主治结滞水毒也。旁治呕吐嗽、下利厥冷、烦躁腹痛、胸痛腰痛。
考 证
大建中汤证曰∶心胸中大寒、痛呕不能饮食。
苓姜术甘汤证曰∶身体重、腰中冷。又云∶腰以下冷痛。
半夏干姜散证曰∶干呕吐逆、吐涎沫。
以上三方，干姜或四两，或诸药等分。
人参汤证曰∶喜唾。又曰∶心中痞。
通脉四逆汤证曰∶下利清谷。又曰∶手足厥逆。又云∶干呕。
小青龙汤证曰∶心下有水气、干呕。又云∶咳。
半夏泻心汤证曰∶呕而肠鸣。
柴胡姜桂汤证曰∶胸胁满。又云∶心烦。
黄连汤证曰∶腹中痛欲呕吐。
苓甘五味姜辛汤证曰∶咳胸满。
干姜黄连黄芩人参汤证曰∶吐下。
六物黄芩汤证曰∶干呕下利。
以上九方，干姜皆三两。
栀子干姜汤证曰∶微烦。
甘草干姜汤证曰∶厥，咽中干、烦躁吐逆。
干姜附子汤证曰∶烦躁、不得眠。
以上三方，干姜二两、一两，而四两之例。
四逆汤证曰∶下利清谷。又曰∶手足厥冷。
以上一方，干姜一两半，而三两之例。
桃花汤证曰∶下利。
干姜人参半夏丸证曰∶呕吐不止。
以上二方，干姜一两，而三两之例。
上历观此诸方，其呕吐者，咳者、痛者、下利者之等，壹是皆水毒之结滞者也。
互 考
孙思邈曰∶无生姜，则以干姜代之。以余观之，仲景氏用生姜、干姜，其所主治，大同
而小异；生姜主呕吐，干姜主水毒之结滞者也，不可混矣。
辨 误
本草以干姜为大热，于是世医皆谓四逆汤方中，姜、附热药也，故能温厥冷，非也。按
厥冷者，毒之急迫也，故甘草以为君，而姜、附以为佐，其用姜、附者，以逐水毒也。何热
之有？京师二条路白山街，有嘉兵卫者，号近江铺，其男年始十有三，一朝而下利，及至日
午，无知其行数，于是神气困冒，医为独参汤与之。及至日晡所，手足厥冷，医大惧，用姜、
附益多，而厥冷益甚，诸医皆以为不治。余为诊之，百体无温、手足擗地、烦躁而叫号、如
有腹痛之状、当脐有动、手不可近。余乃谓曰∶是毒也！药可以治焉。知其死生，则我不知
之也；虽然，今治亦死，不治亦死，等死，死治可乎？亲戚许诺。乃与大承气汤，（一帖之
重十二钱）一服。不知，复与，厥冷则变为热、三服而神色反正，下利减半。服十日所，诸
证尽退。由是观之医之于事知此药，解此毒耳。毒之解也，厥冷者温，大热者凉。若以厥冷
复常为热药，则大黄、芒硝，亦为热药乎？药物之寒热温凉不可论，斯可以知已。
品 考
干姜 本邦之产有二品，曰干生姜、曰三河干姜。所谓干生姜者，余家用之。所谓三河
干姜者，余家不用之。
主治水湿毒邪的凝结阻滞。兼治呕吐、咳嗽、腹泻伴四肢厥冷、烦躁腹痛、胸痛及腰痛。
考证：
大建中汤证表现为：心胸部位剧烈寒冷疼痛，呕吐无法进食。
苓姜术甘汤证表现为：身体沉重，腰部发冷；又说：腰部以下冷痛。
半夏干姜散证表现为：干呕逆气，吐出涎沫。
以上三个方剂中，干姜用量分别为四两，或与其他药物等量。
人参汤证表现为：喜欢吐唾沫。又说：心中痞塞感。
通脉四逆汤证表现为：腹泻排出未消化的食物。又说：手足冰冷逆冷。又说：干呕。
小青龙汤证表现为：心下有停饮（水气），干呕。又说：咳嗽。
半夏泻心汤证表现为：呕吐且肠鸣。
柴胡姜桂汤证表现为：胸胁部胀满。又说：心烦。
黄连汤证表现为：腹中疼痛想呕吐。
苓甘五味姜辛汤证表现为：咳嗽且胸部胀满。
干姜黄连黄芩人参汤证表现为：呕吐和腹泻。
六物黄芩汤证表现为：干呕和腹泻。
以上九个方剂中，干姜用量均为三两。
栀子干姜汤证表现为：轻微烦躁。
甘草干姜汤证表现为：四肢厥冷，咽喉干燥，烦躁并伴有呕吐逆气。
干姜附子汤证表现为：烦躁，无法入睡。
以上三个方剂中，干姜用量为二两、一两，这是四两用法的变例。
四逆汤证表现为：腹泻排出未消化的食物。又说：手足冰冷。
以上一个方剂中，干姜用量为一两半，这是三两用法的变例。
桃花汤证表现为：腹泻。
干姜人参半夏丸证表现为：呕吐不止。
以上两个方剂中，干姜用量为一两，这是三两用法的变例。
综上所述观察这些方剂，其中的呕吐、咳嗽、疼痛、腹泻等症状，全都是由于水湿毒邪凝结阻滞所致。
互考：
孙思邈说：如果没有生姜，就用干姜代替。据我观察，张仲景使用生姜和干姜，它们的主治功效大体相同而略有差异；生姜主治呕吐，干姜主治水湿毒邪的凝结阻滞，不可混淆。
辨误：
本草书籍认为干姜是大热之药，因此世间的医生都认为在四逆汤方中，干姜和附子是热性药物，所以能温暖四肢厥冷，这是错误的。按我的理解，四肢厥冷是毒邪急迫的表现，所以以甘草为君药，干姜和附子为佐药，使用干姜和附子的目的，是为了驱逐水湿毒邪。哪里有什么热性呢？
京都二条路白山街有一位名叫嘉兵卫的人，店铺名为近江铺，他的儿子年仅十三岁，一天突然发生腹泻，到了中午，不知道去了多少次厕所，于是神志困顿昏蒙，医生给他服用了独参汤。到了傍晚时分，出现手足厥冷，医生非常恐惧，加大了干姜和附子的用量，结果四肢厥冷更加严重，其他医生都认为是无法治愈的绝症。我为他诊脉，发现全身无温，手足痉挛贴地，烦躁不安并大声呼叫，好像有腹痛的样子，肚脐周围有搏动感，手不能靠近。我便说道：这是毒邪作祟！药物可以治疗它。至于能否治好，我不确定；虽然如此，现在治疗也是死，不治疗也是死，同样是死，不如尝试治疗如何？家属答应了。于是给他服用大承气汤（一帖重十二钱），服了一次。未见明显效果，再次服用，四肢厥冷转变为发热，服用三次后神色恢复正常，腹泻减半。服药十天后，所有症状完全消退。由此看来，医生对于此药的作用，只是了解它能解此毒罢了。毒邪解除后，四肢厥冷者转温，大热者转凉。如果把四肢厥冷恢复常态归因于热性药物，那么大黄、芒硝难道也是热性药物吗？药物的寒热温凉属性是不可简单论断的，由此可以明白了。
It governs the stagnation and accumulation of dampness-toxin. It also treats vomiting, coughing, diarrhea with cold extremities, irritability, abdominal pain, chest pain, and lower back pain.
Evidence:
In the syndrome of Da Jian Zhong Tang (Greatly Building Middle Decoction), there is severe cold in the heart and chest, pain, vomiting, and inability to eat.
In the syndrome of Ling Jiang Zhu Gan Tang (Poria, Ginger, Atractylodes Macrocephala, and Licorice Decoction), the body feels heavy, and the waist is cold. It also states that the area below the waist is cold and painful.
In the syndrome of Ban Xia Gan Jiang San (Pinellia and Dried Ginger Powder), there is dry retching, regurgitation, and spitting of saliva.
In these three formulas, the dosage of Gan Jiang (Dried Ginger) is either four qian or equal to other herbs.
In the syndrome of Ren Shen Tang (Ginseng Decoction), there is a tendency to spit saliva. It also states there is a feeling of痞 (stagnation/blockage) in the heart.
In the syndrome of Tong Mai Si Ni Tang (Unblocking Pulse and Reversing Extremities Decoction), there is diarrhea with undigested food. It also states cold extremities. It also mentions dry retching.
In the syndrome of Xiao Qing Long Tang (Minor Blue Dragon Decoction), there is water-fluid retention in the epigastrium and dry retching. It also mentions coughing.
In the syndrome of Ban Xia Xie Xin Tang (Pinellia Drain the Epigastrium Decoction), there is vomiting accompanied by borborygmus (intestinal rumbling).
In the syndrome of Chai Hu Jiang Gui Tang (Bupleurum, Ginger, and Cinnamon Twig Decoction), there is fullness in the chest and hypochondrium. It also mentions irritability.
In the syndrome of Huang Lian Tang (Coptis Decoction), there is abdominal pain with a desire to vomit.
In the syndrome of Ling Gan Wu Wei Jiang Xin Tang (Poria, Glycyrrhiza, Schisandra, Dried Ginger, and Asarum Decoction), there is coughing and chest fullness.
In the syndrome of Gan Jiang Huang Lian Huang Qin Ren Shen Tang (Dried Ginger, Coptis, Scutellaria, and Ginseng Decoction), there is vomiting and diarrhea.
In the syndrome of Liu Wu Huang Qin Tang (Six-Ingredient Scutellaria Decoction), there is dry retching and diarrhea.
In these nine formulas, the dosage of Gan Jiang (Dried Ginger) is consistently three qian.
In the syndrome of Zhi Zi Gan Jiang Tang (Gardenia and Dried Ginger Decoction), there is slight irritability.
In the syndrome of Gan Cao Gan Jiang Tang (Licorice and Dried Ginger Decoction), there are cold extremities, dry throat, irritability, and vomiting with regurgitation.
In the syndrome of Gan Jiang Fu Zi Tang (Dried Ginger and Aconite Decoction), there is irritability and insomnia.
In these three formulas, the dosages of Gan Jiang (Dried Ginger) are two qian and one qian, representing variations from the four-qian standard.
In the syndrome of Si Ni Tang (Reversing Extremities Decoction), there is diarrhea with undigested food. It also states cold extremities.
In this single formula, the dosage of Gan Jiang (Dried Ginger) is one and a half qian, representing a variation from the three-qian standard.
In the syndrome of Tao Hua Tang (Peach Blossom Decoction), there is diarrhea.
In the syndrome of Gan Jiang Ren Shen Ban Xia Wan (Dried Ginger, Ginseng, and Pinellia Pill), there is incessant vomiting.
In these two formulas, the dosage of Gan Jiang (Dried Ginger) is one qian, representing a variation from the three-qian standard.
Having observed all these formulas comprehensively, the symptoms such as vomiting, coughing, pain, and diarrhea are all caused by the stagnation and accumulation of dampness-toxin.
Mutual Examination:
Sun Simiao stated: "If fresh ginger is unavailable, dried ginger may be used as a substitute." In my observation, Zhang Zhongjing's use of Sheng Jiang (Fresh Ginger) and Gan Jiang (Dried Ginger) has similar main indications but minor differences; Sheng Jiang (Fresh Ginger) primarily treats vomiting, while Gan Jiang (Dried Ginger) primarily treats the stagnation of dampness-toxin. They should not be confused.
Correcting Misconceptions:
Bencao materia medica describes Gan Jiang (Dried Ginger) as extremely hot. Consequently, physicians of the world believe that in Si Ni Tang (Reversing Extremities Decoction), Jiang (Ginger) and Fu Zi (Aconite) are hot medicines, and thus they can warm cold extremities. This is incorrect. Cold extremities are a manifestation of urgent toxin pressure. Therefore, Gan Cao (Licorice) is used as the sovereign herb, while Jiang (Ginger) and Fu Zi (Aconite) are used as assistant herbs. The purpose of using Jiang (Ginger) and Fu Zi (Aconite) is to expel dampness-toxin. Where is the heat?
In Nihonbashi, Byoin Street, Kyoto, there was a man named Kabe Emon, whose shop was called Omiya. His son was thirteen years old. One day, he suffered from diarrhea. By noon, he had lost count of how many times he went to the toilet. His spirit became exhausted and confused. A physician administered Du Shen Tang (Single Ginseng Decoction). By dusk, his extremities became cold. The physician was terrified and increased the dosage of Gan Jiang (Dried Ginger) and Fu Zi (Aconite), but the cold extremities worsened. Other physicians deemed it incurable. I examined him and found his entire body devoid of warmth, his limbs spasmodic against the ground, irritability with loud crying, signs resembling abdominal pain, pulsation around the umbilicus, and tenderness to touch. I said, "This is toxin! Medication can treat it. Whether he lives or dies, I cannot predict; however, treating him now leads to death, and not treating him also leads to death. Since death is inevitable, would you prefer treatment?" The relatives agreed. I then administered Da Cheng Qi Tang (Major Order the Qi Decoction) (one packet weighing twelve qian). After one dose, there was no significant change. I administered another dose. The cold extremities turned into heat. After three doses, his complexion and spirit returned to normal, and diarrhea decreased by half. After ten days of medication, all symptoms subsided. From this, we see that the physician's understanding of this medicine was merely its ability to resolve this toxin. When the toxin resolves, cold extremities become warm, and extreme heat becomes cool. If one attributes the normalization of cold extremities to hot medicines, are Da Huang (Rhubarb) and Mang Xiao (Mirabilite) also hot medicines? The hot, cold, warm, and cool properties of medicines cannot be simply discussed; this clarifies the matter.
Product Examination:
Gan Jiang (Dried Ginger): There are two varieties produced in our country: Gan Sheng Jiang (Dried Fresh Ginger) and Mikawa Gan Jiang (Mikawa Dried Ginger). The variety known as Gan Sheng Jiang (Dried Fresh Ginger) is what my family uses. The variety known as Mikawa Gan Jiang (Mikawa Dried Ginger) is not used by my family.