附子（二枚去皮破八片） 茯苓（三两） 人参（二两） 白术（四两） 芍药（三两）
上五味。以水八升。煮取三升。去滓。温服一升。日三服。
成注云。辛以散之。附子之辛。以散寒。甘以缓之。茯苓人参白术之甘。以补阳。酸以收之。芍药之酸。以扶
阴。所以然者。偏阴偏阳。则为病。火欲实。水当平之。不欲偏胜也。○上七字甚晦。
内台方议曰。少阴之气。上通于舌下。若有病。则口燥舌干。今口中和者。是无热也。背为阳。阳虚阴盛。则
背恶寒也。经曰。无热恶寒者。发于阴也。当灸之。宜灸背俞。与附子汤服之。以附子为君温经散寒。茯苓为臣。
而泄水寒之气。以白术芍药为佐而益燥其中。以人参为使。而补其阳。以益其元气。散其阴邪也。
武陵陈氏曰。四逆诸方。皆有附子。于此独名附子汤。其义重在附子。他方皆附子一枚。此方两枚可见也。附
子之用不多。则其力岂能兼散表里之寒哉。二枚生用。生则辛烈善走不独温少阴之经。而又走卫气。以治背恶寒也。
邪之所凑其气必虚。参术茯苓。皆甘温益气。以补卫气之虚。辛热与温补相合。则气可益而邪可散矣。既用生附之
辛烈。而又用芍药者。以敛阴气。使卫中之邪。不遽全进于阴耳。
琥按上三注。成氏云芍药之酸以扶阴云云。其意甚晦。内台以芍药与白术。同为佐而益燥其中。其义于芍药未
确。惟陈注。实为晓畅。或疑芍药酸寒。恐非中寒所宜。然方中用附子二枚。则过于温发。不妨用芍药以少敛。但
不必三两之多耳。
琥又按最前条。少阴病始得之。反发热。此里寒正气与之相争。故以发热为表实。方用熟附子。合麻黄细辛。
以温散之。此条少阴病一二日。亦始得之。口中和。其背恶寒。此里寒而正气大虚。不能与邪相争。故不发热。及
表里皆虚也。故用生附配参苓白术。以温补而发之。方中用芍药者盖气虚。血必随之而亦虚。故用芍药以扶阴也。
或问背恶寒。焉知非太阳病。未发热之证。余答云。太阳病未发热之时。口中亦和。要其证。当通身恶寒。而
寒在皮表。今者。少阴病。但背恶寒。而寒在脊之里。如遇此候。问病患当自言之。况太阳病头项强痛。与少阴病
但欲寐迥别。无待辩也。
少阴病。身体痛。手足寒。骨节痛。脉沉者。附子汤主之。（此条亦少阴中寒。宜温补之证。成注云。少阴肾
水而主骨节。寒伤营。先着。肢体而后入骨节。今者身体痛。手足寒。骨节痛者。营气为寒所折而不行也。加之脉
沉。沉为在里。乃少阴脏虚受寒。故其所过之经。皆作痛也。与附子汤。以温经补虚散寒。○武陵陈氏云。太阳麻
黄证中之痛与此相同。但太阳则头痛发热。此无头痛发热。而手足寒为异也。愚以此身体痛。当是身体以前。连背
脊以内骨节痛。故其脉见沉。若浑身骨节痛。全是太阳表实热证。何敢用附子汤。作里虚寒证治邪。据上病用附子
汤者。以附子散少阴之真寒。参术得茯苓引用。补下焦元气。加芍药者。谓其能和营止痛也。或问和营止痛何以不
用当归。余答云。当归治中寒。非不胜于芍药。奈本方中既用生附子为君。其性辛热。过于走窜。使不用芍药敛而
和之。恐反耗其营气。而痛无收摄矣。古方配合之妙。难以言传。学人能神而明之。庶可以加减而无误矣。）
少阴病。下利。便脓血者。桃花汤主之。（此条乃少阴中寒。即成下利之证。下利便脓血。协热者多。今言少
阴病下利。必脉微细。但欲寐。而复下利也。下利日久。至便脓血。乃里寒而滑脱也。武陵陈氏云。少阴下利。是
少阴初病。即下利。并非传经之利。则是先利为寒。后便脓血。为滑脱明矣。与桃花汤者。固下而散寒也。）
附子（二枚，去皮，破成八片） 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。去渣。温服一升。每日三次服用。
成无己注解说：辛味能发散，附子的辛味，用来散寒；甘味能缓急，茯苓、人参、白术的甘味，用来补阳；酸味能收敛，芍药的酸味，用来扶阴。之所以这样，是因为偏于阴或偏于阳都会导致疾病。火气要充实，水气应当平抑它，不希望出现偏胜的情况。○上面七个字非常晦涩难懂。
《内台方议》议论说：少阴经的气，上通于舌下。如果有病，就会口燥舌干。现在口中平和湿润，说明没有热邪。背部属阳，阳气虚而阴气盛，就会出现背部怕冷。经文说：没有热象而怕冷的，属于阴证。应当用灸法治疗，适宜灸背部的俞穴，同时服用附子汤。以附子为君药来温经散寒，茯苓为臣药，来泄除水寒之气，以白术、芍药为佐药来增益中焦的燥性，以人参为使药，来补益阳气，从而益其元气，驱散阴邪。
武陵陈氏说：四逆汤等各方，都含有附子，唯独这里命名为附子汤，其意义重在附子。其他方剂都用附子一枚，此方用两枚，由此可见。附子的用量不多，它的力量怎么能兼散表里之寒呢？两枚生用，生附子辛烈善走，不仅温暖少阴经脉，而且运行卫气，用来治疗背部怕冷。邪气聚集的地方，正气必定虚弱。人参、白术、茯苓，都是甘温益气之品，用来补益卫气的虚弱。辛热与温补相结合，那么正气可益而邪气可散。既然用了生附子的辛烈，又使用芍药的原因，是为了收敛阴气，使卫分中的邪气，不迅速全部传入阴分。
琥按：上述三条注释，成氏说“芍药的酸味用来扶阴”等等，意思非常晦涩。《内台方议》认为芍药与白术同为佐药来增益中焦的燥性，其对芍药的理解并不确切。只有陈氏的注释，实在清晰晓畅。有人怀疑芍药性酸寒，恐怕不适合中寒证。然而方中用了两枚附子，则过于温散发越，不妨用芍药稍微收敛一下。只是不必用到三两那么多罢了。
琥又按：最前面的条文，少阴病刚开始得病时，反而发热，这是里寒的正气与邪气相争，所以把发热当作表实来看待，方中使用熟附子，配合麻黄、细辛，来温散之。这一条少阴病一二日，也是刚开始得病，口中平和，背部怕冷，这是里寒且正气大虚，不能与邪气相争，所以不发热，以及表里皆虚。所以用生附子配伍人参、茯苓、白术，来温补而发汗解表。方中使用芍药，大概是因为气虚，血必然随之也虚，所以用芍药来扶阴。
有人问：背部怕冷，怎么知道不是太阳病未发热时的证候？我回答说：太阳病在未发热的时候，口中也是平和的。但要考察其证候，应当是全身怕冷，且寒在皮表。现在是少阴病，只是背部怕冷，且寒在脊柱之内。遇到这种情况，询问病患自己会说出来。况且太阳病有头项强痛，与少阴病的但欲寐截然不同，无需辩论。
少阴病，身体痛，手足寒冷，骨节痛，脉沉的，用附子汤主治。（这一条也是少阴中寒，宜用温补的证候。成无己注解说：少阴肾水主司骨节，寒伤营气，先附着肢体而后进入骨节。现在是身体痛，手足寒，骨节痛，是营气被寒气遏制而不能运行。加上脉沉，沉脉主里，乃是少阴脏虚受寒，所以它所经过的经脉，都产生疼痛。给予附子汤，以温经补虚散寒。○武陵陈氏说：太阳病麻黄汤证中的疼痛与此相同，但太阳病有头痛发热，此证无头痛发热，而手足寒冷，这是不同之处。我认为这里的身体痛，应当是身体前部连及背部脊柱以内的骨节痛，所以脉象见沉。如果是浑身骨节痛，完全是太阳表实热证，怎敢用附子汤作为里虚寒证来治邪？根据上述病情使用附子汤，是因为附子能散少阴的真寒，人参、白术得到茯苓的引导，补益下焦元气，加芍药的原因是，认为它能调和营气止痛。有人问：调和营气止痛为什么不用当归？我回答说：当归治疗中寒，并不比芍药差，无奈本方中既用生附子为君药，其性辛热，过于走窜，如果不使用芍药来收敛调和它，恐怕反而耗损营气，而疼痛无法收摄。古方配合的妙处，难以言传。学医的人如果能神而明之，或许可以在加减用药时不出错。）
少阴病，下利，大便带脓血的，用桃花汤主治。（这一条是少阴中寒，即表现为下利的证候。下利便脓血，多伴有热象。现在说少阴病下利，必定脉微细，但欲寐，而又出现下利。下利日久，至大便带脓血，乃是里寒导致的滑脱不禁。武陵陈氏说：少阴下利，是少阴初病就下利，并非传经而来的下利，那么先是下利为寒，后来便脓血，显然是滑脱所致。给予桃花汤，是为了固涩止泻并散寒。）
Aconiti Lateralis Radix Praeparata (two pieces, peeled and broken into eight slices), Poria (three liang), Ginseng Radix et Rhizoma (two liang), Atractodis Rhizoma (four liang), Paeoniae Radix Alba (three liang).
The above five herbs. Boil with eight sheng of water. Decoct to obtain three sheng. Remove the dregs. Take one sheng warm. Three times daily.
Cheng Wuji commented: Acrid flavors can disperse; the acridity of Aconiti Lateralis Radix Praeparata (Fuzi, Prepared Lateral Root of Aconite) disperses cold. Sweet flavors can moderate; the sweetness of Poria (Fuling, Poria), Ginseng Radix et Rhizoma (Renshen, Ginseng), and Atractodis Rhizoma (Baizhu, Rhizoma Atractodis Macrocephalae) tonifies Yang. Sour flavors can astringe; the sourness of Paeoniae Radix Alba (Shaoyao, White Peony Root) supports Yin. The reason for this is that deviation towards Yin or Yang leads to disease. If Fire desires to be substantial, Water should level it; there should not be any excessive dominance. ○ The preceding seven characters are very obscure.
*Neitai Fangyi* discusses: The Qi of Shaoyin (Lesser Yin) connects upwards to under the tongue. If there is pathology, there will be dry mouth and tongue. Now that the mouth is harmonious (moist and normal), it indicates no Heat. The back belongs to Yang. When Yang is deficient and Yin is abundant, there is aversion to cold in the back. The Classic states: Aversion to cold without heat originates from Yin syndromes. Moxibustion should be applied, preferably to the Back-Shu points on the back, while administering Fuzi Decoction (Aconiti Lateralis Radix Praeparata Decoction). Aconiti Lateralis Radix Praeparata (Fuzi, Prepared Lateral Root of Aconite) serves as the Sovereign herb to warm the channels and disperse cold; Poria (Fuling, Poria) serves as the Minister herb to drain damp-cold Qi; Atractodis Rhizoma (Baizhu, Rhizoma Atractodis Macrocephalae) and Paeoniae Radix Alba (Shaoyao, White Peony Root) serve as Assistant herbs to enhance dryness in the middle jiao; Ginseng Radix et Rhizoma (Renshen, Ginseng) serves as the Guide herb to tonify Yang, thereby benefiting Yuan Qi and dispersing pathogenic Yin.
Chen of Wuling stated: Among the Si Ni Tang (Four Reversal Decoction) and other formulas, all contain Aconiti Lateralis Radix Praeparata (Fuzi, Prepared Lateral Root of Aconite), yet only here is it named Fuzi Decoction (Aconiti Lateralis Radix Praeparata Decoction), emphasizing the role of Aconiti Lateralis Radix Praeparata (Fuzi, Prepared Lateral Root of Aconite). Other formulas use one piece of Aconiti Lateralis Radix Praeparata (Fuzi, Prepared Lateral Root of Aconite); this formula uses two pieces, which demonstrates this point. If the dosage of Aconiti Lateralis Radix Praeparata (Fuzi, Prepared Lateral Root of Aconite) is not large, how can its strength simultaneously disperse exterior and interior cold? Two pieces used raw: raw Aconiti Lateralis Radix (Sheng Fuzi, Raw Lateral Root of Aconite) is acrid, pungent, and agile in movement. It not only warms the Shaoyin (Lesser Yin) channel but also moves Wei Qi (Defensive Qi) to treat aversion to cold in the back. Where pathogenic factors gather, Zheng Qi (Upright Qi) must be deficient. Ginseng Radix et Rhizoma (Renshen, Ginseng), Atractodis Rhizoma (Baizhu, Rhizoma Atractodis Macrocephalae), and Poria (Fuling, Poria) are sweet and warm, tonifying Qi, to supplement the deficiency of Wei Qi (Defensive Qi). Combining acrid-hot herbs with warm-tonifying herbs allows Qi to be benefited and pathogens to be dispersed. Since raw Aconiti Lateralis Radix (Sheng Fuzi, Raw Lateral Root of Aconite) with its acrid-pungency is used, why is Paeoniae Radix Alba (Shaoyao, White Peony Root) also used? To astringe Yin Qi, preventing pathogenic factors in the Wei Qi (Defensive Qi) layer from rapidly advancing into the Yin layer.
Hu notes: Regarding the above three commentaries, Cheng’s statement that “the sourness of Paeoniae Radix Alba (Shaoyao, White Peony Root) supports Yin” is very obscure. *Neitai Fangyi* considers Paeoniae Radix Alba (Shaoyao, White Peony Root) and Atractodis Rhizoma (Baizhu, Rhizoma Atractodis Macrocephalae) both as Assistant herbs to enhance dryness in the middle, which is not accurate regarding Paeoniae Radix Alba (Shaoyao, White Peony Root). Only Chen’s commentary is clear and understandable. Some doubt that Paeoniae Radix Alba (Shaoyao, White Peony Root) is sour and cold, deeming it unsuitable for Zhong Han (Cold Damage). However, since two pieces of Aconiti Lateralis Radix Praeparata (Fuzi, Prepared Lateral Root of Aconite) are used in the formula, the warming and dispersing action is excessive; it is acceptable to use Paeoniae Radix Alba (Shaoyao, White Peony Root) to slightly astringe. It is just unnecessary to use as much as three liang.
Hu further notes: In the earliest clause, when Shao Yin Bing (Shaoyin Disease) is first contracted, fever appears contrary to expectation. This is because the internal Cold Zheng Qi (Upright Qi) struggles with the pathogen, so the fever is treated as an Exterior Excess pattern. The formula uses cooked Aconiti Lateralis Radix (Shu Fuzi, Cooked Lateral Root of Aconite) combined with Ephedrae Herba (Mahuang, Herb of Ephedra) and Asari Radix et Rhizoma (Xixin, Rhizome and Root of Asarum) to warm and disperse. In this clause, Shao Yin Bing (Shaoyin Disease) for one or two days is also newly contracted. The mouth is harmonious, and there is aversion to cold in the back. This indicates internal Cold with significant deficiency of Zheng Qi (Upright Qi), unable to struggle with the pathogen, hence no fever, and both exterior and interior are deficient. Therefore, raw Aconiti Lateralis Radix (Sheng Fuzi, Raw Lateral Root of Aconite) is paired with Ginseng Radix et Rhizoma (Renshen, Ginseng), Poria (Fuling, Poria), and Atractodis Rhizoma (Baizhu, Rhizoma Atractodis Macrocephalae) to warm, tonify, and induce sweating. Paeoniae Radix Alba (Shaoyao, White Peony Root) is used in the formula likely because Qi deficiency leads to Blood deficiency as well; thus, Paeoniae Radix Alba (Shaoyao, White Peony Root) is used to support Yin.
Question: How do we know that aversion to cold in the back is not the syndrome of Taiyang (Greater Yin) disease before fever appears? Answer: During Taiyang (Greater Yin) disease before fever, the mouth is also harmonious. However, the syndrome involves whole-body aversion to cold, with cold located at the skin and surface. Here, in Shao Yin Bing (Shaoyin Disease), there is only aversion to cold in the back, with cold located inside the spine. Upon encountering this condition, asking the patient will reveal this. Moreover, Taiyang (Greater Yin) disease features stiffness and pain in the head and neck, which is distinctly different from the desire to sleep found in Shao Yin Bing (Shaoyin Disease); no debate is needed.
In Shao Yin Bing (Shaoyin Disease), if there is body pain, cold hands and feet, bone and joint pain, and a deep pulse, Fuzi Decoction (Aconiti Lateralis Radix Praeparata Decoction) is the primary treatment. (This clause also represents Shao Yin Zhong Han (Shaoyin Cold Damage), a syndrome suitable for warming and tonification. Cheng Wuji commented: The Kidney water of Shaoyin governs bones and joints. Cold damages Ying Qi (Nutritive Qi), first affecting the limbs and then entering the joints. Now, body pain, cold hands and feet, and bone/joint pain indicate that Ying Qi (Nutritive Qi) is obstructed by Cold and cannot circulate. Additionally, a deep pulse indicates interior location. This is Shaoyin Zang (Viscera) deficiency suffering from Cold, causing pain in the channels it passes through. Fuzi Decoction (Aconiti Lateralis Radix Praeparata Decoction) is given to warm the channels, tonify deficiency, and disperse cold. ○ Chen of Wuling said: The pain in Taiyang (Greater Yin) Ma Huang Tang (Ephedra Decoction) syndrome is similar to this, but Taiyang (Greater Yin) presents with headache and fever, whereas this syndrome lacks headache and fever but has cold hands and feet, which is the difference. I believe the "body pain" here refers to pain in the anterior body extending to the posterior back and spinal joints, hence the deep pulse. If the entire body and joints were painful, it would be purely a Taiyang (Greater Yin) exterior excess-heat syndrome; how could one dare to use Fuzi Decoction (Aconiti Lateralis Radix Praeparata Decoction) to treat pathogenic factors as an interior deficiency-cold syndrome? Based on the aforementioned pathology, Fuzi Decoction (Aconiti Lateralis Radix Praeparata Decoction) is used because Aconiti Lateralis Radix Praeparata (Fuzi, Prepared Lateral Root of Aconite) disperses the true Cold of Shaoyin (Lesser Yin). Ginseng Radix et Rhizoma (Renshen, Ginseng) and Atractodis Rhizoma (Baizhu, Rhizoma Atractodis Macrocephalae), guided by Poria (Fuling, Poria), tonify the Yuan Qi (Original Qi) of the Lower Jiao. Paeoniae Radix Alba (Shaoyao, White Peony Root) is added because it harmonizes Ying Qi (Nutritive Qi) and stops pain. Question: Why not use Angelicae Sinensis Radix (Danggui, Dong Quai) to harmonize Ying Qi (Nutritive Qi) and stop pain? Answer: Angelicae Sinensis Radix (Danggui, Dong Quai) is effective for Zhong Han (Cold Damage) and is not inferior to Paeoniae Radix Alba (Shaoyao, White Peony Root). However, since raw Aconiti Lateralis Radix (Sheng Fuzi, Raw Lateral Root of Aconite) is the Sovereign herb in this formula, its nature is acrid and hot, moving excessively. Without using Paeoniae Radix Alba (Shaoyao, White Peony Root) to astringe and harmonize it, there is a risk of consuming Ying Qi (Nutritive Qi) further, leaving the pain uncontrolled. The subtlety of ancient formula combinations is hard to convey in words. If practitioners can understand them spiritually and clearly, they may adjust prescriptions without error.)
In Shao Yin Bing (Shaoyin Disease), if there is diarrhea with pus and blood in the stool, Tao Hua Tang (Peach Blossom Decoction) is the primary treatment. (This clause represents Shao Yin Zhong Han (Shaoyin Cold Damage) manifesting as diarrhea. Diarrhea with pus and blood often involves Heat. Now, stating Shao Yin Bing (Shaoyin Disease) with diarrhea implies a faint and thin pulse, desire to sleep, accompanied by diarrhea. Prolonged diarrhea leading to pus and blood in the stool indicates interior Cold causing slipping and incontinence. Chen of Wuling said: Shao Yin diarrhea occurs early in Shao Yin disease, not transmitted via meridians. Thus, initial diarrhea is due to Cold, and subsequent pus and blood in stool clearly indicate slipping/incontinence. Tao Hua Tang (Peach Blossom Decoction) is given to secure the lower jiao and disperse Cold.)