麻黄（去节，二两） 细辛（二两） 附子（一枚，炮去皮破八片） 上三味，以水一斗，先煮麻黄，减二升，去
上沫，纳诸药，煮取三升，去渣，温服一升，日三服。
少阴病，始得之，反发热，脉沉者，麻黄附子细辛汤主之。少阴病三字，所该者广，必从少阴诸现症，
细细详审，然后反发热，知为少阴之发热，否则何以知其非太阳阳明之发热耶？又必候其脉象之沉，然后
益知其为少阴无疑也，凡审症皆当如此。
附子、细辛，为少阴温经之药，夫人知之。用麻黄者，以其发热，则邪犹连太阳，未尽入阴，犹可引之
外达。不用桂枝而用麻黄者，盖桂枝表里通用，亦能温里，故阴经诸药皆用之，麻黄则专于发表。今欲散少
阴始入之邪，非麻黄不可，况已有附子足以温少阴之经矣。
麻黄（去节，二两） 甘草（二两，炙） 附子（一枚，炮去皮破八片） 上三味，以水七升，先煮麻黄一、两沸，
此当少煮。去上沫，纳诸药，煮取三升，去渣，温服一升，日三服。
少阴病，得之二、三日，麻黄附子甘草汤，微发汗，以二、三日无里症，故微发汗也。三阴经，惟少
阴与太阳为表里，而位最近，故犹有汗解之理。况二、
三日而无里症，则其邪未深入，此方较麻黄附子细辛少轻，以其无里症也。
Ephedrae Herba (Mahuang, 麻黄) [removed nodes, two liang] Asari Radix (Xixin, 细辛) [two liang] Aconiti Lateralis Radix Praeparata (Fuzi, 附子) [one piece, processed, peeled, broken into eight slices] The above three ingredients: take ten dou of water, first decoct Ephedrae Herba; when the volume reduces by two dou, remove the foam on the surface. Then add the remaining herbs, and decoct until three sheng of liquid remain. Strain off the dregs, and take one sheng warm, three times a day.
Shaoyin disease (disease pattern involving the Shaoyin channel), at its onset, presents with fever contrary to expectation, and a deep pulse. This is treated primarily with Mahuang Fuzi Xixin Tang (Cinnamon Twig, Aconite, and Asari Decoction). The term "Shaoyin disease" covers a broad scope; one must carefully examine all current symptoms specific to Shaoyin patterns before concluding that the "contrary fever" belongs to Shaoyin. Otherwise, how can one distinguish it from the fever of Taiyang or Yangming? Furthermore, only when the pulse is confirmed to be deep can one be certain it is undoubtedly Shaoyin. Such rigorous examination is required for all diagnostic assessments.
Aconiti Lateralis Radix Praeparata and Asari Radix are known as herbs that warm the channels in Shaoyin diseases. The reason for using Ephedrae Herba is that the presence of fever indicates the pathogenic factor still involves the Taiyang channel and has not fully entered the Yin level; thus, it can still be guided outward. Cinnamon Twig Decoction (Guizhi Tang) is used instead of Guizhi because Guizhi acts on both exterior and interior and can also warm the interior, making it suitable for various formulas involving Yin channels. In contrast, Ephedrae Herba specializes in releasing the exterior. To disperse the pathogenic factor newly entering Shaoyin, Ephedrae Herba is indispensable, especially since Fuzi is already present to sufficiently warm the Shaoyin channel.
Ephedrae Herba (Mahuang, 麻黄) [removed nodes, two liang] Glycyrrhizae Radix et Rhizoma (Gancao, 甘草) [two liang, honey-fried] Aconiti Lateralis Radix Praeparata (Fuzi, 附子) [one piece, processed, peeled, broken into eight slices] The above three ingredients: take seven sheng of water, first decoct Ephedrae Herba for one or two boils; it should be boiled slightly less here. Remove the foam on the surface, then add the remaining herbs, and decoct until three sheng of liquid remain. Strain off the dregs, and take one sheng warm, three times a day.
For Shaoyin disease presenting after two or three days, Mahuang Fuzi Gancao Tang (Cinnamon Twig, Aconite, and Licorice Decoction) is used to induce slight sweating. Since there are no interior syndromes after two or three days, slight sweating is appropriate. Among the Three Yin channels, only Shaoyin and Taiyang are exterior-interior pairs and are anatomically closest; therefore, resolution through sweating remains a valid therapeutic principle. Moreover, the absence of interior syndromes after two or three days indicates the pathogen has not deeply penetrated. Consequently, this formula is milder than Mahuang Fuzi Xixin Tang due to the lack of interior involvement.