附子（去皮，生破八片）二枚 茯苓三两 人参二两 白术四两 芍药三两
右五味，以水八升，煮取三升，去滓，温服一升，日三服。
【方解】
少阴为寒水之藏，故寒伤之重者、多入少阴，所以少阴一经，最多死证。方中君以附
子二枚者，取其力之锐，且以重其任也；生用者，一以壮少火之阳，一以散中外之寒
，则身痛自止，恶寒自除，手足自温矣。以人参为臣者，所以固生气之原，令五藏六
府有本，十二经脉有根，脉自不沉，骨节可和矣。更佐白术以培土，芍药以平木，茯
苓以伐水，水伐火自旺，旺则阴翳消，木平土益安，安则水有制，制则生化，此诚万
全之术也。其有畏而不敢用，以致因循有误者，不诚可惜哉！
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少阴病，脉沉者，急温之，宜四逆汤。
【注】
少阴病，但欲寐，脉沉者，若无发热、口燥之证，则寒邪已入其藏，不须迟疑，急温
之以四逆汤，消阴助阳可也。
【集注】
吴人驹曰：脉沉须别虚实，及得病新久，若得之多日及沉而实者，须从别论。
甘草（炙）二两 干姜一两半 附子（生用，去皮，破八片）一枚
右三味，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
。
【方解】
方名四逆者，主治少阴中外皆寒，四肢厥逆也。君以甘草之甘温，温养阳气；臣以姜
附之辛温，助阳胜寒；甘草得姜附，鼓肾阳温中寒，有水中暖土之功；姜、附得甘草
，通关节走四肢，有逐阴回阳之力，肾阳鼓，寒阴消，则阳气外达而脉自升，手足自
温矣。
【集解】
汪琥曰：少阴病，本脉微细，但欲寐。今轻取之，微脉不见，重取之，细脉几亡，伏
匿而至于沉，此寒邪深入于里，殆将入藏，温之不容以不急也。稍迟则恶寒身蜷，吐
利烦躁，不得卧寐，手足逆冷，脉不至，诸死证立至矣，四逆汤之用可稍缓乎？
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少阴病，下利，白通汤主之。
【注】
少阴病但欲寐，脉微细，已属阳为阴困矣。更加以下利，恐阴降极、阳下脱也。故君
以葱白，大通其阳而上升；佐以姜、附，急胜其阴而缓降，则未脱之阳可复矣。
【集注】
方有执曰：少阴病而加下利者，不独在经，而亦在藏寒甚而阴盛也。治之以干姜、附
子者，胜其阴则寒自散也。用葱白而曰白通者，通其阳则阴自消也。
程知曰：此言下利宜通其阳也。少阴病，谓有脉微细、欲寐证也。少阴下利，阴盛之
极，恐致格阳，故用姜、附以消阴，葱白以升阳。通云者，一以温之，而令阳气得入
；一以发之，而令阴气易散也。
汪琥曰：肾虚无火不能主水，故下利用白通汤者，温里以散寒也。
【附子汤方】
炮制好的附子（去掉外皮，生用，破成八片）二枚，茯苓三两，人参二两，白术四两，芍药三两。
以上五味药，用水八升，煮取三升药液，滤去药渣，每次温服一升，每日服用三次。
【方解】
少阴经是寒水之脏，所以寒邪伤人的重症，多传入少阴经，因此少阴一经，最多出现死证。方中以附子二枚为君药，取其药力锐利，且加重其重任；生用附子，一方面壮旺少阴的相火之阳，一方面驱散内外的寒邪，那么身体疼痛自然停止，恶寒自然消除，手足自然温暖了。以人参为臣药，用来巩固先天元气之本，使五脏六腑有根本，十二经脉有根源，脉象自然不沉，骨节得以调和。再辅以白术来培补脾土，芍药来平抑肝木，茯苓来渗泄水湿，水湿被渗泄则心火自然旺盛，火旺则阴翳消散，肝木平和则脾土更加安稳，土安则水有所制约，制约则生化有序，这确实是万全的治疗策略。那些因为畏惧而不敢使用此方，导致因循延误病情的，难道不可惜吗！
【注】
少阴病，表现为只想睡觉，脉象沉的，如果没有发热、口燥等热证，说明寒邪已经深入脏腑，不必迟疑，应立即用四逆汤温补，以消除阴寒、助长阳气。
【集注】
吴人驹说：脉沉需要辨别虚实，以及发病时间的长短。如果是患病多日且脉沉而有力的，需要从其他角度论述。
炙甘草二两，干姜一两半，附子（生用，去掉外皮，破成八片）一枚。
以上三味药，用水三升，煮取一升二合药液，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。
【方解】
方名“四逆”，主治少阴病内外皆寒，四肢厥冷逆乱。方中以甘草的甘温之性，温养阳气；以干姜、附子的辛温之性，助阳胜寒；甘草配合姜、附，能鼓动肾阳、温中散寒，具有在肾水中温暖脾土的功效；姜、附配合甘草，能通达关节、运行至四肢，具有驱逐阴寒、回阳救逆的力量，肾阳鼓动，寒阴消退，则阳气外达而脉象自升，手足自然温暖了。
【集解】
汪琥说：少阴病，本来的脉象是微细的，病人只想睡觉。现在轻取脉象，微脉不见，重取脉象，细脉几乎消失，脉象伏匿而至于沉，这是寒邪深入体内，快要进入脏腑了，温补不容许不紧急。稍微迟缓一点，就会出现恶寒身体蜷缩、呕吐腹泻、烦躁、无法躺卧睡眠、手足逆冷、脉搏摸不到等症状，各种死证就会立刻到来，四逆汤的使用可以稍微延缓吗？
【注】
少阴病只想睡觉，脉象微细，已经属于阳气被阴寒困阻的情况。再加上出现下利，恐怕阴气下降到了极点、阳气即将下脱。所以以葱白为君药，大通阳气使其上升；佐以干姜、附子，急胜阴寒使其缓降，那么尚未脱失的阳气就可以恢复了。
【集注】
方有执说：少阴病加上出现下利，不仅是在经络，也是脏腑寒甚、阴气极盛的表现。治疗用干姜、附子，是为了胜阴，阴胜则寒自散。用葱白而叫“白通”，是为了通阳，阳通则阴自消。
程知说：这里说的是下利应当通阳。少阴病，指的是有脉微细、想睡觉的症状。少阴病下利，是阴气极盛，恐怕导致格阳（真寒假热），所以用姜、附来消阴，用葱白来升阳。“通”的意思，一是温补，使阳气能够进入；一是发散，使阴气容易消散。
[Formula of Fuzi Decoction]
Fuzi (Aconiti Lateralis Radix Praeparata, peeled, raw, broken into eight pieces) 2 units; Fuling (Poria), 3 liang; Renshen (Ginseng Radix et Rhizoma), 2 liang; Baizhu (Atractylodis Macrocephalae Rhizoma), 4 liang; Shaoyao (Paeoniae Radix Alba), 3 liang.
The above five herbs are boiled in 8 sheng of water to obtain 3 sheng of decoction. The dregs are removed, and 1 sheng is taken warm, three times a day.
[Explanation of the Formula]
Shaoyin (Lesser Yin) is the zang-organ associated with cold water. Therefore, severe cases of cold pathogen invasion often enter the Shaoyin channel. Consequently, the Shaoyin channel sees the most fatal syndromes. In this formula, Fuzi (Aconiti Lateralis Radix Praeparata) serves as the sovereign drug (Jun Yao). Two units are used for their sharp potency and heavy responsibility. Used raw, it first strengthens the ministerial fire (Xiang Huo) yang of Shaoyin, and secondly disperses cold inside and outside the body. Thus, body pain stops naturally, aversion to cold is eliminated, and the hands and feet become warm. Renshen (Ginseng Radix et Rhizoma) serves as the minister drug (Chen Yao) to consolidate the root of vital qi, ensuring that the five zang organs and six fu organs have a foundation, and the twelve meridians have roots. The pulse will naturally not be deep, and the bone joints will harmonize. Furthermore, Baizhu (Atractylodis Macrocephalae Rhizoma) assists in cultivating earth (Spleen), Shaoyao (Paeoniae Radix Alba) pacifies wood (Liver), and Fuling (Poria) drains water. When water is drained, fire becomes prosperous; when fire is prosperous, yin shadows dissipate. When wood is pacified, earth is stabilized; when earth is stable, water is controlled. When controlled, transformation and generation proceed smoothly. This is indeed a perfect therapeutic strategy. It is truly regrettable if one dares not use it due to fear, leading to delay and error!
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In Shaoyin disease, if the pulse is deep, urgent warming is required; Sini Tang (Four Reversals Decoction) is indicated.
[Annotation]
In Shaoyin disease, characterized by an inclination to sleep and a deep pulse, if there are no signs of fever or dry mouth, the cold pathogen has entered the zang organs. One should not hesitate but urgently warm with Sini Tang (Four Reversals Decoction) to eliminate yin and assist yang.
[Collected Annotations]
Wu Renju stated: A deep pulse must be differentiated as deficiency or excess, considering the duration of the illness. If the condition has persisted for many days and the deep pulse is forceful, it requires discussion from another perspective.
Zhi Gancao (Prepared Licorice Root), 2 liang; Ganjiang (Dried Ginger), 1.5 liang; Fuzi (Aconiti Lateralis Radix Praeparata, raw, peeled, broken into eight pieces), 1 unit.
The above three herbs are boiled in 3 sheng of water to obtain 1.2 sheng of decoction. The dregs are removed, and the decoction is divided into two warm doses. For robust individuals, a large Fuzi (Aconiti Lateralis Radix Praeparata) of 1 unit and Ganjiang (Dried Ginger) of 3 liang may be used.
[Explanation of the Formula]
The name "Sini" (Four Reversals) indicates its treatment of Shaoyin disease where cold pervades both interior and exterior, resulting in cold extremities (Jue Ni). Gancao (Licorice Root) with its sweet and warm nature warms and nourishes yang as the sovereign drug. Ganjiang (Dried Ginger) and Fuzi (Aconiti Lateralis Radix Praeparata) with their acrid and warm nature assist yang to overcome cold as minister drugs. Gancao combined with Jiang and Fu drives kidney yang and warms the middle jiao to dispel cold, possessing the function of warming earth within water. Jiang and Fu combined with Gancao penetrate joints and travel to the four limbs, possessing the power to drive out yin and restore yang. As kidney yang is driven, cold yin dissipates, yang reaches the exterior, the pulse rises, and the hands and feet become warm.
[Collected Exegesis]
Wang Hu stated: Shaoyin disease originally presents with a faint and thin pulse and an inclination to sleep. Now, upon light palpation, the faint pulse is absent; upon heavy palpation, the thin pulse nearly vanishes, becoming hidden and sinking. This indicates the cold pathogen has deeply penetrated the interior, likely entering the zang organs. Warming cannot be delayed. If slightly delayed, symptoms such as aversion to cold, curled-up posture, vomiting, diarrhea, irritability, inability to lie down or sleep, cold extremities, and absence of pulse will arise, leading immediately to various fatal syndromes. Can the use of Sini Tang (Four Reversals Decoction) be delayed?
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In Shaoyin disease, if diarrhea occurs, Baitong Tang (White Penetration Decoction) is the primary treatment.
[Annotation]
Shaoyin disease, characterized by an inclination to sleep and a faint-thin pulse, already indicates yang being constrained by yin. The addition of diarrhea suggests that yin descent has reached its extreme, and yang is about to collapse downward. Therefore, Congbai (Allii Tuberosi Bulbus) is used as the sovereign drug to thoroughly unblock yang and promote its ascent. Ganjiang (Dried Ginger) and Fuzi (Aconiti Lateralis Radix Praeparata) are used as assistant drugs to urgently overcome yin and slow its descent, thereby restoring the yang that has not yet collapsed.
[Collected Annotations]
Fang Youzhi stated: Shaoyin disease accompanied by diarrhea indicates not only involvement of the channels but also severe cold in the zang organs and extreme abundance of yin. The use of Ganjiang (Dried Ginger) and Fuzi (Aconiti Lateralis Radix Praeparata) aims to overcome yin, so cold dissipates naturally. The use of Congbai (Allii Tuberosi Bulbus), named "Baitong," aims to unblock yang, so yin dissipates naturally when yang is unblocked.
Cheng Zhi stated: This passage discusses that diarrhea should be treated by unblocking yang. Shaoyin disease refers to the syndrome of faint-thin pulse and inclination to sleep. Shaoyin diarrhea represents extreme yin abundance, fearing the occurrence of Ge Yang (deflection of yang). Thus, Jiang and Fu are used to dissipate yin, and Congbai (Allii Tuberosi Bulbus) to raise yang. "Tong" (unblock) implies two functions: one to warm and allow yang to enter; the other to disperse and allow yin to scatter easily.
Wang Hu stated: Kidney deficiency without fire fails to govern water, causing diarrhea. Baitong Tang (White Penetration Decoction) is used to warm the interior and dispel cold.