肿胀者。水病也。气病也。失血家往往水肿气肿。抑又何哉。盖以血之与气。水之与火。互相倚伏。是二是一。
吾于水火血气论。及调经去痰诸条。已言之。兹复不惮烦劳曰。气即水也。血中有气。即有水。故肌肉中有
汗。口鼻中有津。胞中有水。是水与血。原并行不悖。失血家。其血既病。则亦累及于水。水蓄胞中。则为尿结。
水淫脾胃。则为胀满。水浸皮肤。则为水肿。治法。皮肤水肿者。宜从肺治之。以肺主皮毛故也。肺为水之上
原。肺气行则水行。宜泻白散。加杏仁桔梗紫苏茯苓。五皮饮亦治之。大腹胀满者。宜从脾治之。补土利水。
则水行而土敦。胃苓汤主之。六君子汤。加苡仁防己亦主之。胞中水结。小腹胀满者。五苓散治之。猪苓汤
亦治之。诸水又皆肾之所主。肾气化。则上下内外之水俱化。宜六味地黄丸。
以上所举之方。皆平剂也。医者又须审别阴阳。随加寒热之品。乃能奏效。审其口渴溺赤。喜凉脉数者。为
阳水。则知柏芩连山栀石膏天冬麦冬。可加入。审其口和溺清。喜热脉濡。为阴水。则桂附干姜吴萸细辛。
可加入。失血家阳水居多。阴水最少。医者须临时细审。
又有瘀血流注。亦发肿胀者。乃血变成水之证。此如女子胞水之变血。男子胞血之变精。疮科血积之变
脓也。血既变水。即从水治之。宜照上所举诸方。分寒热加减。再加琥珀三七当归川芎桃奴蒲黄。以兼理
其血。斯水与血源流俱治矣。古称妇人错经而肿者。为水化为血。名曰水分。经水闭绝而肿者。为血化为
水。名曰血分。其实治法。总宜从水治之。方证加减。举不外此也。观于妇人水分血分之说。则知血家所以
多肿胀者。亦是水分血分之病也。此与杂证水肿有别。勿妄用舟车丸。及消水圣愈汤等。另详血臌门。
肿胀，属于水液代谢失常的病证，也属于气机失调的病证。失血的患者往往会出现水肿或气肿，这又是为什么呢？这是因为血与气、水与火，相互依存、相互转化，看似两种事物，实则本质同一。
我在《水火血气论》以及调经、去痰等章节中已经论述过这一点。这里再不厌其烦地说明：气就是水，血中含有气，也就含有水。所以肌肉中有汗，口鼻中有津液，胞宫（子宫/膀胱）中有水液，这说明水与血原本是并行不悖的。失血患者，既然血液已经生病，那么也会波及到水液。水液蓄积在胞中，就会形成尿结（小便不通）；水液泛滥于脾胃，就会形成胀满；水液浸渍皮肤，就会形成水肿。
治疗方法上：对于皮肤水肿者，应当从肺脏治疗，因为肺主皮毛的缘故。肺为水之上源，肺气运行则水液随之运行，宜用泻白散（清泻肺热之方），加杏仁、桔梗、紫苏、茯苓。五皮饮（利水消肿之方）也可以治疗此症。大腹胀满者，应当从脾脏治疗，通过补益脾气以利水湿，这样水湿得行而土气敦厚，以胃苓汤（健脾燥湿利水之方）为主治方剂。六君子汤（益气健脾化痰之方），加薏苡仁、防己也可以主治。胞中水液结聚，小腹胀满者，以五苓散（利水渗湿之方）治疗，猪苓汤（利水养阴之方）也可以治疗。各种水液病证又都由肾脏所主，肾气化功能正常，则上下内外的水液都能被气化代谢，宜用六味地黄丸（滋补肾阴之方）。
以上所列出的方剂，都属于平和的药剂。医生还必须辨别阴阳，根据情况加入寒性或热性的药物，才能奏效。如果审察患者口渴、小便赤红、喜凉、脉数，属于阳水，则可以加入知母、黄柏、黄芩、黄连、山栀、石膏、天冬、麦冬等药。如果审察患者口中和润、小便清长、喜热、脉濡缓，属于阴水，则可以加入肉桂、附子、干姜、吴茱萸、细辛等药。失血患者多为阳水，阴水最少。医生必须临证时仔细审察。
又有瘀血流注体内，也会引发肿胀的，这是血转化为水的证候。这就像女子胞中的血变为水，男子精室中的血变为精，外科疮疡中血积化为脓一样。血既然变成了水，就应当按照治水的方法治疗，宜参照上述所列诸方，分寒热进行加减，再加入琥珀、三七、当归、川芎、桃奴、蒲黄，以兼顾调理血液。这样水和血的源头及流变都得到治理了。古人称妇人因月经错乱而肿胀的，称为“水化为血”，名叫“水分”；因经水闭绝而肿胀的，称为“血化为水”，名叫“血分”。其实治疗方法，总宜从治水入手，方证的加减，都不超出这个范围。观察妇人“水分”、“血分”的说法，就知道失血患者之所以多出现肿胀，也是水分和血分的病证。这与普通杂病的水肿不同，不要妄用舟车丸（峻下逐水之方）及消水圣愈汤等猛药，详见《血臌门》。
Swelling is a disorder of water metabolism and also a disorder of Qi. Patients who have suffered blood loss often develop edema or Qi distension. Why is this? It is because Blood and Qi, Water and Fire, rely on each other and transform into one another; though they appear as two distinct entities, their essence is one.
I have discussed this in the "Treatise on Water, Fire, Blood, and Qi" and in sections regarding regulating menstruation and removing phlegm. Here, I will not spare the effort to explain further: Qi is essentially Water. Since Blood contains Qi, it also contains Water. Therefore, sweat exists in muscles, fluids exist in the mouth and nose, and water exists in the Bao (uterus/bladder). This demonstrates that Water and Blood originally flow together without contradiction. In patients with blood loss, since the Blood is diseased, it inevitably affects the Water. If Water accumulates in the Bao, it results in urinary retention (Jie Lin); if Water overflows into the Spleen and Stomach, it causes abdominal distension; if Water infiltrates the skin, it causes edema.
Regarding treatment methods: For edema of the skin, treatment should target the Lung, because the Lung governs the skin and hair. The Lung is the upper source of Water; when Lung Qi moves, Water moves. One should use Xie Bai San (White-Draining Powder) with added Xing Ren (Apricot Seed), Jie Geng (Platycodon Root), Zi Su (Perilla Leaf), and Fu Ling (Poria). Wu Pi Yin (Five-Peel Decoction) can also treat this condition. For severe abdominal distension, treatment should target the Spleen. By tonifying Earth (Spleen) to promote water drainage, the Water moves and the Earth becomes firm. Wei Ling Tang (Stomach-Calm Decoction) is the primary formula. Liu Jun Zi Tang (Six-Gentleman Decoction) with added Yi Yi Ren (Coix Seed) and Fang Ji (Stephania Root) can also be used. For water accumulation in the Bao causing lower abdominal distension, Wu Ling San (Five-Ingredient Powder with Poria) is indicated, and Zhu Ling Tang (Polyporus Decoction) can also be used. All water disorders are primarily governed by the Kidney. When Kidney Qi transforms properly, water throughout the body, inside and out, is metabolized. Liu Wei Di Huang Wan (Six-Ingredient Pill with Rehmannia) is appropriate.
The formulas listed above are all mild agents. Physicians must distinguish between Yin and Yang and add cold or hot herbs accordingly to achieve efficacy. If the patient presents with thirst, dark urine, preference for coolness, and a rapid pulse, it is classified as Yang Water. In such cases, Zhi Mu (Anemarrhena Rhizome), Huang Bo (Phellodendron Bark), Huang Qin (Scutellaria Root), Huang Lian (Coptis Rhizome), Shan Zhi (Gardenia Fruit), Shi Gao (Gypsum), Tian Dong (Asparagus Tuber), and Mai Dong (Ophiopogon Tuber) may be added. If the patient has a normal taste in the mouth, clear urine, preference for warmth, and a soft pulse, it is classified as Yin Water. In such cases, Rou Gui (Cinnamon Bark), Fu Zi (Aconite Root), Gan Jiang (Dried Ginger), Wu Zhu Yu (Evodia Fruit), and Xi Xin (Asarum Root) may be added. Patients with blood loss predominantly suffer from Yang Water, while Yin Water is rare. Physicians must carefully examine the case at hand.
Furthermore, stagnant Blood flowing into collaterals can also cause swelling; this is a syndrome where Blood transforms into Water. This is analogous to Blood transforming into Water in the female Bao, Blood transforming into Essence in the male Jing Shi, or Blood stasis transforming into Pus in surgical sores. Since Blood has transformed into Water, it should be treated according to water-drainage principles. One should refer to the aforementioned formulas, adjusting for cold or heat, and additionally add Hu Po (Amber), San Qi (Notoginseng Root), Dang Gui (Angelica Sinensis), Chuan Xiong (Ligusticum Rhizome), Tao Nu (Withered Peach Bud), and Pu Huang (Typha Pollen) to simultaneously regulate Blood. In this way, both the source and flow of Water and Blood are addressed. Ancient texts state that women who swell due to irregular menstruation suffer from "Water transforming into Blood," termed "Shui Fen" (Water Partition); those who swell due to amenorrhea suffer from "Blood transforming into Water," termed "Xue Fen" (Blood Partition). In reality, the treatment method always prioritizes treating the Water aspect. Formula adjustments do not exceed these principles. Observing the concepts of Shui Fen and Xue Fen in women, we understand that the reason blood-loss patients often experience swelling is also a disease of Shui Fen and Xue Fen. This differs from edema in miscellaneous diseases; one should not recklessly use Zhou Che Wan (Boat Cart Pill) or Xiao Shui Sheng Yu Tang (Water-Draining Supreme Replenishment Decoction), etc. See the section on "Blood Distension" for details.