书曰∶无汗宜桂枝汤者，是用桂枝以发汗也。复曰∶无汗不得服桂枝。又曰∶发汗
过多者，却用桂枝甘草汤，是用桂枝以闭汗也。其一药二用者何说？盖桂为百药长，善
通血脉，故用以止烦出汗者，非桂能开腠理而发出汗也，以其调荣血，则卫气自和，邪
无容地遂自汗出而解矣。汗多用桂枝者，亦非桂枝能闭腠理而止汗也，以其调和荣卫，
则邪从汗出，邪去而汗自止矣。昧者不解其止汗发汗之意。凡见病者，便用桂枝，殊不
知，如遇太阳伤风自汗者，及中风自汗者，固获奇效，倘系太阳伤寒无汗，而骨髓无寒
者，而亦用之，为害岂浅浅乎？故仲景曰∶无汗不得服桂枝；又曰∶桂枝下咽，阳盛则毙者此耳。
麻黄得桂枝，则能发汗，芍药得桂枝，则能止汗，黄 得白术则止虚汗，防风得羌
活则治诸风，苍术得羌活则止身痛。柴胡得黄芩治热，附子得干姜治寒，羌活得川芎则
止头疼，川穹得天麻则止头眩，干葛得天花粉则止消渴，石膏得知母则止渴，香薷得扁
豆则消暑，黄芩得连翘则消毒，桑皮得苏子则止喘，杏仁得五昧则止嗽，丁香得柿蒂、
干姜则止呃，干姜得半夏则止呕，半夏得姜汁则回痰，贝母得栝蒌则开结痰，桔梗得升
麻开提血气，枳实得黄连则消心下痞，枳壳得桔梗能使胸中宽，知母、黄柏得山栀则降
火，豆豉得山栀则治懊 ，辰砂得酸枣则安神，白术得黄芩则安胎，陈皮得白术则补
脾，人参得五昧、麦冬则生肾水，苍术得香
附开郁结，浓朴得腹皮开膨胀，草果得山楂消肉积，神曲得麦芽能消食，乌梅得干葛则
消酒，砂仁得枳壳则宽中，木香得姜汁则散气，乌药得香附则顺气，芍药得甘草治腹痛
因虚，吴茱萸得良姜止腹痛因寒，乳香得没药大止诸痛，芥子得青皮治胁痛，黄 得大
附子则补阳，知母、黄柏得当归则补阴，当归得生地则生血，藕汁磨京墨则止血，红花
得当归则活血，归尾得桃仁则破血，大黄得芒硝则润下，皂荚得麝香则通窍，诃子得肉
果则止泻，木香得槟榔治后重，泽泻得猪芩则能利水，泽泻得白术则能收湿，此用药相
得之大端也。
《内经》中说：无汗症适宜用桂枝汤，这是利用桂枝来发汗。又说：无汗症不得服用桂枝汤。还说：发汗过多的患者，却使用桂枝甘草汤，这是利用桂枝来止汗。同一种药物有两种不同的功效，这是什么道理呢？原来桂枝被称为“百药长”，善于通行血脉，所以用它来止烦、出汗，并不是桂枝能直接打开腠理（皮肤毛孔）而发出汗液，而是因为它调和营血（运行于脉中的血液），使得卫气（行于脉外，具有保卫作用的气）自然和谐，邪气没有容身之地，于是身体自然出汗而病愈。发汗过多后用桂枝的，也不是桂枝能直接闭合腠理而止汗，而是因为它调和营卫，使得邪气随汗排出，邪气去除后汗液自然停止。愚昧的人不理解它既能止汗又能发汗的道理。凡是见到病人，就随意使用桂枝，殊不知，如果遇到太阳伤风自汗的患者，以及中风自汗的患者，固然能获得奇效；但如果属于太阳伤寒无汗，且骨髓中并无寒邪的患者，也使用它，造成的危害难道不大吗？所以张仲景说：无汗不得服用桂枝汤；又说：桂枝汤喝下去，如果是阳热亢盛的体质就会致死，说的就是这个道理。
麻黄得到桂枝，就能发汗；芍药得到桂枝，就能止汗；人参得到白术，就能止虚汗；防风得到羌活，就能治疗各种风邪；苍术得到羌活，就能缓解身体疼痛。柴胡得到黄芩，能治疗热证；附子得到干姜，能治疗寒证；羌活得川芎，能止头痛；川穹得天麻，能止头晕目眩；干葛（葛根）得天花粉，能止消渴症；石膏得知母，能止口渴；香薷得到扁豆，能消暑气；黄芩得到连翘，能解毒；桑皮得到苏子，能止喘咳；杏仁得到五味子，能止咳；丁香得到柿蒂和干姜，能止呃逆；干姜得到半夏，能止呕吐；半夏得到姜汁，能化痰；贝母得到栝蒌，能化解结聚之痰；桔梗得到升麻，能提升气血；枳实得到黄连，能消除心下痞满；枳壳得到桔梗，能使胸中宽畅；知母、黄柏得到山栀，能降火；豆豉得到山栀，能治疗心中烦闷不安；辰砂得到酸枣仁，能安神；白术得到黄芩，能安胎；陈皮得到白术，能补脾；人参得到五味子和麦冬，能滋生肾水；苍术得到香附，能开通郁结；厚朴得到腹皮（大腹皮），能消除胀满；草果得到山楂，能消除肉食积滞；神曲得到麦芽，能消化食物；乌梅得到干葛，能解酒毒；砂仁得到枳壳，能宽中理气；木香得到姜汁，能散气；乌药得到香附，能顺气；芍药得到甘草，能治疗因虚引起的腹痛；吴茱萸得到良姜，能治疗因寒引起的腹痛；乳香得到没药，能大大缓解各种疼痛；芥子得到青皮，能治疗胁痛；黄芪得到大附子，能补阳气；知母、黄柏得到当归，能补阴血；当归得到生地，能生血；藕汁磨京墨，能止血；红花得到当归，能活血；归尾得到桃仁，能破血；大黄得到芒硝，能润下通便；皂荚得到麝香，能通窍；诃子得到肉果（肉豆蔻），能止泻；木香得到槟榔，能治疗里急后重；泽泻得到猪苓，能利水；泽泻得到白术，能收湿。这就是药物配伍相得益彰的主要方面。
The *Neijing* (Inner Canon) states: "For conditions without sweating, Guizhi Tang (Cinnamon Twig Decoction) is appropriate," which utilizes Guizhi (Cinnamon Twig) to induce sweating. It further states: "Guizhi should not be taken for conditions without sweating." It also says: "For patients who have sweated excessively, Guizhi Gancao Tang (Cinnamon Twig and Licorice Decoction) is used," which utilizes Guizhi to stop sweating. What is the rationale behind one herb having two different uses? Guizhi is regarded as the "chief of all herbs" and excels at unblocking blood vessels. Therefore, when used to relieve restlessness and induce sweating, it is not because Guizhi directly opens the *couli* (pores/skin interstices) to force sweat out, but because it harmonizes Ying Blood (nutritive blood circulating within the vessels), thereby allowing Wei Qi (defensive qi circulating outside the vessels) to become harmonious. With no place for pathogenic factors to reside, the body naturally sweats, leading to recovery. When Guizhi is used after excessive sweating, it is not because Guizhi directly closes the *couli* to stop sweating, but because it harmonizes Ying and Wei, allowing pathogens to exit with the sweat; once the pathogens are eliminated, sweating ceases naturally. Ignorant practitioners fail to understand this dual function of stopping and inducing sweating. They indiscriminately apply Guizhi to every patient. Unaware that while it yields miraculous results for Taiyang Wind Strike (Wind-Strike Syndrome of the Taiyang Channel) with spontaneous sweating, or Zhongfeng (Wind Stroke/Attack) with spontaneous sweating, its use in Taiyang Cold Damage (Cold-Damage Syndrome of the Taiyang Channel) without sweating—where there is no cold in the bone marrow—is extremely harmful. Thus, Zhang Zhongjing stated: "Do not take Guizhi for conditions without sweating"; and again, "If Guizhi Tang is ingested by a person with Yang Excess, death will ensue." This refers to such cases.
Mahuang (Ephedrae Herba) combined with Guizhi induces sweating; Shaoyao (Paeoniae Radix) combined with Guizhi stops sweating; Renshen (Ginseng Radix) combined with Baizhu (Atractylodis Macrocephalae Rhizoma) stops deficiency sweating; Fangfeng (Saposhnikoviae Radix) combined with Qianghuo (Notopterygii Rhizoma et Radix) treats various wind pathogens; Cangzhu (Atractylodis Rhizoma) combined with Qianghuo alleviates body pain. Chaihu (Bupleuri Radix) combined with Huangqin (Scutellariae Radix) treats heat syndromes; Fuzi (Aconiti Lateralis Radix Praeparata) combined with Ganjiang (Zingiberis Rhizoma) treats cold syndromes; Qianghuo combined with Chuanxiong (Ligustici Chuanxiong Rhizoma) relieves headache; Chuanxiong combined with Tianma (Gastrodiae Rhizoma) relieves dizziness; Gegen (Puerariae Lobatae Radix) combined with Tianhuafen (Trichosanthis Radix) relieves Xiao Ke (Wasting-Thirst); Shigao (Gypsum Fibrosum) combined with Zhimu (Anemarrhenae Rhizoma) relieves thirst; Xiangru (Elsholtziae Herba) combined with Bian Dou (Dolichoris Semen) dispels summerheat; Huangqin combined with Lianqiao (Forsythiae Fructus) clears toxicity; Sangbai Pi (Mori Cortex) combined with Suzi (Perillae Fructus) relieves wheezing; Xingren (Armeniacae Semen Amarum) combined with Wuweizi (Schisandrae Fructus) relieves cough; Dingxiang (Caryophylli Flos) combined with Shidi (Kaki Calyx) and Ganjiang relieves hiccups; Ganjiang combined with Banxia (Pinelliae Rhizoma) relieves vomiting; Banxia combined with Jiangzhi (Zingiberis Juice) resolves phlegm; Beimu (Fritillariae Bulbus) combined with Gualou (Trichosanthis Fructus) resolves congealed phlegm; Jiegeng (Platycodonis Radix) combined with Shengma (Cimicifugae Rhizoma) lifts Qi and Blood; Zhishi (Aurantii Fructus Immaturus) combined with Huanglian (Coptidis Rhizoma) eliminates epigastric fullness; Zhike (Aurantii Fructus) combined with Jiegeng broadens the chest; Zhimu and Huangbai (Phellodendri Cortex) combined with Zhizi (Gardeniae Fructus) descends fire; Douchi (Sojae Semen Preparatum) combined with Zhizi treats Ao Nu (restlessness and vexation); Chen Sha (Cinnabar) combined with Suanzaoren (Ziziphi Spinosae Semen) calms the spirit; Baizhu combined with Huangqin stabilizes pregnancy; Chenpi (Citri Reticulatae Pericarpium) combined with Baizhu tonifies the Spleen; Renshen combined with Wuweizi and Maidong (Ophiopogonis Radix) generates Kidney Water; Cangzhu combined with Xiangfu (Cyperi Rhizoma) opens depression; Houpo (Magnoliae Officinalis Cortex) combined with Fupi (Tangerine Peel/Atractylodis Fruit) reduces distension; Caoguo (Tsaoko Fructus) combined with Shanzha (Crataegi Fructus) resolves meat stagnation; Shenqu (Massa Medicata Fermentata) combined with Maiya (Hordei Fructus Germinatus) aids digestion; Wumei (Mume Fructus) combined with Gegen resolves alcohol intoxication; Sharen (Amomi Fructus) combined with Zhike regulates the Middle Jiao; Muxiang (Aucklandiae Radix) combined with Jiangzhi disperses Qi; Wuyao (Linderae Radix) combined with Xiangfu smooths Qi; Shaoyao combined with Gancao (Glycyrrhizae Radix et Rhizoma) treats abdominal pain due to deficiency; Wuzhuyu (Evodiae Fructus) combined with Liangjiang (Alpiniae Officinarum Rhizoma) treats abdominal pain due to cold; Ruxiang (Olibanum) combined with Moyao (Myrrha) greatly alleviates various pains; Jiezi (Sinapis Semen) combined with Qingpi (Citri Reticulatae Pericarpium Viride) treats hypochondriac pain; Huangqi (Astragali Radix) combined with Da Fuzi tonifies Yang; Zhimu and Huangbai combined with Danggui (Angelicae Sinensis Radix) tonifies Yin; Danggui combined with Shengdi (Rehmanniae Radix) generates Blood; Ou Zhi (Nelumbinis Rhizomatis Jus) mixed with Jing Mo (Ink Stick) stops bleeding; Honghua (Carthami Flos) combined with Danggui invigorates Blood; Guiwei (Angelicae Sinensis Radix Caudex) combined with Taoren (Persicae Semen) breaks up Blood stasis; Dahuang (Rhei Radix et Rhizoma) combined with Mangxiao (Natrii Sulfas) moistens and purges; Zaojiao (Gleditsiae Spina) combined with Shexiang (Moschus) opens orifices; Hezi (Terminaliae Fructus) combined with Rouguo (Myristicae Semen) stops diarrhea; Muxiang combined with Binglang (Arecae Semen) treats tenesmus; Zexie (Alismatis Rhizoma) combined with Zhuling (Polyporus) promotes urination; Zexie combined with Baizhu absorbs dampness. These are the major principles of synergistic herbal compatibility.