治伤寒表不解。心下有水气。干呕发热而渴。或咳。或利。或噎。或小便不利少
或喘。此方主之。
麻黄（三两） 芍药（三两） 细辛（三两） 干姜（三两） 甘草（三两） 桂枝（三
两
上八味。以水一斗。先煮麻黄减二升。去上沫。纳诸药。煮取三升。去滓。温服一升。
若微
去
仁半升。
歌曰 桂麻姜芍草辛三。夏味半升记要谙。表不解兮心下水。咳而发热句中探。（柯韵
伯云
渴或利。留于肠胃则小便不利而小腹因满矣。惟发热而咳是为水证。）
加减歌曰 若渴去夏取蒌根。三两加来功亦壮。微利去麻加荛花。（吴云。此味不常用。
以
除尿短小腹胀。若喘除麻加杏仁。须去皮尖半升量。
蔚按。此伤寒太阳之表不解而动其里水也。麻、桂从太阳以祛表邪。细辛入少阴而行里
水。干姜散胸前之满。半夏降上逆之气。合五味之酸。芍药之苦。取酸苦涌泄而下行。既欲
下行而仍用甘草以缓之者。令药性不暴。则药力周到。能入邪气水饮互结之处而攻之。凡无
形之邪气从肌表出。有形之水饮从水道出。而邪气水饮一并廓清矣。喻嘉言云。方名小青龙
者。取其翻波逐浪以归江海。不欲其兴云升天而为淫雨之意。若泥麻黄过散。减去不用。则
不成其为龙。将何恃以翻波逐浪乎。
Treats cases where the exterior syndrome of Shanghan (Cold Damage) is not resolved, and there is fluid retention in the epigastrium. Symptoms include dry retching, fever with thirst, or cough, or diarrhea, or a sensation of choking in the throat, or dysuria with scanty urine, or wheezing. This formula is indicated for these conditions.
Ephedrae Herba (Mahuang, 麻黄) [3 liang], Paeoniae Radix Alba (Baishao, 白芍) [3 liang], Asari Radix et Rhizoma (Xixin, 细辛) [3 liang], Zingiberis Rhizoma Recens (Ganjiang, 干姜) [3 liang], Glycyrrhizae Radix et Rhizoma (Gancao, 甘草) [3 liang], Cinnamomi Ramulus (Guizhi, 桂枝) [3 liang], Schisandrae Fructus (Wuweizi, 五味子) [0.5 sheng], Pinelliae Rhizoma Preparatum (Banxia, 半夏) [0.5 sheng].
Take the above eight herbs. Add one dou of water. First decoct Ephedrae Herba until the volume reduces by two sheng. Remove the foam on the surface. Then add the remaining herbs. Decoct until three sheng of liquid remain. Strain the dregs. Take one sheng warm.
If there is slight thirst, remove Pinelliae Rhizoma Preparatum and add Tetrastigma Caulis (Gualougen, 瓜蒌根/天花粉) half a sheng.
Song verse: Guizhi, Mahuang, Ganjiang, Baishao, Gancao, Xixin each three liang; Banxia half a sheng must be well memorized. Exterior not resolved, water under the heart; cough with fever, probe within the sentence. (Ke Yunbo states: If there is thirst or diarrhea, it indicates fluid retention in the intestines and stomach, leading to dysuria and lower abdominal fullness. Only when there is fever and cough is it truly a fluid syndrome.)
Modification song verse: If thirsty, remove Banxia, take Gualougen. Add three liang, efficacy is also strong. If slight diarrhea, remove Mahuang, add Wanghua (Wikstroemiae Caulis, 荛花). (Wu says: This herb is rarely used. It is employed to relieve short, scanty urination and lower abdominal distension.) If wheezing, remove Mahuang, add Apricot Kernel (Xingren, 杏仁). Must remove skin and tips, measure half a sheng.
Commentary by Wei (Chen Nianzu): This is when the exterior syndrome of the Taiyang meridian in Shanghan is unresolved, stirring up internal fluid retention. Mahuang and Guizhi dispel exterior pathogens from the Taiyang meridian; Xixin enters the Shaoyin meridian to circulate and resolve internal fluids; Ganjiang disperses fullness in the chest; Banxia descends rebellious qi. Combined with the sourness of Wuweizi and the bitterness of Baishao, they utilize the principle of "sour and bitter inducing downward discharge" to direct the action downward. While intending to direct downward, Gancao is still used to moderate the properties, ensuring the medicinal action is not too violent, so that its power can thoroughly reach the site where pathogenic factors and fluid retention are interlocked to attack them. Generally, formless pathogenic factors exit through the muscle layer, while formed fluid retention exits through the water passages, thereby clearing both pathogens and fluid retention simultaneously. Yu Jiayan said: The name "Xiao Qinglong Tang" (Minor Blue Dragon Decoction) implies turning waves and chasing waves to return to the rivers and seas, not wishing it to raise clouds and ascend to heaven to become excessive rain. If one rigidly believes Mahuang is too dispersing and removes it, it ceases to be a dragon; what reliance would there be to turn waves and chase waves?