五苓、猪苓，并治脉浮，发热，渴而小便不利之症。然五苓则加桂枝、白术，而治太阳
；猪
苓则加滑石、阿胶，而治阳明。盖太阳为开，阳明为阖。太阳为表之表，其受邪也，可以热
发，可以辛散；阳明为表之里，其气难泄，其热易蓄，其发散攻取，自与太阳不同。是以五
苓散加甘辛温药，假阳气以行水；猪苓汤加甘咸寒药，假阴气以利水也。
伤寒下后，心下满而不痛者，为痞，半夏泻心汤主之。盖客邪内陷，既不可从汗泄；而
痞不
实，又不可从下夺。故惟半夏、干姜之辛，能散其结；芩、连之苦，能泄其满。热其所以泄
、散者，虽药之能，而实胃气之使也。此用人参、甘草者，非以下后中伤，故以益气而助其
能耶！
甘草泻心、生姜泻心，虽同为治痞之剂，而生姜泻心意在胃中不和，故加辛温以和胃；
甘草泻心意在下利不止与客气上逆，故不欲人参之增气，而须甘草之安中也。
大黄黄连泻心肠，治伤寒汗下后心下痞，按之濡，其脉关上浮者。成氏云∶此虚热也，
与大
黄、黄连以导其虚热。按成氏所谓虚热者，对燥屎而言也。盖邪热入里，与糟粕相结，则为
实热；不与糟粕相结，则为虚热；非阴虚、阳虚之谓。本方以大黄、黄连为剂，而不用枳、
朴等药者，盖以泄热，非以荡实热也。
五苓散和猪苓汤，都用于治疗脉象浮、发热、口渴且小便不利的症状。然而，五苓散加入了桂枝和白术，用来治疗太阳病（足太阳膀胱经受邪所致的表证）；猪苓汤加入了滑石和阿胶，用来治疗阳明病（足阳明胃经受邪所致的里热证）。这是因为太阳主“开”（宣发），阳明主“阖”（闭藏）。太阳是体表最外层的防御，感受邪气时，可以通过发汗来散热，也可以通过辛温药物发散；阳明位于体表的内部，其气机难以宣泄，热邪容易积聚，因此其发散和攻下的治法，自然与太阳病不同。所以，五苓散加入甘、辛、温性的药物，是借助阳气来推动水液运行；猪苓汤加入甘、咸、寒性的药物，是借助阴气来通利水道。
伤寒病经过泻下治疗后，如果心下部（胃脘部）胀满但不疼痛的，称为痞证（气机阻滞形成的痞塞感），用半夏泻心汤主治。因为外来的邪气内陷，既然不能通过发汗来解除；而痞证并非实邪结聚，又不能通过泻下来攻逐。所以只有半夏、干姜的辛味，能够散开郁结；黄芩、黄连的苦味，能够泄除胀满。之所以能发挥泄热、散结的作用，虽然是药物的功效，但实际上是依靠胃气的运转来实现的。这里使用人参、甘草的原因，难道不是因为泻下后中焦受损，所以用它们来益气并辅助药力吗！
甘草泻心汤和生姜泻心汤，虽然都是治疗痞证的方剂，但生姜泻心汤针对的是胃中不和，所以加入辛温药物以调和胃气；甘草泻心汤针对的是腹泻不止和客气上逆，所以不希望用人参增加气机，而是需要甘草来安定中焦。
大黄黄连泻心汤，用于治疗伤寒经过发汗或泻下后出现的心下痞，按之柔软，脉象关部浮起的症状。成无己说：这是虚热，给予大黄、黄连来引导清除虚热。按成无己所说的“虚热”，是相对于燥屎而言的。邪热进入体内，与糟粕相结合，就形成实热；不与糟粕结合，就称为虚热；这里指的并不是阴虚或阳虚的概念。本方以大黄的、黄连为君药，而不使用枳实、厚朴等药物，是因为目的是泄热，而不是为了荡涤实邪积滞。
Wuling San (Five-Ingredient Powder with Poria) and Zhuling Tang (Polyporus Decoction) both treat symptoms of floating pulse (pulse felt lightly at the surface), fever, thirst, and difficult urination. However, Wuling San adds Guizhi Twig (Cinnamon Twig) and Atractylodis Rhizoma to treat Taiyang disease (disease of the Foot-Taiyang Bladder channel); whereas Zhuling Tang adds Talcum and Eupolyphaga (Silkworm) to treat Yangming disease (disease of the Foot-Yangming Stomach channel). This is because Taiyang governs "opening" (dispersing), while Yangming governs "closing" (conserving). Taiyang is the outermost layer of the exterior; when invaded by pathogens, heat can be released through sweating or dispersed using acrid-warm herbs. Yangming is interior to the exterior; its qi is difficult to vent, and heat easily accumulates. Therefore, its methods of dispersing and purging differ from those for Taiyang. Thus, Wuling San adds sweet, acrid, and warm herbs to borrow the power of Yang Qi to move water; Zhuling Tang adds sweet, salty, and cold herbs to borrow the power of Yin Qi to promote diuresis.
After a Shaoyin disease has been treated with purgatives, if there is fullness in the epigastrium without pain, it is termed Pi syndrome (a sensation of blockage due to qi stagnation), which is primarily treated with Banxia Xiexin Tang (Pinellia Heart-Draining Decoction). Since the invading pathogen has sunk inward, it cannot be resolved through sweating; and since Pi is not a solid accumulation, it cannot be treated with purgation. Therefore, only the acridity of Banxia (Pinellia Rhizome) and Shengjiang (Fresh Ginger Root) can scatter the knot; the bitterness of Huangqin (Scutellaria Root) and Huanglian (Coptis Rhizome) can drain the fullness. The reason these herbs can drain heat and scatter knots, although a function of the drugs, actually relies on the movement of Stomach Qi. Is this why Renshen (Ginseng Root) and Gancao (Licorice Root) are used? Not merely because the middle jiao was injured by purgation, thereby requiring them to tonify Qi and assist efficacy!
Gancao Xiexin Tang (Licorice Heart-Draining Decoction) and Shengjiang Xiexin Tang (Fresh Ginger Heart-Draining Decoction), although both formulas for treating Pi, differ in intent: Shengjiang Xiexin Tang targets disharmony in the Stomach, thus adding acrid-warm herbs to harmonize the Stomach; Gancao Xiexin Tang targets persistent diarrhea and rebellious pathogenic qi, thus avoiding the use of Renshen to prevent increasing Qi, and instead relying on Gancao to stabilize the Middle Jiao.
Dahuang Huanglian Xiexin Tang (Rhubarb and Coptis Heart-Draining Decoction) treats Pi in the epigastrium following sweating or purgation for Shaoyin disease, where palpation reveals softness and the pulse is floating at the Guan position (middle position). Cheng Wuji stated: "This is deficient heat, treated with Dahuang (Rhubarb Root) and Huanglian to guide out the deficient heat." By "deficient heat," Cheng refers to the contrast with dry feces. When pathogenic heat enters the interior and binds with waste matter, it becomes excess heat; when it does not bind with waste matter, it is termed deficient heat; this does not refer to Yin deficiency or Yang deficiency. In this formula, Dahuang and Huanglian are used as the principal ingredients, without Zhi Shi (Immature Bitter Orange) or Houpo (Magnolia Bark), because the purpose is to drain heat, not to purge solid excess accumulation.