太阳病头痛发热身疼腰痛骨节疼痛恶寒无汗而喘者麻黄汤主之
寒为阴邪营为阴气阴邪中人则阴分受之故伤营血血秉肝气其性疏泄寒闭营阴失其疏泄之权是以无汗寒愈闭而血愈泄
则外束卫气闭藏而为寒是营血被伤而卫气受病也故伤在营血而治在卫气麻黄汤甘草保其中气桂枝发其营郁麻黄泄其卫气
杏仁利其肺气降逆而止喘也孔窍一开而卫郁外达则伤寒愈矣 卫气为阳外行皮毛营血为阴内行经络肺藏气而主卫肝藏血
而司营肺金收敛肝木疏泄阴阳自然之性也肝性疏泄而营血之内守者肺气敛之也肺气收敛而卫阳之外发者肝气泄之也收敛
则无汗疏泄则有汗风伤卫气卫病而非营病也然卫被风敛则内闭营阴营气不通是以发热故以桂枝泄经热而达营郁气病而用
血药者以气伤而累血也寒伤营血营病而非卫病也然营为寒束则外闭卫阳卫阳不宣是以恶寒故以麻黄泄表寒而达卫郁血病
而用气药者以血伤而累气也桂枝泄其肝血麻黄泄其肺气营卫分属于肺肝而统司于太阳故太阳风寒之初治首以桂枝麻黄二
方为定法也
麻黄（三两去节） 桂枝（一两去皮） 甘草（一两炙） 杏仁（七十枚汤泡去皮尖及两仁者）
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覆取微似汗不须 饮余如桂枝法将息
太阳病，出现头痛、发热、身体疼痛、腰痛、骨节疼痛、恶寒、无汗且伴有气喘的症状，应当用麻黄汤来主治。
寒邪属于阴邪，营气属于阴气。阴邪侵袭人体，就会使阴分受到损伤。因此，寒邪伤及营血。血液禀受肝气的特性，其性质主疏泄。寒邪闭阻营阴，导致失去疏泄的功能，所以表现为无汗。寒邪越是闭阻，血液的郁滞就越严重，进而外束卫气，使其闭藏而表现出寒象。这是营血被伤害而卫气受病的表现。所以，病位在营血，但治疗重点在卫气。麻黄汤中用甘草来保护中气，用桂枝来发散营分的郁结，用麻黄来宣泄卫气的郁闭，用杏仁来疏通肺气，降逆气以止喘。一旦孔窍开通，卫气的郁结得以向外通达，伤寒也就痊愈了。
卫气属阳，行于体表的皮毛；营血属阴，行于体内的经络。肺脏藏气并主管卫气，肝脏藏血并主管营气。肺金具有收敛的特性，肝木具有疏泄的特性，这是阴阳自然的属性。肝性主疏泄，而营血的内守功能是由肺气来收敛的；肺气主收敛，而卫阳的外发功能是由肝气来疏泄的。收敛则无汗，疏泄则有汗。风邪伤害卫气，是卫气生病而非营气生病。然而，卫气被风邪收敛，导致内部闭阻营阴，营气运行不通畅，所以出现发热。因此用桂枝来发散经中的热邪并通达营分的郁结。气分生病而使用血药，是因为气受伤会连累到血。寒邪伤害营血，是营血生病而非卫气生病。然而，营血被寒邪束缚，导致外部闭阻卫阳，卫阳不能宣通，所以出现恶寒。因此用麻黄来发散表部的寒邪并通达卫分的郁结。血分生病而使用气药，是因为血受伤会连累到气。桂枝发散肝血之郁，麻黄发散肺气之郁。营气和卫气分别归属于肺和肝，但统摄于太阳经。所以在太阳经受风寒的初期治疗中，首先以桂枝汤和麻黄汤作为固定的法则。
麻黄（三两，去节） 桂枝（一两，去皮） 甘草（一两，炙） 杏仁（七十枚，热水浸泡，去皮尖及双仁者）
以上四味药，用水九升，先煮麻黄，减少二升水，去掉水面上的浮沫，加入其他药物，煮取二升半药液，去渣，温服八合。服药后覆盖衣被以取得微微似有汗出的效果，不需要像服用桂枝汤那样喝热粥来辅助发汗，其余调养方法参照桂枝汤的法度。
In Taiyang disease, characterized by headache, fever, body ache, lower back pain, joint pain, aversion to cold, anhidrosis (absence of sweating), and wheezing, Mahuang Tang (Ephedra Decoction) is the primary prescription.
Cold is a Yin pathogen, and Ying (Nutritive Qi/Blood) is Yin in nature. When Yin pathogens invade the human body, they affect the Yin aspects. Thus, Cold injures Ying and Blood. Blood inherits the nature of Liver Qi, which is characterized by free flow and discharge (Shuxie). When Cold obstructs Ying-Yin, it loses its function of free flow and discharge, resulting in anhidrosis. The more Cold obstructs, the more severe the stagnation of Blood becomes, subsequently binding Wei (Defensive Qi) externally and causing it to store, manifesting as Cold. This indicates that Ying-Blood is injured while Wei-Qi is diseased. Therefore, although the pathology lies in Ying-Blood, the treatment focuses on Wei-Qi. In Mahuang Tang, Gancao (Licorice Root) protects the Middle Qi; Guizhi (Cinnamon Twig) disperses the stagnation in Ying; Mahuang (Ephedra Herb) vents the stagnation of Wei-Qi; and Xingren (Apricot Seed) benefits Lung Qi, descends rebellious Qi, and stops wheezing. Once the orifices open and the stagnation of Wei-Qi reaches outward, the Cold damage is cured.
Wei-Qi belongs to Yang and circulates externally in the skin and hair; Ying-Blood belongs to Yin and circulates internally in the meridians. The Lung stores Qi and governs Wei-Qi; the Liver stores Blood and manages Ying-Qi. Metal of the Lung has the nature of convergence, while Wood of the Liver has the nature of free flow and discharge; these are the natural properties of Yin and Yang. The Liver's nature is free flow and discharge, but the internal retention of Ying-Blood is controlled by the converging action of Lung Qi. The Lung's nature is convergence, but the external emission of Wei-Yang is facilitated by the discharging action of Liver Qi. Convergence results in anhidrosis, while free flow and discharge result in sweating. Wind injures Wei-Qi, causing disease in Wei rather than Ying. However, when Wei is constrained by Wind, it internally closes off Ying-Yin, leading to obstruction of Ying-Qi circulation, thus causing fever. Therefore, Guizhi (Cinnamon Twig) is used to vent heat in the channels and reach the stagnation in Ying. When Qi is diseased, blood-invigorating herbs are used because Qi injury affects Blood. Cold injures Ying-Blood, causing disease in Ying rather than Wei. However, when Ying is bound by Cold, it externally closes off Wei-Yang, preventing the diffusion of Wei-Yang, thus causing aversion to cold. Therefore, Mahuang (Ephedra Herb) is used to vent exterior Cold and reach the stagnation in Wei. When Blood is diseased, Qi-regulating herbs are used because Blood injury affects Qi. Guizhi vents the stagnation of Liver Blood, and Mahuang vents the stagnation of Lung Qi. Ying and Wei are respectively governed by the Lung and Liver but are collectively managed by the Taiyang channel. Hence, in the initial treatment of Wind-Cold affecting the Taiyang channel, Guizhi Tang (Cinnamon Twig Decoction) and Mahuang Tang (Ephedra Decoction) are established as the fixed methods.
Mahuang (Ephedrae Herba, 3 liang, remove joints)
Guizhi (Cinnamomi Ramulus, 1 liang, remove bark)
Gancao (Glycyrrhizae Radix et Rhizoma, 1 liang, honey-fried)
Xingren (Armeniacae Semen Amarum, 70 seeds, soak in boiling water, remove skin and tips, discard double-kernel seeds)
Take the above four ingredients, add 9 sheng of water, first boil Mahuang until the volume reduces by 2 sheng, skim off the foam on the surface, then add the remaining herbs. Boil until 2.5 sheng remains, strain, and take 8 he of the decoction warm. After ingestion, cover with blankets to induce a slight sweat. There is no need to drink hot porridge as in the method for Guizhi Tang; other post-medication care should follow the instructions for Guizhi Tang.