Taiyang disease, after two days, if the patient is irritable and the doctor instead applies hot compresses to the back, causing profuse sweating, the fire-heat enters the Stomach. With the exhaustion of fluids in the Stomach, irritability will inevitably lead to delirious speech (delirium). After more than ten days, if the patient experiences tremors and spontaneous diarrhea, this indicates the disease is about to resolve. Thus, sweat cannot be obtained from the waist down; the desire to urinate is present but unsuccessful, accompanied by vomiting and a sensation of incontinence, aversion to wind at the soles of the feet, hard stools, frequent urination but a pulse that is not rapid, and until large amounts of stool are passed, sudden pain in the head occurs. This is because the Qi of grain (Gu Qi) flows downward.
When the fire pathogen enters the Stomach and remains unresolved for over ten days, sudden tremors and spontaneous diarrhea indicate that the fire pathogen is rushing down through the Large Intestine. This presentation originally suggests the disease is resolving. However, it fails to resolve because sweat cannot be obtained from the waist down; although the pathogen moves downward, it ultimately does not exit outwardly, hence it does not resolve. In the previous clause, lack of sweat from the head downward indicated a severe condition; here, lack of sweat from the waist downward indicates a milder condition. Aversion to wind at the soles indicates Yang pathogen in the lower part. Inability to urinate indicates Yang pathogen obstructing the Yin orifices, similar to the inability to sweat, which also causes hard stools. This further confirms that the previous diarrhea was due to the urgent rush of fire heat; when the fire heat subsides, the diarrhea stops. Vomiting indicates the pathogen desires to escape upward; the sensation of incontinence indicates the pathogen desires to exit through the Yin orifices. These are all signs of residual pathogen not yet dispersed. Once the Stomach fire extinguishes, the frequency of urination decreases and becomes normal again, allowing fluids to return. When fluids return and the intestines moisten, accumulated stool will be expelled. As much stool is expelled, the urine frequency, which should have been rapid, finally becomes normal. Between the stomach and intestines, once the pathogenic heat dissipates and does not linger, it can be inferred that sweat will be obtained below the waist. Obtaining sweat means all Yang pathogens in the Yin aspect are resolved through sweating. Then, Yin Qi from below the half-body rises upward, causing headache, while Yang Qi from above the half-body descends downward, causing heat in the soles of the feet. Even in this state of resolution, such symptoms occur; thus, the severity of the fire pathogen's tyranny can be imagined.
If Taiyang disease is treated with moxibustion/fumigation without obtaining sweat, the patient will become irritable. If the disease does not resolve upon the completion of the meridian cycle, hematochezia (blood in stool) will definitely occur, termed "Fire Pathogen" ("Qing" is synonymous with "Qing", referring to defecation).
If the fire pathogen enters the Stomach and there is abundant fluid in the Stomach, it will rapidly force diarrhea. However, if a person with deficient Stomach fluids receives fire pathogen, it will worsen mental confusion and restlessness. Consequently, the pathogen penetrates deeply into the Blood Chamber, causing hematochezia. Because the Yang pathogen is not resolved, it invades the Yin, disturbing Yin blood. If the Yang pathogen is not completely exhausted, the hematochezia will have no end. Therefore, it is emphasized as "Fire Pathogen" to instruct practitioners to treat the fire rather than just the blood.
A pulse that is faint and rapid must never be treated with moxibustion. Since fire itself is a pathogen, it causes vexation and rebellion. Fire forces deficiency and pursues excess, scattering blood within the vessels. Although the fire energy is slight, its internal attack is powerful, scorching bones and sinews, making blood difficult to restore.
A faint and rapid pulse is a sign of Yin deficiency with internal heat. Applying moxibustion here makes the deficient even more deficient and the hot even hotter, continuing only until injury and disability occur.
If pricking needles induces sweating, and the needle site is exposed to cold, resulting in nodules rising and turning red, Ben Tun (panicking pig syndrome, characterized by Qi rushing from the lower abdomen to the heart) will definitely develop. For Qi rushing from the lower abdomen to the heart, apply one moxa cone on each nodule, and administer Guizhi Jia Gui Tang (Cinnamon Twig Decoction plus Cinnamon), adding two liang of Cinnamon Twig.
Ben Tun is a Kidney pathogen. Only Cinnamon can subdue the Northern Kidney pathogen; therefore, three times the amount of Cinnamon is used, added to Guizhi Tang, to externally resolve Wind pathogen and vent Yin Qi.
The presentation resembles Shaoyang disease, but the pulse is not wiry and tight; instead, it is weak. A weak pulse implies thirst. If treated with fire methods, delirious speech will definitely occur. Weakness with fever: if the pulse is floating, it should be resolved with sweating, and recovery follows with sweat.
Presentation resembling Shaoyang disease refers to what Dong Yuan called "labor-induced cold invasion." Because the person is originally deficient, the pulse is not wiry/tight but weak. Thirst indicates originally scant fluids unable to overcome the pathogen. Delirium after fire treatment indicates fire injuring Yin and confusing the Shen (Spirit). Weakness with fever further injures Yin blood. After fire treatment, if the pulse is not rapid but floating, it indicates the pathogen has not entered the interior and still requires sweating to harmonize the exterior, allowing the fire pathogen to scatter outward. If a rapid pulse appears, draining and leaching methods should be combined, as implied.
In Taiyang Cold Damage, applying warm needles will definitely cause fright.
Warm needles attack cold; Ying (Nutritive) blood is affected, increasing heat. Ying Qi connects to the Heart, drawing heat pathogen upward to oppress the Shen (Spirit), inevitably causing panic and mental disorder.
A floating pulse should be resolved with sweating. If moxibustion is applied, the pathogen has no outlet, intensifying due to fire. The disease manifests as heaviness and numbness below the waist, termed "Fire Reversal" (Huo Ni).
Exterior pathogen carrying fire heat reverses upward and cannot penetrate downward to the Yin aspect, causing heaviness and numbness.
Floating pulse with intense heat, treated with moxibustion, constitutes an Excess pattern. Treating Excess as Deficiency, agitation by fire will inevitably cause dry throat and spitting of blood.
Intense heat indicates Exterior Excess; using fire to assist heat drives blood upward violently, causing dry throat and spitting of blood.
In Cold Damage with a floating pulse, if the physician uses fire to force sweating, causing Yang collapse, symptoms of panic, mania, restlessness, and inability to lie still will occur. Treat with Guizhi Qu Shaoyao Jia Shuqi Longgu Muli Jiuni Tang (Cinnamon Twig Decoction minus Peony plus Chinese Dodder Root, Dragon Bone, and Oyster Shell Rescue Reversal Decoction).
Panic, mania, and restlessness caused by fire forcing sweating indicate fire pathogen affecting the Heart and scattering the Shen. Since the Shen is scattered and needs gathering, why remove Shaoyao (Peony) and add Shuqi (Chinese Dodder Root), Longgu (Dragon Bone), and Muli (Oyster Shell) in the Guizhi formula? Because Yang pathogen is scattered, it must be sought in the Yang aspect. Guizhi Tang consists of Yang herbs. Removing the heavy Yin nature of Shaoyao allows rapid access to the Yang position. Adding Shuqi, which has the most urgent nature, swiftly sweeps away pathogen in the Yin. Adding Longgu and Muli stabilizes and anchors the timidity in the Yin.
If Fire Reversal is followed by purgation, and prickling needles cause irritability, treat with Guizhi Gancao Longgu Muli Tang (Cinnamon Twig and Licorice Decoction with Dragon Bone and Oyster Shell).
This case involves repeated errors. Although there are no symptoms like panic or mania, irritability indicates the exterior pathogen is not fully resolved and signals the potential collapse of True Yang. Therefore, Guizhi is used to resolve the exterior, and Longgu/Muli to calm the interior. Shuqi is omitted because the fire pathogen in the Yin has not reached chaotic levels, avoiding the need for urgent agents that might cause disturbance.
In persons with weak Ying Qi, adding prickling needles causes blood flow to stagnate, leading to recurrent fever and irritability.
In those with Ying deficiency, even if there is Cold damaging Ying and both Ying and Wei being damaged, Xiaojianzhong Tang (Minor Construct the Middle Decoction) should be used to harmonize. Ma Huang Tang and Qinglong Tang (Ephedra Decoction and Green Dragon Decoction) for sweating should be used cautiously. Even sweat-inducing formulas are inadvisable, let alone prickling needles. If prickling needles are mistakenly used to force sweat, blood, affected by fire, will move to the Wei (Defensive) level. Thus, it is said prickling needles cause blood movement. Shortly after, heat concentrates at the joints and cannot nourish internally, hence "not moving." Thus, Wei becomes vigorous while Ying declines, and recurrent fever and irritability are inevitable.
One may ask: Why is Fire Reversal not differentiated by Ying and Wei? Because fire is a Yang pathogen, it inevitably injures Yin blood. Treatment should focus primarily on rescuing Yin, regardless of whether it is Wind-Cold or Ying/Wei imbalance.
Above are the cases of Fire Reversal.