仲景曰∶太阳中风，头痛，阳浮而阴弱，阳浮者，热自发，阴弱者，汗自出，啬
啬恶寒，淅淅恶风，翕翕发热，鼻鸣干呕，本方主之。古人用辛散者，必用酸收，故桂
枝汤中用芍药，犹兵家之节制也。
桂枝 芍药 生姜（各三两） 甘草（二两，炙） 大枣（十二枚，去核） 水七升，
微火煮取三升，服一升，覆令微汗，不可令如水淋漓。若汗出病瘥，不必尽剂。若不汗
更服至二三剂。
仲景以发汗为重，解肌为轻，中风不可大汗，过汗则反动营血，虽有表邪，只可解
肌，故以桂枝汤少和之也。
成氏曰∶阳脉浮者，卫中风也。阴脉弱者，荣气弱也。风并于卫，卫实而荣虚，故
发热汗出。卫虚则恶风，荣虚则恶寒，荣弱卫强，恶寒复恶风者，以汗出则腠理疏，亦
恶风也。翕翕者。若合羽所覆，热在表也。鼻鸣干呕者，风壅气逆也。与桂枝汤和荣卫
而散风邪，桂味辛热用以为君者，桂犹圭也，宣导诸药为之先聘，辛甘发散为阳之义
也。芍药味苦酸寒，甘草甘平，用以为臣佐者。《经》曰∶风淫所胜，平以辛凉，佐以
苦甘，以甘缓之，以酸收之，桂枝辛甘为阳，臣以芍药之酸收，佐以甘草之甘平，不
令走泄阴气也。生姜辛温能散，大枣甘温能和，二物为使者，《经》曰∶风淫于内，以
甘缓之，以辛散之也。姜枣固能发散，此又不专发散之用，又以行脾之津液而和荣卫者
也，麻黄汤不用姜枣专于发汗，则不待行化而津液得通矣。
夫卫属阳，阳气者，不能卫外而为固则有汗。成云，卫实何耶？盖邪气盛则实，非
正气也。既曰∶邪实则热在表矣，其恶风又何耶？盖汗能开腠，故也。既曰∶热在表则
汗出而腠开，亦宜解矣。乃不解者，又何耶？赵嗣真所谓惟脏腑可分表里，皮肤骨
髓，但分浮、浅、深、沉，俱属于表。若以皮肤为表，骨髓则为里，则麻黄汤症，骨节
疼痛，其可谓有表，复有里耶？然则不解者，骨髓之邪自在，正与啬啬恶寒之义相
合，所谓热在皮肤，寒在骨髓也。如骨髓无寒，则桂枝不宜与矣。《论》曰∶桂枝下咽，
阳盛则毙，其此之谓乎？
张仲景说：太阳中风证，出现头痛，脉象浮取有力而沉取无力（阳浮而阴弱）。所谓“阳浮”，是指发热自然发生；所谓“阴弱”，是指汗液自然流出。患者表现为怕冷时瑟瑟发抖（啬啬恶寒），怕风时如淋雨般战栗（淅淅恶风），发热时感觉身体像被羽毛覆盖一样温热（翕翕发热），伴有鼻鸣和干呕，本方主治此证。古人使用辛味发散药时，必定配合酸味收敛药，所以桂枝汤中使用芍药，这就像用兵打仗中的节制与约束一样。
桂枝、芍药、生姜（各三两），甘草（二两，炙烤），大枣（十二枚，去核）。用水七升，用小火煮取三升，每次服用一升，服药后覆盖衣被使身体微微出汗，不可让汗水像水淋漓那样大量流出。如果出汗后病愈，不必服完剩余的药汁。如果没有出汗，可再服用，直至二三剂。
张仲景认为发汗是重法，解肌是轻法。中风证不可大汗，因为大汗会扰动营血，即使有表邪，也只能采用解肌的方法，所以用桂枝汤轻微调和营卫。
成无己说：脉象浮取有力的，是卫气感受风邪。脉象沉取无力的，是营气虚弱。风邪并入卫分，导致卫气实而营气虚，所以出现发热和汗出。卫气虚则怕风，营气虚则怕冷。营弱卫强，既怕冷又怕风，是因为出汗导致腠理疏松，同时也怕风。“翕翕”形容发热，如同羽毛覆盖在身上，热在体表。鼻鸣和干呕，是风邪壅滞导致气机逆乱。给予桂枝汤以调和营卫并疏散风邪。桂枝味辛性热，作为君药，因为“桂”通“圭”，意为宣导诸药成为先导，符合“辛甘发散为阳”的道理。芍药味苦、酸、寒，甘草味甘、平，作为臣佐药。《内经》说：“风邪过盛，用辛凉之品平抑它，用苦甘之品辅助它，用甘味缓急，用酸味收敛。”桂枝辛甘属阳，臣药用芍药的酸收，佐药用甘草的甘平，不令阴气耗散。生姜辛温能发散，大枣甘温能和缓，这两味药作为使者，《内经》说：“风邪在内，用甘味缓急，用辛味发散。”姜和大枣固然能发散，但此处不仅仅用于发散，还用来运行脾脏的津液从而调和营卫。麻黄汤不用姜枣，专门用于发汗，那么就不需要依靠姜枣来行化，津液自然通畅了。
卫气属于阳，阳气如果不能固护于外，就会出汗。成无己说“卫实”是什么意思？大概是指邪气盛实，并非正气实。既然说邪气实则热在体表，那为什么还会怕风呢？大概是因为汗能打开腠理所致。既然说热在体表则汗出且腠理开，按理说应该解除了。为何没有解除呢？赵嗣真所说只有脏腑可以分表里，皮肤骨髓只是分为浮、浅、深、沉，都属于表。如果把皮肤当作表，骨髓当作里，那么麻黄汤证中骨节疼痛，能说既有表证又有里证吗？然而之所以不解，是因为骨髓中的邪气依然存在，这与“啬啬恶寒”的意义相符合，即所谓“热在皮肤，寒在骨髓”。如果骨髓中没有寒邪，那么就不适宜用桂枝汤了。《伤寒论》说：“桂枝汤喝下去，如果是阳盛体质则会致死”，说的就是这个道理吧？
Zhang Zhongjing stated: In Taiyang Wind-Strike (Taiyang Fengzhong, a syndrome caused by wind pathogen invading the Taiyang channel), headache occurs. The pulse is floating and forceful at superficial position but weak at deep position (Yang floating and Yin weak). "Yang floating" indicates spontaneous heat generation; "Yin weak" indicates spontaneous sweating. The patient exhibits shivering aversion to cold (Sese Ehan, feeling chilly and trembling), shivering aversion to wind (Xixi Efeng, feeling cold as if being rained upon), and mild fever with a sensation of warmth under the skin like being covered by feathers (Xixi Fare). Accompanied by nasal congestion/murmur (Biming) and dry retching (Gan'ou), this formula is indicated. Ancient practitioners used sour-astringent herbs alongside acrid-dispersing ones; thus, Shaoyao (Paeoniae Radix Alba) is used in Guizhi Tang (Cinnamon Twig Decoction), analogous to military discipline and restraint.
Guizhi (Cinnamomi Ramulus), Shaoyao (Paeoniae Radix Alba), Shengjiang (Zingiberis Rhizoma Recens) (each 3 liang), Gancao (Glycyrrhizae Radix et Rhizoma, roasted) (2 liang), Dazao (Jujubae Fructus) (12 pieces, pitted). Boil in 7 sheng of water, simmer over low heat until reduced to 3 sheng. Take 1 sheng per dose. After ingestion, cover with blankets to induce slight perspiration; do not allow profuse sweating resembling dripping water. If symptoms resolve after sweating, there is no need to finish the remaining decoction. If no sweat occurs, administer again, up to two or three doses.
Zhang Zhongjing considered profuse sweating a heavy method and relieving muscle tension (Jieji) a light method. Wind-strike should not be treated with profuse sweating, as excessive sweating may disturb Ying-Blood. Even with exterior pathogens, only Jieji (relieving muscle layer) is appropriate; therefore, Guizhi Tang is used to gently harmonize Ying and Wei.
Cheng Wuji stated: A floating pulse indicates Wei-Qi affected by wind. A weak pulse indicates deficient Ying-Qi. When wind merges into the Wei level, Wei becomes excess while Ying becomes deficient, resulting in fever and sweating. Deficient Wei leads to aversion to wind; deficient Ying leads to aversion to cold. With Ying deficiency and Wei excess, both aversion to cold and wind occur because sweating causes porosity of Couli (skin pores), leading to further aversion to wind. "Xixi" describes fever resembling warmth under feather covering, indicating heat in the exterior. Nasal murmur and dry retching result from wind obstruction causing Qi rebellion. Guizhi Tang is given to harmonize Ying and Wei and disperse wind pathogen. Guizhi is acrid and hot, serving as the Sovereign herb. "Gui" sounds like "Gui" (jade tablet), implying guiding other herbs as pioneers, consistent with the principle that "acrid and sweet disperse for Yang." Shaoyao is bitter, sour, and cold; Gancao is sweet and neutral, serving as Minister and Assistant herbs. The Classic states: "For excessive wind, use acrid-cool to pacify, assist with bitter-sweet, use sweet to relax, and sour to astringe." Guizhi is acrid-sweet and Yang; its minister Shaoyao provides sour astringency, and assistant Gancao provides sweet neutrality, preventing leakage of Yin Qi. Shengjiang is acrid-warm and dispersing; Dazao is sweet-warm and harmonizing. These two act as Envoys. The Classic states: "For wind inside, use sweet to relax and acrid to disperse." Although Ginger and Jujube can disperse, here they are not solely for dispersion but to circulate Spleen fluids and harmonize Ying and Wei. Mahuang Tang does not use Ginger and Jujube, focusing purely on sweating, so fluid transformation is unnecessary as fluids flow freely.
Wei belongs to Yang. If Yang Qi cannot protect the exterior and consolidate, sweating occurs. Cheng said "Wei excess," what does this mean? It refers to pathogenic excess, not healthy Qi excess. Since pathogenic excess implies heat in the exterior, why is there aversion to wind? This is because sweat opens the Couli. Since heat in the exterior causes sweating and open Couli, one might expect resolution. Why does it not resolve? Zhao Sizhen argued that only Zang-Fu organs have interior-exterior distinctions; skin and bone marrow are merely superficial, shallow, deep, and sinking, all belonging to the exterior. If skin is exterior and bone marrow is interior, then in Mahuang Tang syndrome with bone-joint pain, could one say there is both exterior and interior? However, the lack of resolution is due to pathogen remaining in the bone marrow, consistent with "shivering aversion to cold," meaning "heat in the skin, cold in the bone marrow." If there were no cold in the bone marrow, Guizhi Tang would be inappropriate. The Treatise says: "Once Guizhi Tang enters the throat, if Yang is excess, death ensues." This refers to such cases.