病发热头痛。脉反沉。若不瘥。身体疼痛。当救其里。宜四逆汤。
发热身疼痛。邪在表也。而脉反沉。则脉与病左矣。不瘥者。谓以汗药发之而不瘥也。以其里
气虚寒。无以为发汗散邪之地。故与四逆汤。舍其表而救其里。如下利身疼痛之例也。
四逆汤方
生附子（一枚） 干姜（一两半） 炙甘草（二两）
上三味 咀。以水三升。煮取一升二合。去滓。分温再服。强人可大附子一枚。干姜三两。
太阳病未解。脉阴阳俱停。必先振栗汗出而解。但阳脉微者。先汗出而解。但阴脉微者。下之
而解。若欲下之。宜调胃承气汤主之。
脉阴阳俱停者。阴阳诸脉。两相停匀。而无偏胜也。既无偏胜。则必有相持不下之势。故必
至于战而汗出。而后邪气乃解。振栗者。阴阳相争之候也。但阳脉微者。阳邪先衰。故当汗出而解。
但阴脉微者。阴邪先衰。故可下之而解。所谓攻其坚而不入者。攻其瑕而立破也。然本论云、尺中脉
微者。不可下。此又云、但阴脉微者。下之而解。盖彼为正虚而微。此为邪退而微也。脉微则同。
而辨之于邪与正之间。亦未易言之矣。调胃承气乃下药之最轻者。以因势利导。故不取大下而取缓
行耳。夫伤寒先汗后下者。法之常也。或先汗或先下。随脉转移者。法之变也。设不知此而汗下
妄施。宁不为逆耶。
调胃承气汤方
大黄（四两去皮） 炙甘草（二两） 芒硝（半斤）
上三味。以水三升。煮取一升。去滓。纳芒硝。更上火微煮令沸。少少温服之。
病人出现发热、头痛的症状，脉象反而呈现沉象。如果病情没有好转，身体依然疼痛，应当先救治里证，适宜使用四逆汤。
发热且身体疼痛，说明邪气在表。但脉象反而沉，说明脉象与病证不符（脉证相左）。所谓“不瘥”，是指使用发汗药治疗后病情仍未痊愈。这是因为患者里气虚寒，没有足够的正气作为发汗驱散邪气的根基，所以给予四逆汤，舍弃表证而先救里证，这类似于下利兼有身体疼痛时的处理原则。
四逆汤方剂组成：
生附子（一枚） 干姜（一两半） 炙甘草（二两）
以上三味药，切碎。用水三升，煮取一升二合的药液，滤去药渣。分两次温服。体质强壮的人可以使用大附子一枚，干姜三两。
太阳病尚未解除，寸关尺三部脉象都显得隐伏不出（停，此处指脉搏动微弱或暂时摸不到，并非停止），此时病人必定会出现战栗、出汗的现象，随后病邪得以解除。如果仅是阳脉（寸脉）微显，应当先通过发汗使病邪解除。如果仅是阴脉（尺脉）微显，应当通过泻下法使病邪解除。如果想要使用泻下法，适宜以调胃承气汤为主治方剂。
所谓“脉阴阳俱停”，是指阴阳各部脉象两相平衡均匀，没有偏盛偏衰的情况。既然没有偏胜，就必然存在正气与邪气相持不下的局势，所以必须等到正气奋起抗邪，出现战栗并出汗后，邪气才能解除。振栗是阴阳之气相互争斗的表现。如果是阳脉微，说明阳分之邪气先衰，所以应当通过发汗来解除病邪。如果是阴脉微，说明阴分之邪气先衰，所以可以通过泻下来解除病邪。这就是所谓的攻打坚固之处难以进入时，攻击其薄弱环节就能立刻攻破的道理。然而《伤寒论》原文中说：“尺中脉微者，不可下。”这里又说：“但阴脉微者，下之而解。”这是因为前者属于正气虚弱导致的脉微，后者属于邪气退却导致的脉微。虽然脉象都表现为微，但在邪气与正气的辨别上，其中的道理也不容易说清楚。调胃承气汤是泻下药中最轻缓的方剂，因为要顺应病势进行引导，所以不采用峻猛的大泻法，而采用缓行的方法。通常治疗伤寒是先发汗后泻下，这是常法；或者根据脉象变化决定先发汗还是先泻下，这是变法。如果不了解这些原则而妄自施用汗法或下法，难道不是造成逆证吗？
调胃承气汤方剂组成：
大黄（四两，去皮） 炙甘草（二两） 芒硝（半斤）
以上三味药，用水三升，煮取一升药液，滤去药渣，加入芒硝，再次放在火上微煮至沸腾，少量多次温服。
The patient presents with fever and headache. The pulse is unexpectedly deep (Chen, 沉). If the condition does not improve and body pain persists, the interior should be rescued first; Si Ni Tang (Four Reversal Decoction) is appropriate.
Fever accompanied by body pain indicates that the pathogenic factor is in the Exterior (Biao, 表). However, the pulse is unexpectedly deep, meaning the pulse contradicts the disease presentation. "Not improving" refers to the failure of the condition to resolve after treatment with diaphoretic herbs. This occurs because the Interior Qi is deficient and cold, lacking the sufficient Zheng Qi (Upright Qi, 正气) required as a foundation for sweating to disperse the pathogen. Therefore, Si Ni Tang is administered to abandon the Exterior and rescue the Interior, similar to the principle applied when diarrhea is accompanied by body pain.
Formula: Si Ni Tang (Four Reversal Decoction)
Sheng Fuzi (Raw Aconiti Lateralis Radix, one piece)
Gan Jiang (Dried Zingiberis Rhizoma, one tael and half)
Zhi Gancao (Honey-fried Glycyrrhizae Radix et Rhizoma, two taels)
Crush the above three ingredients. Boil in three sheng of water until reduced to one sheng and two he. Strain the dregs. Divide into two doses and take warm. For robust individuals, use one large Sheng Fuzi and three taels of Gan Jiang.
In Taiyang disease (Taiyang Bing, 太阳病) that has not yet resolved, if the pulses at the Yin (Cun/Kou positions, representing Interior/Exterior balance in this context often referring to depth/radial vs ulnar or cun/chest vs chi/abdomen, here interpreted as balanced but faint/stopped) are all "ting" (faint or imperceptible), the patient will inevitably experience chills and tremors followed by sweating, after which the pathogen will be resolved. If only the Yang pulse (Cun pulse, 寸脉) is slightly weak, resolution should be sought through sweating. If only the Yin pulse (Chi pulse, 尺脉) is slightly weak, resolution should be sought through purgation. If purgation is desired, Tiao Wei Cheng Qi Tang (Regulate the Stomach and Direct the Qi Decoction) is the primary formula.
"Pulses at Yin and Yang both ting" means the pulses across Yin and Yang positions are balanced and even, without excess or deficiency. Since there is no bias, there must be a stalemate between Zheng Qi and the pathogen. Thus, it is necessary to wait for the struggle between Yin and Yang energies, manifested as chills and tremors, followed by sweating, before the pathogen can be resolved. Chills and tremors are signs of the contention between Yin and Yang. If the Yang pulse is slightly weak, it indicates that the Yang-pathogen has declined first; therefore, resolution should be achieved through sweating. If the Yin pulse is slightly weak, it indicates that the Yin-pathogen has declined first; therefore, resolution can be achieved through purgation. This illustrates the principle that when attacking a fortified position fails, attacking its weakness leads to immediate collapse. However, the original text states: "If the Chi pulse is weak, purgation is contraindicated." Here it says: "If only the Yin pulse is weak, purgation resolves it." The former refers to weakness due to deficiency of healthy Qi, while the latter refers to weakness resulting from the retreat of the pathogen. Although both present as weak pulses, distinguishing between pathogen and healthy Qi is not easy. Tiao Wei Cheng Qi Tang is the mildest among purgative formulas; because it follows the momentum of the disease to guide it out, it avoids drastic purgation in favor of a gradual action. Typically, treating Shanghan involves sweating first and purging second; this is the constant method. Varying between sweating and purging based on pulse changes is the variable method. Ignoring these principles and administering sweating or purging recklessly would undoubtedly lead to adverse conditions.
Formula: Tiao Wei Cheng Qi Tang (Regulate the Stomach and Direct the Qi Decoction)
Da Huang (Rhubarb Root and Rhizome, four taels, peeled)
Zhi Gancao (Honey-fried Glycyrrhizae Radix et Rhizoma, two taels)
Mang Xiao (Mirabilite, half a jin)
Boil the above three ingredients in three sheng of water until reduced to one sheng. Strain the dregs. Add Mang Xiao. Heat again gently until boiling. Take small amounts warm.