青龙东方甲乙木神也。应春而主肝。专发主之令。为敷荣之主。万物出甲开甲。则
有两歧。肝有两叶。以应木叶。所以谓之青龙者。以发散荣卫两伤之邪。是应肝木。
之体耳。桂枝汤主中风。麻黄汤主伤寒。二者发散之纯者也。及乎大青龙汤则不
然。虽为发汗之剂。而所主又不一。必也中风脉浮紧。为中风见寒脉。是风寒两伤
也。伤寒脉浮缓。为伤寒见风脉。是风寒两伤也。风兼寒。寒兼风。乃大青龙汤专主
之也。见兹脉证。虽欲与桂枝汤解肌以祛风。而不能已其寒。则病不去。或欲以麻
黄汤发汗以散寒。而不能去其风。则病仍在。兹仲景所以特处大青龙汤。以两解
之。麻黄味甘温。桂枝味辛热。寒则伤荣。必以甘缓之。风则伤卫。必以辛散之。此风
寒两伤。荣卫俱病。故以甘辛相合。而为发散之剂。表虚肤缓者。则以桂枝为主。此
以表实腠理密。则以麻黄为主。是先麻黄后桂枝。兹麻黄为君。桂枝为臣也。甘草
味甘平。杏仁味甘苦。苦甘为助。佐麻黄以发表。大枣味甘温。生姜味辛。温辛甘相
合。佐桂枝以解肌。石膏味甘辛微寒。风阳邪也。寒阴邪也。风则伤阳。寒则伤阴。荣
卫阴阳。为风寒两伤。则非轻剂所能独散也。必须轻重之剂以同散之。乃得阴阳
之邪俱已。荣卫之气俱和。是以石膏为使。石膏为重剂。而又专达肌表者也。大青
龙汤。发汗之重剂也。非桂枝汤之所同。用之稍过。则又有亡阳之失。经曰。若脉微
弱。汗出恶风者。不可服。服之则厥逆。筋惕肉 。此为逆也。又曰。一服汗者停后服。
若复服。汗多亡阳。遂虚恶风。烦躁不得眠也。即此观之。剂之轻重可见矣。其用汤
者。宜详审之。
麻黄（君六两去节） 桂枝（臣二两去皮） 甘草（佐一两炙） 杏仁（佐四十枚去皮尖） 生姜（佐三两切） 大
枣（佐十枚擘） 石膏（使如鸡子大碎）
上七味。以水九升。先煮麻黄。减二升。去上沫。内诸药。煮取三升。去渣。温服一升。
取微似汗。汗出多者。温粉止之。一服汗者。停后服。若复服。汗多亡阳。遂虚（一作逆）恶风。烦躁不得眠也。
又温粉方
白术 本 川芎 白芷（各等分）
上捣罗为细末。每末一两。入米粉三两。和令匀。粉扑周身止汗。无 本亦得。
青龙是东方甲乙木的神灵，对应春季并主宰肝脏。它专门发布主管生长的命令，是敷布繁荣的主宰。万物从“甲”中生出、破壳而出时，往往会有两个分枝。肝脏有两叶，以对应木叶的形态。之所以称之为青龙，是因为它能发散营卫两伤的邪气，这正符合肝木的本体特性。桂枝汤主治中风证，麻黄汤主治伤寒证，这两者都是纯粹的解表发散方剂。至于大青龙汤则不然，虽然它也是发汗的药剂，但所主治的病证并不单一。必须是中风证出现浮紧的脉象，这是中风兼见寒邪的脉象，属于风寒两伤；或者是伤寒证出现浮缓的脉象，这是伤寒兼见风邪的脉象，也属于风寒两伤。风兼夹寒邪，寒兼夹风邪，正是大青龙汤专门主治的情况。见到这样的脉证，如果只用桂枝汤解肌祛风，却无法消除寒邪，那么病就不会好；如果只用麻黄汤发汗散寒，却无法去除风邪，那么病依然存在。这就是张仲景特意设立大青龙汤，以同时解除这两种邪气的原因。
麻黄味甘性温，桂枝味辛性热。寒邪会损伤营血，必须用甘味药来缓和它；风邪会损伤卫气，必须用辛味药来疏散它。这是风寒两伤、营卫俱病的缘故，所以将甘味与辛味药物相合，作为发散的方剂。对于表虚、皮肤松弛的患者，以桂枝为主药；而此处患者表实、腠理致密，所以以麻黄为主药。因此先使用麻黄，后使用桂枝，这里麻黄为君药，桂枝为臣药。甘草味甘性平，杏仁味甘苦，苦甘相合起到辅助作用，协助麻黄发表。大枣味甘性温，生姜味辛，温辛甘相合，协助桂枝解肌。石膏味甘辛微寒，风属于阳邪，寒属于阴邪。风邪伤阳，寒邪伤阴，营卫阴阳被风寒两伤，就不是轻剂所能单独驱散的。必须用轻重不同的药物共同发散，才能使阴阳之邪全部消除，营卫之气调和，因此用石膏为使药。石膏属于重剂，又专门直达肌表。大青龙汤是发汗的重剂，不同于桂枝汤。如果使用稍微过量，又会导致亡阳的过失。经文说：如果脉微弱，出汗且怕风的，不可服用。服用了就会出现四肢厥冷、筋惕肉的现象，这是误治。经文又说：服一次药如果出汗了，就停止后面的服药。如果再服用，汗出过多导致亡阳，进而虚弱、怕风、烦躁、无法入睡。由此看来，药剂的轻重程度就可以知道了。使用汤剂时，应当详细审察。
麻黄（君药六两，去节） 桂枝（臣药二两，去皮） 甘草（佐药一两，炙） 杏仁（佐药四十枚，去皮尖） 生姜（佐药三两，切） 大枣（佐药十枚，掰开） 石膏（使药如鸡蛋大小，捣碎）
以上七味药，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，煮取三升药液，去渣滓。温服一升，取微微似有汗出的效果。如果汗出过多，用温粉止汗。服一次药如果出汗了，就停止后面的服药。如果再服用，汗出过多导致亡阳，进而虚弱（一说为逆证）、怕风、烦躁、无法入睡。
Qinglong (Azure Dragon) is the spirit of Jia and Yi Wood in the East. It corresponds to Spring and governs the Liver. It exclusively issues the command of growth and is the master of spreading prosperity. When all things emerge from "Jia" (the first heavenly stem, symbolizing sprouting) and break open, they often have two branches. The liver has two lobes, corresponding to the shape of wood leaves. Therefore, it is called Qinglong because it can disperse pathogens that injure both Ying (Nutritive Qi) and Wei (Defensive Qi), which aligns with the nature of Liver Wood. Guizhi Tang (Cinnamon Twig Decoction) treats Zhongfeng (Wind Strike/Exterior Deficiency Syndrome), and Mahuang Tang (Ephedra Decoction) treats Shanghan (Cold Damage/Exterior Excess Syndrome); these two are pure exterior-dispersing formulas. However, Daqinglong Tang (Major Azure Dragon Decoction) is different. Although it is a sweating agent, its indications are not singular. It must be applied when a Zhongfeng syndrome presents with a floating and tight pulse, indicating Wind pathogen combined with Cold pathogen (Feng Han Liang Shang); or when a Shanghan syndrome presents with a floating and slow pulse, indicating Cold pathogen combined with Wind pathogen, also constituting Feng Han Liang Shang. Wind accompanied by Cold, and Cold accompanied by Wind, are precisely what Daqinglong Tang specializes in treating. Upon observing such pulses and symptoms, if one were to use only Guizhi Tang to release the muscle layer and dispel Wind, it could not eliminate the Cold, so the disease would not resolve. If one were to use only Mahuang Tang to induce sweating and scatter Cold, it could not remove the Wind, so the disease would remain. This is why Zhang Zhongjing specifically established Daqinglong Tang to resolve both simultaneously.
Mahuang (Ephedrae Herba) is sweet and warm; Guizhi (Cinnamomi Ramulus) is acrid and hot. Cold injures Ying (Nutritive Qi), so it must be moderated with sweet herbs. Wind injures Wei (Defensive Qi), so it must be dispersed with acrid herbs. This is because Wind and Cold have jointly injured, causing both Ying and Wei to be diseased. Therefore, sweet and acrid herbs are combined to form a dispersing agent. For patients with exterior deficiency and loose skin, Guizhi is the principal herb. Here, due to exterior excess and dense interstices (Couli), Mahuang is the principal herb. Thus, Mahuang is used first, followed by Guizhi; Mahuang serves as the Jun (Monarch) herb, and Guizhi as the Chen (Minister) herb. Gancao (Glycyrrhizae Radix et Rhizoma) is sweet and neutral; Xingren (Armeniacae Semen Amarum) is sweet and bitter. Bitter and sweet assist each other, helping Mahuang to release the exterior. Dazao (Ziziphi Jujubae Fructus) is sweet and warm; Shengjiang (Zingiberis Rhizoma Recens) is acrid. Warm, acrid, and sweet combine to help Guizhi release the muscle layer. Shigao (Gypsum Fibrosum) is sweet, acrid, and slightly cold. Wind is a Yang pathogen; Cold is a Yin pathogen. Wind injures Yang; Cold injures Yin. Since Ying, Wei, Yin, and Yang are injured by both Wind and Cold, light agents alone cannot disperse them. Heavy and light agents must be used together to disperse them, so that both Yin and Yang pathogens are eliminated, and Ying and Wei Qi are harmonized. Therefore, Shigao is used as the Shi (Envoy) herb. Shigao is a heavy agent and specifically reaches the muscle and surface. Daqinglong Tang is a heavy sweating agent, distinct from Guizhi Tang. If used excessively, it may lead to Wang Yang (Loss of Yang Qi). The Classic states: "If the pulse is faint and weak, with sweating and aversion to wind, do not administer it. If administered, it will cause Jue Ni (cold extremities) and Jin Ti Rou Tiao (twitching of tendons and muscles). This is an adverse reaction." It further states: "After one dose, if sweating occurs, stop taking the remaining medicine. If taken again, excessive sweating will lead to loss of Yang Qi, resulting in deficiency, aversion to wind, irritability, and inability to sleep." From this, the weightiness or lightness of the dosage can be seen. When using decoctions, one should examine carefully.
Mahuang (Jun, 6 liang, remove nodes) Guizhi (Chen, 2 liang, remove bark) Gancao (Zuo, 1 liang, honey-fried) Xingren (Zuo, 40 seeds, remove skin and tips) Shengjiang (Zuo, 3 liang, sliced) Dazao (Zuo, 10 seeds, split) Shigao (Shi, size of a chicken egg, crushed)
The above seven ingredients. Use 9 sheng of water. First boil Mahuang, reduce by 2 sheng, remove the foam on the surface. Add the remaining herbs. Boil until 3 sheng remains. Strain. Take 1 sheng warm. Aim for slight perspiration. If sweating is excessive, use Wen Fen (Warm Powder) to stop it. After one dose, if sweating occurs, stop subsequent doses. If taken again, excessive sweating leads to loss of Yang Qi, resulting in deficiency (or reversal), aversion to wind, irritability, and insomnia.
Additionally, the Wen Fen Formula:
Baizhu (Atractylodis Macrocephalae Rhizoma) Ben Cao (Ligustici Chuanxiong Rhizoma, here referring to Ligusticum sinense or similar aromatic root, often identified as Gaoben in context of external powder) Chuanxiong (Ligustici Chuanxiong Rhizoma) Baizhi (Angelicae Dahuricae Radix) (equal parts)
Grind and sieve into fine powder. For every 1 liang of powder, mix with 3 liang of rice flour evenly. Dust over the whole body to stop sweating. Absence of Ben Cao is acceptable.