本草有曰。轻可去实。即麻黄葛根之属是也。实为寒邪在表。皮腠坚实。荣卫胜。津
液内固之表实。非腹满便难之内实也。圣济经曰。汗不出而腠密。邪气胜而中蕴。
轻剂所以扬之。即麻黄葛根之轻剂耳。麻黄味甘苦。用以为君者。以麻黄为轻剂。
而专主发散。是以为君也。桂枝为臣者。以风邪在表又缓。而肤理疏者。则必以桂
枝解其肌。是用桂枝为臣。寒邪在经。表实而腠密者。则非桂枝所能独散。必专麻
黄以发汗。是当麻黄为主。故麻黄为君。而桂枝所以为臣也。内经曰。寒淫于内。治
以甘热。佐以辛苦者。是兹类欤。甘草味甘平。杏仁味甘苦温。用以为佐使者。内经
曰。肝苦急。急食甘以缓之。肝者荣之主也。伤寒荣胜卫固。血脉不利。是专味甘之
物以缓之。故以甘草杏仁为之佐使。且桂枝汤主中风。风则伤卫。风邪并于卫。则
卫实而荣弱。仲景所谓汗出恶风者。此为荣弱卫强者是矣。故桂枝汤佐以芍药。
用和荣也。麻黄汤主伤寒。寒则伤荣。寒邪并于荣。则荣实而卫虚。内经所谓气之
所并为血虚。血之所并为气虚者是矣。故麻黄佐以杏仁。用利气也。若是之论。实
处方之妙理。制剂之渊微。该通君子。熟明察之。乃见功焉。
麻黄（君三两去节） 桂枝（臣二两去皮） 甘草（佐使二两炙） 杏仁（佐使七十枚去皮尖）
上四味。以水九升。先煮麻黄。减二升。去上沫。内诸药。煮取二升半。去渣。温服八
合。缓取微汗。并不须啜粥。余如桂枝法将息。
本草中有记载：“轻清之品可以祛除表实”，指的就是麻黄、葛根这一类药物。所谓“实”，是指寒邪侵袭体表，导致皮肤腠理致密坚实，营卫之气亢盛，津液内守而形成的表实证，并非指腹部胀满、大便困难的里实证。《圣济经》说：“汗不出且腠理致密，邪气亢盛而郁结于中，需用轻扬之剂来宣散”，指的正是麻黄、葛根这类轻剂。
麻黄味甘、苦，作为君药使用，是因为麻黄属于轻剂，专门主司发散，所以被定为君药。桂枝作为臣药，是因为风邪在表时病情较缓，且肌肤纹理疏松者，必须用桂枝来解除肌表之邪，因此用桂枝为臣。当寒邪侵袭经脉，表现为表实且腠理致密时，单靠桂枝无法独自发散，必须专用麻黄来发汗，此时应以麻黄为主，所以麻黄为君，而桂枝为臣。《内经》说：“寒邪淫溢于内，治疗应用甘热之品，辅以辛苦之味”，大概就是指这种情况吧。
甘草味甘平，杏仁味甘、苦、温，二者作为佐使药使用。《内经》说：“肝苦急，宜食甘味以缓和之”。肝是营血的主宰。伤寒病中，若营气胜而卫气固，导致血脉运行不利，就应专门使用甘味药物来缓和它，因此用甘草和杏仁作为佐使。
况且，桂枝汤主治中风证，风邪容易伤及卫气，风邪并入卫分，则卫气实而营气弱。张仲景所说的“汗出恶风”，就是营弱卫强的表现，所以桂枝汤中佐以芍药，用来调和营气。麻黄汤主治伤寒证，寒邪容易伤及营气，寒邪并入营分，则营气实而卫气虚。《内经》所说“气并则为血虚，血并则为气虚”即是此理，所以麻黄汤中佐以杏仁，用来利肺气。像这样的论述，确实是处方用药的妙理，制剂配伍的精微之处，只有通达的君子仔细审察，才能见到疗效。
麻黄（君药，三两，去节） 桂枝（臣药，二两，去皮） 甘草（佐使药，二两，炙） 杏仁（佐使药，七十枚，去皮尖）
以上四味药，用水九升，先煮麻黄，水量减少二升，撇去上浮的泡沫，再加入其他药物，煮取药液二升半，去渣滓。温服八合，微微出汗即可，不需要喝粥助汗。其余调养方法参照桂枝汤的法度。
The Materia Medica states: "Light and dispersing agents can eliminate exterior excess," referring to herbs such as Ephedrae Herba (Mahuang, 麻黄) and Puerariae Radix (Gegen, 葛根). The term "excess" here refers to an exterior excess condition caused by cold pathogenic factors invading the exterior, resulting in solid and dense skin and interstices, with vigorous Ying (Nutritive) and Wei (Defensive) qi, and internal retention of body fluids. This is distinct from interior excess characterized by abdominal fullness and difficult defecation. The *Shengji Jing* (Holy Relief Classic) states: "When sweat does not occur and the interstices are dense, and pathogenic factors are vigorous and internally constrained, light and ascending agents are used to disperse them." This refers precisely to the light agents like Mahuang and Gegen.
Ephedrae Herba (Mahuang, 麻黄) has a sweet and bitter taste. It is employed as the Sovereign herb because it belongs to the category of light agents and specializes in dispersing and releasing the exterior; hence, it serves as the Sovereign. Cinnamon Twig (Guizhi, 桂枝) serves as the Minister herb. When wind pathogenic factors are on the exterior and the condition is relatively mild, or when the muscle texture is loose, one must use Guizhi to resolve the muscle layer; thus, it is designated as the Minister. However, when cold pathogenic factors invade the meridians, presenting with exterior excess and dense interstices, Guizhi alone cannot disperse the pathogen. One must rely specifically on Mahuang to induce sweating. In such cases, Mahuang takes precedence. Therefore, Mahuang is the Sovereign, and Guizhi is the Minister. The *Neijing* (Inner Canon) states: "When cold invades excessively within, treat it with sweet and hot substances, assisted by acrid and bitter ones." This likely applies to this scenario.
Licorice Root (Gancao, 甘草) has a sweet and neutral taste, and Apricot Seed (Xingren, 杏仁) has a sweet, bitter, and warm taste. They are used as Assistant and Envoy herbs. The *Neijing* states: "When the Liver suffers from tension/spasm, eat sweet foods to relax it." The Liver is the master of Ying blood. In Shaoyin disease (referring to Cold Damage affecting Ying), if Ying qi is vigorous and Wei qi is fixed, leading to poor circulation of blood vessels, one should exclusively use sweet-tasting substances to relax the tension. Therefore, Gancao and Xingren are used as Assistants and Envoys.
Furthermore, Guizhi Tang (Cinnamon Twig Decoction) treats Wind Strike syndrome. Wind pathogenic factors tend to injure Wei qi. When wind pathogenic factors merge with Wei, Wei becomes excessive while Ying becomes deficient. Zhang Zhongjing's description of "sweating and aversion to wind" refers to this state of deficient Ying and excessive Wei. Hence, in Guizhi Tang, Paeonia Root (Shaoyao, 芍药) is added as an assistant to harmonize Ying qi. Mahuang Tang (Ephedra Decoction) treats Cold Damage syndrome. Cold pathogenic factors tend to injure Ying qi. When cold pathogenic factors merge with Ying, Ying becomes excessive while Wei becomes deficient. This corresponds to the *Neijing*'s statement: "Where Qi merges, Blood becomes deficient; where Blood merges, Qi becomes deficient." Therefore, in Mahuang Tang, Xingren is added as an assistant to promote the movement of Qi. Such discussions reveal the profound principles of prescription formulation and the subtle nuances of decoction preparation. Only those who are thorough and discerning can fully understand and achieve therapeutic success upon careful examination.
Ephedrae Herba (Mahuang, 麻黄) [Sovereign, 3 liang, nodes removed]
Cinnamon Twig (Guizhi, 桂枝) [Minister, 2 liang, bark removed]
Prepared Licorice Root (Zhi Gancao, 炙甘草) [Assistant/Envoy, 2 liang, honey-fried]
Apricot Seed (Xingren, 杏仁) [Assistant/Envoy, 70 seeds, skin and tips removed]
Take the above four ingredients. Add nine sheng of water. First, boil Mahuang until the volume reduces by two sheng. Remove the foam that rises to the surface. Then add the remaining herbs. Boil until two and a half sheng of liquid remains. Strain out the dregs. Take eight he of the decoction warm. Aim for a slight perspiration. There is no need to drink porridge to assist sweating. Rest and care instructions follow those of Guizhi Tang.