青龙象肝木之两歧。而主两伤之疾。中风见寒脉。伤寒见风脉。则为荣卫之两伤。
故以青龙汤主之。伤寒表不解。则麻黄汤可以发。中风表不解。则桂枝汤可以散。
惟其表且不解。而又加之心下有水气。则非麻黄汤所能发。桂枝汤所能散。乃须
小青龙汤。始可祛除表里之邪气尔。麻黄味甘辛温。为发散之主。表不解。应发散
之。则以麻黄为君。桂味辛热。甘草味甘平。甘辛为阳。佐麻黄表散之。用二者所以
为臣。芍药味酸微寒。五味子味酸温。二者所以为佐者。寒饮伤肺。咳逆而喘。则肺
气逆。内经曰。肺欲收。急食酸以收之。故用芍药五味子为佐。以收逆气。干姜味辛
热。细辛味辛热。半夏味辛微温。三者所以为使者。心下有水。津液不行。则肾气燥。
内经曰。肾苦燥。急食辛以润之。是以干姜细辛半夏为使。以散寒水逆气。收寒水。
散津液。通行汗出而解矣。心下有水气散行。则所传不一。故又有增损之证。若渴
者去半夏。加栝蒌根。水蓄则津液不行。气燥而渴。半夏味辛温。燥津液者也。去之
则津液易复。栝蒌根味苦微寒。润枯燥者也。加之则津液通行。是为渴所宜也。若
微利去麻黄。加芫花。水气下行。渍入肠间。则为利。下利者不可攻其表。汗出必胀
满。麻黄专为表散。非下利所宜。故去之。芫花味苦寒。酸苦为涌泄之剂。水去利则
止。芫花下水。故加之。若噎者去麻黄。加附子。经曰。水得寒气冷必相搏。其人即溏。
又曰。病患有寒。复发汗。胃中冷。必吐蛔。噎为胃气虚竭。麻黄发汗。非胃虚冷所宜。
故去之。附子辛热。热则温其气。辛则散其寒。而噎者为当。两相佐之。是以祛散冷
寒之气。若小便不利。少腹满。去麻黄。加茯苓。水蓄在下焦不行。为小便不利。少腹
满。凡邪客于体者。在外者可汗之。在内者下之。在上者可涌之。在下者可泄之。水
蓄下焦。渗泄可也。发汗则非所当。故去麻黄。而茯苓味甘淡。专行津液。内经曰。热
淫于内。以淡渗之。渗溺行水。甘淡为所宜。故加茯蓄。若喘者去麻黄。加杏仁。喘为
气逆。麻黄发阳。去之则气易顺。杏仁味甘苦温。加之以泄逆气。金匮要略曰。其形
肿者。故不内麻黄。乃内杏子。以麻黄发其阳。故喘逆形肿。标本之疾。加减所同。盖
其类矣。
麻黄（君三两去节） 甘草（臣三两炙） 桂枝（臣三两去皮） 芍药（佐三两）
五味子（佐半升） 北细辛（佐三两） 干姜（使三两） 半夏（使半升洗）
上八味。以水一斗。先煮麻黄。减二升。去上沫。内诸药。煮取三升。去渣。温服一升。
The naming imagery of Qinglong Tang (Blue Dragon Decoction) derives from the bifurcated nature of Liver Wood Qi. It treats diseases caused by simultaneous injury from Wind and Cold pathogens. If a Zhongfeng (Wind Strike) syndrome presents with a Shanghan (Cold Damage) pulse, or if a Shanghan syndrome presents with a Zhongfeng pulse, this constitutes a dual injury to Ying (Nutritive) and Wei (Defensive) Qi.
Therefore, Qinglong Tang should be used as the primary treatment. If Shanghan causes the exterior syndrome to remain unresolved, Mahuang Tang (Ephedra Decoction) can be used to induce sweating; if Zhongfeng causes the exterior syndrome to remain unresolved, Guizhi Tang (Cinnamon Twig Decoction) can be used to dissipate the pathogen. However, if the exterior syndrome remains unresolved and is additionally complicated by Water-Qi stagnation in the epigastrium (center below the heart), neither Mahuang Tang nor Guizhi Tang can effectively resolve it. Only Xiao Qinglong Tang (Minor Blue Dragon Decoction) can dispel the pathogenic factors both at the exterior and within.
Mahuang (Ephedrae Herba) is sweet, acrid, and warm; it serves as the chief agent for dispersion. Since the exterior is unresolved and requires dispersion, Mahuang is employed as the Jun (Sovereign) herb. Guizhi (Cinnamomi Ramulus) is acrid and hot; Gancao (Glycyrrhizae Radix et Rhizoma) is sweet and neutral. Sweet and acrid flavors belong to Yang; they assist Mahuang in dispersing the exterior pathogen, serving as the Chen (Minister) herbs. Shaoyao (Paeoniae Radix Alba) is sour and slightly cold; Wuweizi (Schisandrae Fructus) is sour and warm. These two serve as the Zuo (Assistant) herbs because Cold-Fluid damages the Lung, causing cough, counterflow, and wheezing, leading to rebellious Lung Qi. The *Neijing* states: "The Lung desires consolidation; urgently consume sour substances to consolidate it." Thus, Shaoyao and Wuweizi are used as assistants to consolidate the rebellious Qi. Ganjiang (Zingiberis Rhizoma) is acrid and hot; Xixin (Asari Radix et Rhizoma) is acrid and hot; Banxia (Pinelliae Rhizoma) is acrid and slightly warm. These three serve as the Shi (Envoy) herbs because Water-Qi in the epigastrium impedes the flow of Body Fluids, leading to dryness of Kidney Qi. The *Neijing* states: "The Kidney dislikes dryness; urgently consume acrid substances to moisten it." Therefore, Ganjiang, Xixin, and Banxia are used as envoys to scatter the rebellious Qi of Cold-Water, consolidate Cold-Water, disperse Body Fluids, and allow the disease to resolve through the passage of sweat.
Once the Water-Qi in the epigastrium dissipates, the transmission varies, leading to modified syndromes. If there is thirst, remove Banxia and add Gualougen (Trichosanthis Radix). Water accumulation impedes Body Fluid flow, causing Qi dryness and thirst. Banxia is acrid and warm and dries Body Fluids; removing it allows Body Fluids to recover easily. Gualougen is bitter and slightly cold and moistens dryness; adding it allows Body Fluids to circulate, making it suitable for thirst. If there is slight diarrhea, remove Mahuang and add Yuanhua (Genkwa Flos). Water-Qi descends and infiltrates the intestines, causing diarrhea. For patients with diarrhea, the exterior should not be attacked; inducing sweat will inevitably cause abdominal fullness. Mahuang is specifically for exterior dispersion and is unsuitable for diarrhea; thus, it is removed. Yuanhua is bitter and cold; sour and bitter flavors act as emetic and purgative agents. When water is eliminated and diarrhea stops, Yuanhua drains water, so it is added. If there is a sensation of choking (Ye), remove Mahuang and add Fuzi (Aconiti Lateralis Radix Praeparata). The classics state: "When Water encounters Cold Qi, they contend, and the person becomes loose-stooled." It also states: "If a patient with Cold pathology undergoes sweating again, the Stomach becomes cold, and roundworms will be vomited." Choking results from deficiency and exhaustion of Stomach Qi. Mahuang induces sweating and is unsuitable for deficient-cold Stomach conditions; thus, it is removed. Fuzi is acrid and hot; heat warms the Qi, and acridity scatters Cold. This is appropriate for choking. The two complement each other to dispel Cold-Pathogenic Qi. If there is difficulty urinating and lower abdominal fullness, remove Mahuang and add Fuling (Poria). Water accumulation in the Lower Jiao fails to circulate, causing difficulty urinating and lower abdominal fullness. Generally, when pathogens reside in the body, those at the exterior are treated with sweating, those at the interior with purging, those above with emesis, and those below with draining/diuresis. Water accumulating in the Lower Jiao is suitable for draining/diuresis; sweating is inappropriate. Thus, Mahuang is removed. Fuling is sweet and bland and specifically promotes fluid circulation. The *Neijing* states: "For excessive Heat internally, use bland substances to drain them." Bland substances promote urination and move water; sweet and bland flavors are suitable. Thus, Fuling is added. (Note: The original text says "Fu Chu" which is likely a typo for Fuling in this context, translated here as Fuling based on standard formula modifications). If there is wheezing, remove Mahuang and add Xingren (Armeniacae Semen Amarum). Wheezing is due to rebellious Qi; Mahuang disperses Yang Qi, so removing it allows Qi to descend smoothly. Xingren is sweet, bitter, and warm; it is added to drain rebellious Qi. The *Jin Gui Yao Lue* states: "For those with edema, Mahuang is not included; instead, Xingzi (Apricot Seed) is used." Because Mahuang disperses Yang Qi, wheezing accompanied by physical swelling involves both root and branch pathologies, and the principles of addition and removal are similar as they share the same pathological category.
Mahuang (Jun, 3 liang, nodes removed) Gancao (Chen, 3 liang, honey-fried) Guizhi (Chen, 3 liang, bark removed) Shaoyao (Zuo, 3 liang)
Wuweizi (Zuo, 0.5 sheng) Beixixin (Zuo, 3 liang) Ganjiang (Shi, 3 liang) Banxia (Shi, 0.5 sheng, washed)
Take these eight ingredients. Add one dou of water. First decoct Mahuang, reducing the volume by two sheng. Remove the foam on the surface. Add the remaining herbs. Decoct until three sheng remain. Strain the dregs. Take one sheng, warmed.