内经曰。肝生于左。肺藏于右。心位在上。肾处在下。左右上下。四脏居焉。脾者土也。
应中央。处四脏之中。为中州。治中焦。生育荣卫。通行津液。一有不调。则荣卫失所
育。津液失所行。必以此汤温建中脏。是以建中名焉。胶饴味甘温。甘草味甘平。脾
欲缓。急食甘以缓之。建脾者。必以甘为主。故以胶饴为君。甘草为臣。桂辛热。辛、散
也。润也。荣卫不足。润而散之。芍药味酸微寒。酸、收也。泄也。津液不逮。收而行之。是
以桂芍药为佐。生姜味辛温。大枣味甘温。胃者卫之源。脾者荣之本。黄帝针经曰。
荣出中焦。卫出上焦是矣。卫为阳。不足者益之必以辛。荣为阴。不足者补之必以
甘。辛甘相合。脾胃健而荣卫通。是以姜枣为使。或谓桂枝汤解表。而芍药数少。建
中汤温里。而芍药数多。殊不知二者远近之制。皮肤之邪为近。则制小其服也。桂
枝汤芍药佐桂枝同用散。非与建中同体尔。心腹之邪为远。则制大其服也。建中
汤芍药佐胶饴以建脾。非与桂枝同用尔。内经曰。近而奇偶。制小其服。远而奇偶。
制大其服。此之谓也。
胶饴（君一升） 甘草（臣一两炙） 桂枝（佐三两去皮） 芍药（佐六两） 大枣（使十二枚擘） 生姜（使三
两切）
上六味。以水七升。煮取三升。去渣。内胶饴。更上微火消解。温服一升。日三服。
呕家不用建中汤。以甜故也。
《内经》说：肝气生于左侧，肺气藏于右侧，心位于上部，肾处于下部。左、右、上、下四个方位，四脏分别居于其中。脾属土，对应中央，处于四脏之中，称为中州，主管中焦，化生营卫之气，通行津液。一旦功能不调，就会导致营卫失去化生的基础，津液失去通行的动力，必须用此汤来温补并建立中脏的功能，因此命名为建中汤。
胶饴（麦芽糖）味甘性温，甘草味甘性平。脾的生理特性是喜缓急，紧急时用甘味食物来缓和它。要健运脾脏，必须以甘味药为主，所以用胶饴作为君药，甘草作为臣药。桂枝辛热，辛能发散，也能润养。当营卫不足时，通过润养和发散来调和。芍药味酸微寒，酸能收敛，也能泄降。当津液运行不及（滞涩）时，通过收敛和推动来使其运行。因此，桂枝和芍药作为佐药。生姜味辛温，大枣味甘温。胃是卫气的源头，脾是营气的根本。《黄帝针经》说：“营气出于中焦，卫气出于上焦”，正是这个意思。卫气属阳，阳气不足者补充时必须用辛味；营气属阴，阴气不足者补益时必须用甘味。辛味与甘味相互结合，脾胃功能强健，营卫之气通畅，因此生姜和大枣作为使药。
有人问：桂枝汤用于解表，其中芍药用量较少；建中汤用于温里，其中芍药用量较多。这其实不知道二者在制剂远近上的区别。皮肤之邪属于“近”病，所以制剂小其服用量。桂枝汤中芍药辅助桂枝共同使用以发散表邪，这与建中汤的机理不同。心腹之邪属于“远”病，所以制剂大其服用量。建中汤中芍药辅助胶饴以健脾，这也与桂枝汤不同。《内经》说：“病位近而配伍为奇偶（单数或双数），则制小其服；病位远而配伍为奇偶，则制大其服。”说的就是这个道理。
胶饴（君药，一升） 甘草（臣药，一两，炙用） 桂枝（佐药，三两，去皮） 芍药（佐药，六两） 大枣（使药，十二枚，掰开） 生姜（使药，三两，切片）
以上六味药，用水七升，煮取三升，去渣滓，加入胶饴，再用小火微火加热使其溶解。每次温服一升，每日三次。
The *Neijing* (Inner Canon) states: The liver qi arises on the left, the lung qi is stored on the right, the heart is located superiorly, and the kidney is situated inferiorly. The four viscera occupy these four positions: left, right, superior, and inferior. The spleen belongs to Earth, corresponds to the Center, resides among the four viscera, is termed the "Middle State" (Zhongzhou), governs the Middle Jiao, generates Ying (Nutrient) Qi and Wei (Defensive) Qi, and circulates Jin-Ye (Body Fluids). If there is any dysfunction, Ying and Wei Qi will lose their source of generation, and Body Fluids will lose their pathway of circulation. Therefore, this decoction must be used to warm and establish the function of the central viscera; hence it is named Jianzhong Tang (Middle-Establishing Decoction).
Jiaoyi (Maltose) has a sweet flavor and warm nature; Gancao (Licorice Root) has a sweet flavor and neutral nature. The spleen desires relaxation; in cases of urgency, one should eat sweet substances to relax it. To build the spleen, one must primarily use sweet herbs. Thus, Jiaoyi is used as the Jun (Sovereign) herb, and Gancao as the Chen (Minister) herb. Guizhi (Cinnamon Twig) is acrid and hot. Acridness disperses and moistens. When Ying and Wei Qi are insufficient, they are treated by moistening and dispersing. Shaoyao (Peony Root) has a sour flavor and slightly cold nature. Sourness astringes and drains. When Body Fluids fail to reach their destination, they are treated by astringing and promoting their movement. Therefore, Guizhi and Shaoyao are used as Zuo (Assistant) herbs. Shengjiang (Fresh Ginger) has an acrid and warm flavor; Dazao (Jujube Fruit) has a sweet and warm flavor. The Stomach is the source of Wei Qi, and the Spleen is the root of Ying Qi. The *Huangdi Zhenjing* (Yellow Emperor’s Classic of Acupuncture) states: "Ying Qi emerges from the Middle Jiao, and Wei Qi emerges from the Upper Jiao." This is correct. Wei Qi is Yang; when Yang is insufficient, tonification must utilize acrid substances. Ying Qi is Yin; when Yin is insufficient, tonification must utilize sweet substances. When acrid and sweet flavors combine, the Spleen and Stomach become robust, and Ying and Wei Qi flow freely. Therefore, Shengjiang and Dazao are used as Shi (Envoy) herbs.
Some argue: Guizhi Tang (Cinnamon Twig Decoction) releases the exterior, yet contains a small amount of Shaoyao; Jianzhong Tang warms the interior, yet contains a large amount of Shaoyao. They do not understand the principle of formulation based on proximity or distance. Pathogens in the skin and hair are considered "proximal," so the dosage is made smaller. In Guizhi Tang, Shaoyao assists Guizhi in dispersing pathogens; this is not the same mechanism as in Jianzhong Tang. Pathogens in the heart and abdomen are considered "distal," so the dosage is made larger. In Jianzhong Tang, Shaoyao assists Jiaoyi in building the Spleen; this is also not the same usage as with Guizhi. The *Neijing* states: "When the disease is proximal, whether the formula is odd or even, make the dosage small; when the disease is distal, whether the formula is odd or even, make the dosage large." This refers to that principle.
Jiaoyi (Jun, 1 sheng) Gancao (Chen, 1 liang, prepared by stir-frying) Guizhi (Zuo, 3 liang, bark removed) Shaoyao (Zuo, 6 liang) Dazao (Shi, 12 pieces, split open) Shengjiang (Shi, 3 liang, sliced)
Take the above six ingredients. Add seven sheng of water, boil to obtain three sheng, remove the dregs, add Jiaoyi, and heat gently over a low fire until dissolved. Take one sheng warm, three times daily.
Patients who vomit should not use Jianzhong Tang because of its sweetness.