本发汗而复下之此为逆也若先发汗治不为逆先本下之而复汗之为逆若先下之治不为逆
申明上章逆字之义风寒外闭宜辛温发散而不宜下燥热内结宜苦寒攻下而不宜汗若表邪未解里邪复盛则宜先汗而后下
若里邪急迫表邪轻微则宜先下而后汗错则成逆矣若治法得宜先后不失不为逆也
阳明从燥金化气阳旺之人表郁则燥动然不经误治津液未耗燥气之作何至遽盛及其汗下温针伤津亡液燥气大发经腑合
邪乃成下证虽不如三阴之险然阴亏阳亢亦伏危机未可率然也
太阳病先发汗不解而复下之脉浮者不愈浮为在外而反下之故令不愈今脉浮故知在外当须解外则愈桂枝汤主之（方在
太阳五）
太阳病先发汗不解而复下之设内有腑热则下之当愈若使脉浮则表邪未解必不能愈以浮为邪在表遗其外邪而反下之故
令不愈当须解外则愈宜主桂枝也 此太阳表证未罢而内有腑证固当下也然必外解而后可下若发汗未解而遽下之设脉犹见
浮则外必不愈故仍以桂枝解外
大下之后复发汗小便不利者亡津液故也勿治之得小便利必自愈
膀胱者州都之官津液藏焉气化则能出矣土湿金郁气不化水土湿木郁不能行水皆令小便不利小青龙五苓散证之小便不
利悉缘土湿而水停则小便之不利必因湿旺若汗下之后而见小便之不利是津液亡泄燥而非湿也然别无热渴之证则其燥未甚
勿用治之俟其津液续复得小便一切必自愈也汗下之后小便不利阳虚之人则阳亡而病湿阴虚之人则阴亡而伤燥此不见阳亡
湿动之证故知是亡津伤燥也此亦人参白虎证而燥热未作则病势最轻故不须治之
原本应当发汗却反而使用攻下法，这是逆治；如果先进行发汗治疗，则不视为逆治。原本应当使用攻下法却反而先发汗，这也是逆治；如果先进行攻下治疗，则不视为逆治。
在此阐明前章中“逆”字的含义：风寒之邪闭塞体表，适宜用辛温药物发散，而不宜使用攻下法；燥热之邪结聚于体内，适宜用苦寒药物攻下，而不宜使用发汗法。如果表邪尚未解除，而里邪又变得强盛，则应当先发汗而后攻下。如果里邪急迫而表邪轻微，则应当先攻下而后发汗。治疗顺序颠倒就会造成逆证。如果治疗方法得当，先后次序无误，就不称为逆治。
阳明经从燥金之气化生，阳气旺盛的人，若体表郁闭，则体内的燥气会随之发动。然而，如果没有经过误治导致津液耗损，燥气怎么会突然变得强盛呢？若是经过发汗、攻下或温针等疗法损伤了津液、耗尽了阴液，导致燥气大发，经络与脏腑同时受邪，这才形成了可下的证候。虽然这不像三阴病那样危险，但阴液亏损、阳气亢盛也潜伏着危机，不可轻率对待。
太阳病（太阳经受邪所致的病证），先发汗后症状未解，又转而使用攻下法，如果脉象仍然浮起，说明病仍未愈。脉浮表示病邪仍在体表，反而使用攻下法，所以导致病情未愈。如今脉象仍为浮脉，因此知道病邪仍在体表，应当通过解除表邪来治愈，主方用桂枝汤（Cinnamon Twig Decoction）。（该方剂见太阳五）
太阳病，先发汗后症状未解，又转而使用攻下法。假设体内有腑热，那么攻下法应当能治愈；但如果脉象依然浮起，说明表邪尚未解除，必定不能痊愈。因为脉浮代表邪气在表，遗漏了体表的邪气反而使用攻下法，所以导致病情未愈。此时应当通过解除表邪来治愈，适宜主用桂枝汤。这是太阳表证尚未罢除，而体内又有腑证的情况，本来应当使用攻下法，但必须等到表证解除后才能攻下。如果发汗后表证未解就急于攻下，假设脉象仍然表现为浮脉，那么表外必定不能痊愈，所以仍以桂枝汤解除表邪。
在大面积攻下之后，再次发汗，出现小便不通利的情况，这是因为津液亡失的缘故。不要对此进行治疗，待小便自然通利，疾病必自愈。
膀胱（Bladder）是州都之官，负责贮藏津液，只有经过气化作用才能排出尿液。脾土湿气重、肺金郁滞，导致气机不化；水土湿盛、肝木郁滞，导致水液运行不畅，这些都会导致小便不利。小青龙汤（Minor Blue Dragon Decoction）和五苓散（Five-Ingredient Powder with Poria）所主治的小便不利，都是由于脾土湿盛而导致水液停聚。如果是这种情况，小便不利必然因湿邪旺盛所致。然而，如果在发汗、攻下之后出现小便不利，这是津液亡泄导致的干燥，而非湿邪。如果没有其他热渴的症状，说明燥热并不严重，不要使用药物治疗。等待津液逐渐恢复，小便自然通利，疾病必自愈。在发汗、攻下之后出现小便不利，对于阳气虚弱的人，会导致阳亡而病生湿邪；对于阴液虚弱的人，会导致阴亡而损伤燥气。此处没有见到阳亡湿动的证候，因此知道这是津液亡失、损伤燥气的表现。这也属于人参白虎汤（Ginseng and White Tiger Decoction）的范畴，但由于燥热尚未发作，病势最轻，所以不需要治疗。
Originally, sweating should have been induced, but purgation was applied instead; this is a contraindicated approach (Ni). If sweating is induced first, the treatment is not contraindicated. Originally, purgation should have been applied, but sweating was induced first; this is also a contraindicated approach. If purgation is applied first, the treatment is not contraindicated.
This clarifies the meaning of "contraindicated" (Ni) mentioned in the previous chapter: When wind-cold pathogens close the exterior, acrid-warm dispersing methods are appropriate, while purgation is inappropriate. When dry-heat pathogens bind internally, bitter-cold purging methods are appropriate, while sweating is inappropriate. If the exterior pathogen is unresolved and the interior pathogen becomes vigorous, one should induce sweating first and then purge. If the interior pathogen is urgent while the exterior pathogen is slight, one should purge first and then induce sweating. Reversing this order results in a contraindicated condition. If the treatment method is appropriate and the sequence is correct, it is not considered contraindicated.
The Yangming channel transforms according to the Qi of Dry Metal. In individuals with vigorous Yang, if the exterior is constrained, the internal dryness will stir. However, without mismanagement causing fluid consumption, how could the dryness suddenly become vigorous? Only after sweating, purgation, or warm needle therapy damages the fluids and exhausts the Yin, causing dryness to flare up significantly, do the channels and fu-organs simultaneously suffer from pathogens, forming a condition requiring purgation. Although not as perilous as Shaoyin diseases, Yin deficiency with Yang hyperactivity harbors hidden crises, so one must not act rashly.
In Taiyang disease (Disease of the Taiyang Channel), if sweating is induced first but symptoms persist, and purgation is subsequently applied, and the pulse remains floating, the disease is not cured. A floating pulse indicates the pathogen is still at the exterior. Applying purgation against this causes the disease to remain uncured. Since the pulse is currently floating, we know the pathogen is still at the exterior; thus, resolving the exterior will lead to recovery. Guizhi Tang (Cinnamon Twig Decoction) should be administered. (See Taiyang 5 for the formula.)
In Taiyang disease, if sweating is induced first but symptoms persist, and purgation is subsequently applied: assuming there is heat in the fu-organs internally, purgation should cure it. However, if the pulse remains floating, it indicates the exterior pathogen is unresolved, and recovery is impossible. Because a floating pulse signifies the pathogen is at the exterior, neglecting the exterior pathogen while applying purgation causes the disease to remain uncured. One must resolve the exterior to achieve recovery, and Guizhi Tang is appropriate. This describes a situation where the Taiyang exterior syndrome has not yet ceased, while an interior fu-organ syndrome exists, which inherently requires purgation. However, purgation can only be performed after the exterior is resolved. If purgation is hastily applied before the exterior resolves, and the pulse still appears floating, the exterior will certainly not heal; therefore, Guizhi Tang should still be used to resolve the exterior.
After severe purgation followed by sweating, if urination is difficult, it is due to the loss of body fluids. Do not treat this directly; when urination naturally becomes smooth, the disease will self-resolve.
The Bladder is the official of the capital region, storing fluids. It can discharge them only through Qi transformation. Dampness in Spleen Earth and stagnation in Lung Metal prevent Qi transformation. Water-Earth dampness and Liver Wood stagnation hinder water movement, all leading to difficulty in urination. The difficulty in urination treated by Xiao Qing Long Tang (Minor Blue Dragon Decoction) and Wu Ling San (Five-Ingredient Powder with Poria) stems entirely from Spleen Earth dampness causing water retention. In such cases, difficulty in urination is caused by excessive dampness. However, if difficulty in urination occurs after sweating and purgation, it is due to fluid loss causing dryness, not dampness. If there are no other signs of heat and thirst, the dryness is not severe. Do not use medication. Wait for the fluids to gradually recover; once urination becomes smooth, the disease will self-resolve. After sweating and purgation, difficulty in urination affects those with Yang deficiency by causing Yang collapse and damp pathology, and affects those with Yin deficiency by causing Yin collapse and dryness pathology. Here, since there are no signs of Yang collapse with dampness stirring, we know this is fluid loss causing dryness injury. This also falls under the category of Renshen Baihu Tang (Ginseng and White Tiger Decoction), but since dry-heat has not yet manifested, the pathological trend is mildest, so treatment is unnecessary.