伤寒表不解。心下有水气。干呕。发热而咳。或渴。或利。或噎。或小便不利。少腹满。或喘者。
小青龙汤主之。
表寒不解。而心下有水饮。饮寒相抟。逆于肺胃之间。为干呕发热而咳。乃伤寒之兼证也。
夫饮之为物。随气升降。无处不到。或壅于上。或积于中。或滞于下。各随其所之而为病。而其治
法。虽各有加减。要不出小青龙之一法。麻黄、桂枝。散外入之寒邪。半夏、细辛、干姜。消内积
之寒饮。芍药、五味。监麻、桂之性。且使表里之药。相就而不相格耳。
小青龙汤方
麻黄 桂枝 芍药 细辛 干姜 炙甘草（各三两） 五味 半夏（各半升）
上八味。以水一斗。先煮麻黄减二升。去上沫。内诸药。煮取三升。去滓。温服一升。
大青龙合麻、桂而加石膏。能发邪气除烦躁。小青龙无石膏。有半夏、干姜、芍药、细辛、
五味。能散寒邪行水饮。而通谓之青龙者。以其有发汗蠲饮之功。夫热闭于经。而不用石膏。汗为
热隔。宁有能发之者乎。饮伏于内。而不用姜、夏。寒与饮抟。宁有能散之者乎。其芍药、五味。
不特收逆气而安肺气。抑以制麻、桂、姜、辛之势。使不相惊而相就。以成内外协济之功耳。
加减法
若微利者。去麻黄。加芫花如鸡子大。熬令赤色。
微利者。水渍入胃也。下利者。不可攻其表。故去麻黄之发表。而加芫花之行水。
若渴者。去半夏。加栝蒌根三两。
渴者。津液不足。故去半夏之辛燥。而加栝蒌之苦润。若饮结不布而渴者。似宜仍以半夏流湿
而润燥也。
若噎者。去麻黄。加附子一枚。炮。
噎者。寒饮积中也。附子温能散寒。辛能破饮。故加之。麻黄发阳气。增胃冷。故去之。
若小便不利。小腹满。去麻黄。加茯苓四两。
小便不利。小腹满。水蓄于下也。故加茯苓以泄蓄水。不用麻黄。恐其引气上行。致水不下也。
若喘者。去麻黄。加杏仁半升。去皮尖。
喘者。水气在肺。故加杏仁下气泄肺。麻黄亦能治喘而不用者。恶其发气也。
伤寒心下有水气。咳而微喘。发热不渴。服汤已。渴者。此寒去欲解也。小青龙汤主之。
内饮外寒。相得不解。气凌于肺。为咳而微喘。发热不渴。如上条之证也。是必以小青龙外解
寒邪。内消水饮为主矣。若服汤已。渴者。是寒外解而饮内行也。故为欲解。小青龙汤主之六字。
当在发热不渴下。
或问水饮之证。或渴或不渴云何。曰、水积于中。故不渴也。其渴者。水积一处。而不得四布也。
然而不渴者。常也。其渴者。变也。服小青龙汤已而渴者。乃寒去饮消之常道也。
Taiyang disease (disease of the Taiyang channel) exterior syndrome is not resolved, and there is fluid retention in the epigastrium. There is dry retching, fever accompanied by coughing, or thirst, or diarrhea, or a sensation of choking in the throat, or difficulty in urination with fullness in the lower abdomen, or wheezing.
Xiao Qing Long Tang (Minor Blue Dragon Decoction) is the primary treatment.
The exterior cold is not resolved, while there is retained fluid in the epigastrium. The fluid and cold pathogen contend with each other, rebelling between the Lung and Stomach, causing dry retching, fever, and coughing. This is a combined syndrome of Taiyang disease.
Fluid retention, as a pathological product, moves up and down with Qi, reaching everywhere. It may obstruct the upper, accumulate in the middle, or stagnate in the lower parts, manifesting as diseases according to its location. Although the treatment methods vary with additions and subtractions, they fundamentally do not go beyond the method of Xiao Qing Long Tang. Mahuang (Ephedrae Herba) and Guizhi (Cinnamomi Ramulus) disperse the cold pathogen invading from the exterior; Banxia (Pinelliae Rhizoma), Xixin (Asari Radix et Rhizoma), and Ganjiang (Zingiberis Rhizoma) eliminate the accumulated cold fluid internally; Shaoyao (Paeoniae Radix Alba) and Wuweizi (Schisandrae Fructus) restrain the acrid and drying nature of Mahuang and Guizhi, ensuring that the exterior-resolving and interior-resolving herbs coordinate without conflicting.
Formula: Xiao Qing Long Tang (Minor Blue Dragon Decoction)
Mahuang (Ephedrae Herba), Guizhi (Cinnamomi Ramulus), Shaoyao (Paeoniae Radix Alba), Xixin (Asari Radix et Rhizoma), Ganjiang (Zingiberis Rhizoma), Zhi Gancao (Prepared Glycyrrhizae Radix et Rhizoma) [each 3 liang], Wuweizi (Schisandrae Fructus), Banxia (Pinelliae Rhizoma) [each 0.5 sheng].
Take the above eight ingredients, add one dou of water, first boil Mahuang until the volume reduces by two sheng, remove the foam on the surface, then add the remaining herbs. Boil until three sheng remain, strain, and take one sheng warm.
Da Qing Long Tang (Major Blue Dragon Decoction) combines Mahuang Tang and Guizhi Tang with the addition of Shigao (Gypsum Fibrosum). It can release pathogens and relieve irritability. Xiao Qing Long Tang lacks Shigao but contains Banxia, Ganjiang, Shaoyao, Xixin, and Wuweizi. It can disperse cold pathogens and promote the movement of fluid retention. Both are called "Qing Long" (Blue Dragon) because they both possess the functions of inducing sweating and eliminating fluid retention. If heat is closed within the meridians, yet Shigao is not used, and sweat is blocked by heat, how could sweating be achieved? If cold fluid is latent inside, yet Ginger and Pinellia are not used, and cold contends with fluid, how could it be dispersed? Shaoyao and Wuweizi not only constrain rebellious Qi to calm the Lung Qi but also moderate the vigorous action of Mahuang, Guizhi, Ganjiang, and Xixin, preventing them from disturbing each other and instead fostering coordination to achieve synergistic effects between the interior and exterior.
Modifications:
If there is mild diarrhea, remove Mahuang and add Yuanhua (Genkwa Flos) boiled until reddish-brown, equivalent to the size of an egg.
Mild diarrhea indicates water dampness seeping into the stomach. For patients with diarrhea, the exterior should not be attacked with purgatives or strong diaphoretics; therefore, remove Mahuang which releases the exterior, and add Yuanhua which promotes water metabolism.
If there is thirst, remove Banxia and add Gualougen (Trichosanthis Radix) 3 liang.
Thirst indicates insufficient body fluids; therefore, remove the acrid and drying Banxia and add the bitter and moistening Gualougen. However, if thirst is caused by fluid retention failing to distribute properly, it might still be appropriate to retain Banxia to promote moisture flow and moisten dryness.
If there is a sensation of choking in the throat, remove Mahuang and add one Pao Fuzi (Prepared Aconiti Lateralis Radix), processed.
Choking indicates accumulation of cold fluid in the middle jiao. Fuzi is warm to dispel cold and acrid to break fluid retention, so it is added. Mahuang disperses Yang Qi and may increase cold in the Stomach, so it is removed.
If there is difficulty in urination and fullness in the lower abdomen, remove Mahuang and add Fuling (Poria) 4 liang.
Difficulty in urination and lower abdominal fullness indicate water accumulation in the lower jiao. Therefore, add Fuling to drain the accumulated water. Mahuang is not used because it might guide Qi upward, preventing water from descending.
If there is wheezing, remove Mahuang and add Xingren (Armeniacae Semen Amarum) peeled and free of kernels, 0.5 sheng.
Wheezing is caused by fluid qi affecting the Lung; therefore, add Xingren to direct Qi downward and drain the Lung. Although Mahuang can also treat wheezing, it is avoided here due to its tendency to scatter Qi excessively.
In Taiyang disease with fluid retention in the epigastrium, characterized by coughing with slight wheezing, fever, and no thirst, if the patient becomes thirsty after taking the decoction, this indicates that the cold pathogen has departed and the disease is about to resolve. [Note: The phrase "Xiao Qing Long Tang is the primary treatment" logically belongs after "fever and no thirst," not after "becomes thirsty."]
When internal fluid retention and external cold entangle each other and do not resolve, Qi rebels against the Lung, causing coughing with slight wheezing, fever, and no thirst, as described in the previous clause. The primary treatment must be Xiao Qing Long Tang to externally resolve the cold pathogen and internally eliminate fluid retention. If thirst occurs after taking the medicine, it signifies that the cold has been resolved from the exterior and the fluid is moving internally, indicating the disease is resolving. The six characters "Xiao Qing Long Tang is the primary treatment" should be placed after "fever and no thirst."
A question arises: Regarding fluid retention syndromes, why do some present with thirst and others without? The answer is: When fluid accumulates in the middle, there is typically no thirst. Thirst occurs when fluid is stagnant in one area and fails to distribute to the four directions. Generally, absence of thirst is the norm, while thirst is a variation. Becoming thirsty after taking Xiao Qing Long Tang represents the normal progression of cold departure and fluid resolution.