治伤寒少阴证，始得之，反发热，脉沉者（少阴证，脉微细，但欲寐是也。太阳膀胱，
与
非两
麻黄 细辛（二两） 附子（一枚。炮。）先煮麻黄，去沫，内诸药煎。
此足少阴药也。太阳证发热，脉当浮，今反沉；少阴证脉沉，当无热，今发热，故曰反
也。热为邪在表，当汗；脉沉属阴，又当温。故以附子温少阴之经，以麻黄散太阳之寒而发
汗，以细辛肾经表药，联属其间，是汗剂之重者（赵嗣真曰∶仲景太阳篇云∶病发热头痛，
脉反沉，身体疼痛，当救其里，宜四逆汤；少阴病，始得之，反发热，脉沉者，麻黄附子细
辛汤；均是发热脉沉，以其头痛，故属太阳阳证，脉当浮而反不能浮者，以里久虚寒，正气
衰微，又身体疼痛，故宜救里，使正气内强，逼邪外出，而干姜、附子，亦能出汗而散；假
令里不虚寒而脉浮，则正属太阳麻黄证矣。均是脉沉为热，以无头痛，故名少阴病。阴病当
无热。今反热，寒邪在表，未全传里，但皮肤郁闭发热，故用麻黄、细辛以发表，熟附子以
温少阴之经，假使寒邪入里，外必无热，当见吐利厥逆等证，而正属少阴四逆汤证矣。由此
观之，表邪浮浅，发热之反犹轻；正气衰微，脉沉之反为重；此四逆汤不为不重于麻黄附子
细辛汤矣。又可见熟附配麻黄，发中有补，生附配干姜，补中有发，仲景之旨微矣。按∶伤
寒传入三阴，尚有在经表证，如太阴有桂枝加芍药汤，少阴有麻黄附子细辛汤，厥阴有当归
四逆汤之类，皆阴经表药也。又按∶少阴虽有反热而无头痛，厥阴虽有头痛而无身热，且痛
不如阳经之甚，若身热头痛全者，则属阳证。《医贯》曰∶有头痛连脑者，此系少阴伤寒，
宜麻黄附子细辛汤，不可不知。喻嘉言曰∶仲景太阳经但有桂枝加附子法，并无麻黄加附子
法，太阳无脉微恶寒之证，不当用附子，若见脉微恶寒、吐利、烦躁等证，则亡阳已在顷刻，
又不
俾外
不至
故
本方去细辛，加甘草，名麻黄附子甘草汤（仲景）∶治少阴病得之二三日，无证者，当
微发汗（得之二三日，较初得之为缓；无证，无吐利厥逆里证也；用此汤微发汗以散之，是
汗剂之轻者。周扬俊曰∶言无里证，则亦有反发热之表在可知也，二方皆治少阴表证，少阴
无发汗之法，汗之必至亡阳，惟此二证用之。《金匮》用本方治少阴水证，少气、脉沉、虚
胀）。
治疗伤寒少阴病，初起时，反而出现发热，脉象沉的证候（少阴病的特征是：脉微细，只想睡觉）。
麻黄二两、细辛二两、附子一枚（炮制）。先煮麻黄，去掉浮沫，再加入其他药物煎煮。
这是足少阴肾经的药物。太阳病发热，脉象应当浮，现在反而沉；少阴病脉象沉，应当没有热，现在反而发热，所以称为“反”。热邪在表，应当发汗；脉沉属于阴，又应当温补。所以用附子温补少阴经脉，用麻黄发散太阳寒邪并发汗，用细辛作为入肾经的解表药，连接二者之间，这是发汗剂中较重的一种。（赵嗣真说：张仲景在《伤寒论》太阳篇中说：病人发热头痛，脉象反而沉，身体疼痛，应当先救里，宜用四逆汤；少阴病，初起时，反而发热，脉象沉，用麻黄附子细辛汤；同样是发热且脉沉，因为伴有头痛，所以属于太阳阳证，脉象应当浮却反而不浮，是因为体内久有虚寒，正气衰微，加上身体疼痛，所以适宜救里，使正气内部强盛，逼迫邪气外出，而干姜、附子也能出汗散邪；假如体内不虚寒而脉象浮，那就正属于太阳麻黄汤证了。同样是脉沉且有热，因为没有头痛，所以命名为少阴病。阴病应当无热。现在反而发热，是寒邪在表，尚未完全传入里，只是皮肤郁闭导致发热，所以用麻黄、细辛来发表，熟附子来温补少阴经脉；假如寒邪进入体内，外部必然没有热，应当出现呕吐、腹泻、四肢厥冷等证候，那就正属于少阴四逆汤证了。由此看来，表邪浮浅，发热的“反”尚且较轻；正气衰微，脉沉的“反”则较重；这样看来，四逆汤的重要性并不亚于麻黄附子细辛汤。又可以看出，熟附子配伍麻黄，发汗中有补益作用，生附子配伍干姜，补益中有发散作用，张仲景的宗旨非常精微。按：伤寒传入三阴经，仍有在经表的证候，如太阴病有桂枝加芍药汤，少阴病有麻黄附子细辛汤，厥阴病有当归四逆汤之类，都是阴经的解表药。又按：少阴病虽然有反常发热但没有头痛，厥阴病虽然有头痛但没有身热，而且疼痛不如阳经剧烈，如果身热和头痛都具备，那就属于阳证。《医贯》说：有头痛连及脑部的，这属于少阴伤寒，宜用麻黄附子细辛汤，不可不知道。喻嘉言说：张仲景太阳经只有桂枝加附子法，并没有麻黄加附子法，太阳病没有脉微恶寒的证候，不应当用附子，如果见到脉微恶寒、呕吐腹泻、烦躁等证候，那么亡阳就在顷刻之间，又不……因此本方去掉细辛，加入甘草，名为麻黄附子甘草汤（出自张仲景）：治疗少阴病得之二三日，没有严重里证的，应当轻微发汗（得之二三日，比初得病时较缓；无证，指没有呕吐、腹泻、四肢厥冷等里证；用此汤轻微发汗以疏散邪气，这是发汗剂中较轻的一种。周扬俊说：说没有里证，那么也有反常发热的表证存在可知，这两个方子都治疗少阴表证，少阴病一般没有发汗的方法，发汗必定导致亡阳，只有这两种证候可以使用。《金匮要略》用本方治疗少阴水证，表现为少气、脉沉、虚胀）。
Treats Shaoyin syndrome (Shaoyin Syndrome) in cold damage (Shanghan), where upon initial onset, there is fever (Fever) contrary to expectation, and the pulse (Pulse) is deep (Deep Pulse). (Shaoyin syndrome is characterized by a faint and fine pulse, and a desire to sleep.)
Ephedrae Herba (Mahuang, 麻黄) two liang; Asari Radix (Xixin, 细辛) two liang; Aconiti Lateralis Radix Praeparata (Fuzi, 附子) one piece (prepared). Boil Ephedrae Herba first, remove the foam, then add the other herbs and decoct.
This is a formula for the Foot-Shaoyin Kidney meridian. In Taiyang syndrome, fever should present with a floating pulse; here it is deep instead. In Shaoyin syndrome, a deep pulse should accompany no fever; here there is fever instead. Hence it is termed "contrary." Fever indicates pathogenic factors in the exterior, requiring sweating (Diaphoresis); a deep pulse belongs to Yin, requiring warming (Warming). Therefore, Aconiti Lateralis Radix Praeparata warms the Shaoyin meridians, Ephedrae Herba disperses Taiyang cold and induces sweating, and Asari Radix serves as an exterior-releasing herb entering the Kidney meridian, linking the two. This is a heavy sweating agent. (Zhao Sizhen stated: In the Taiyang chapter of Zhang Zhongjing's work, it says: If a patient has fever, headache, and a deep pulse, along with body pain, one should first rescue the interior, using Sini Tang (Four Reversal Decoction). For Shaoyin disease, if upon initial onset there is contrary fever and a deep pulse, Mahuang Fuzi Xixin Tang (Ephedra, Aconite, and Asari Decoction) is used. Both present with fever and a deep pulse. Because headache is present, it belongs to Taiyang Yang syndrome; the pulse should be floating but is not, due to chronic interior deficiency-cold and decline of healthy Qi. With body pain, rescuing the interior is appropriate to strengthen internal healthy Qi, forcing pathogens out; Ganjiang (Dried Ginger) and Fuzi can also induce sweating to disperse pathogens. If the interior is not deficient-cold and the pulse is floating, it strictly belongs to the Taiyang Mahuang syndrome. Both present with deep pulse and heat, but without headache, hence named Shaoyin disease. Yin diseases should have no fever. The current fever indicates cold pathogens in the exterior, not yet fully transmitted to the interior, but causing skin constriction and fever. Thus, Mahuang and Xixin are used to release the exterior, and Shu Fuzi (Prepared Aconite) to warm the Shaoyin meridians. If cold pathogens enter the interior, there will likely be no external fever, but symptoms such as vomiting, diarrhea, and cold limbs would appear, strictly belonging to the Shaoyin Sini Tang syndrome. From this, we see that superficial exterior pathogens with contrary fever are lighter; decline of healthy Qi with a deep pulse is heavier. Thus, Sini Tang is not less important than Mahuang Fuzi Xixin Tang. Furthermore, Shu Fuzi combined with Mahuang provides tonification within dispersion, while Sheng Fuzi (Raw Aconite) combined with Ganjiang provides dispersion within tonification. Zhang Zhongjing's principles are subtle. Note: When cold damage transmits to the Three Yin meridians, exterior syndromes on the meridians may still exist, such as Guizhi Jia Shaoyao Tang (Cinnamon Twig plus Peony Decoction) for Taiyin, Mahuang Fuzi Xixin Tang for Shaoyin, and Danggui Sini Tang (Angelica Sinensis and Cinnamon Twig Decoction) for Jueyin; these are all exterior-releasing herbs for Yin meridians. Also note: Shaoyin may have contrary fever but no headache; Jueyin may have headache but no body heat, and the pain is less severe than in Yang meridians. If both body heat and headache are present, it belongs to Yang syndrome. *Yi Guan* states: Headache extending to the brain belongs to Shaoyin cold damage, treated with Mahuang Fuzi Xixin Tang; this must be known. Yu Jiayan stated: Zhang Zhongjing's Taiyang meridian only has Guizhi Jia Fuzi method, not Mahuang Jia Fuzi method. Taiyang does not present with faint pulse and aversion to cold, so Fuzi should not be used. If faint pulse, aversion to cold, vomiting, diarrhea, and irritability are seen, Yang collapse is imminent, and... Therefore, removing Xixin and adding Gancao (Licorice Root) from this formula creates Mahuang Fuzi Gancao Tang (Ephedra, Aconite, and Licorice Decoction) (from Zhang Zhongjing): It treats Shaoyin disease occurring for two or three days without severe interior symptoms, requiring mild diaphoresis (Two or three days is slower than initial onset; 'no symptoms' refers to absence of vomiting, diarrhea, and cold limbs/interior symptoms; this formula mildly induces sweating to disperse pathogens, making it a light sweating agent. Zhou Yangjun stated: Stating 'no interior symptoms' implies the existence of contrary fever and exterior syndrome. Both formulas treat Shaoyin exterior syndromes. Shaoyin generally lacks methods for sweating; sweating leads to Yang collapse. Only these two syndromes permit their use. *Jingui Yaolue* uses this formula to treat Shaoyin water syndromes, presenting with shortness of breath, deep pulse, and distension).