（水草）泻膀胱气分湿热
泽泻（专入膀胱肾）。甘淡微寒。能入膀胱气分。以泻肾经火邪。功专利水除湿。故五
苓散用
又治
水蓄烦渴小便不利。或吐或泻。五苓散主之。方用泽泻。故知长于行水。）八味丸用此以泻
肾经湿火。（时珍曰。地黄丸用茯苓泽泻者。乃取其泻膀胱之邪气。非接引也。古人用补药
。必兼泻邪。邪去则补药得力。一辟一阖。此乃玄妙。后人不知此理。专一于补。所以久服
必有偏胜之害矣。汪昂曰。六味丸有熟地之温。丹皮之凉。山药之涩。茯苓之渗。山茱之收
。泽泻之泻。补肾而兼补脾。有补而必有泻。相和相济。以成平补之功。乃平淡之神奇。所
以为古今不易之良方也。即有加减。或加紫河车一具。或五味麦冬杜仲牛膝之类。不过一二
味。极三四味而止。今人或疑泽泻之泻而减之。多拣本草补药。恣意加入。有补无泻。且客
倍于主。责成不专。而六味之功。反退处于虚位。失制方之本意矣。此近世庸师之误也。）
俾其补不偏胜。则补始无碍耳。岂曰泽泻补阴。功同于地黄之列哉？第其湿热不除。则病症
莫测。故有消渴呕吐。痰饮肿胀。香港脚阴汗。尿血泄精种种等症。（病症皆因湿热为害。）用
此甘淡微咸以为渗泄。（精泄安可渗利。因于湿热而成。不得不渗利耳。）则浊气既降。而
清气上行。（故有耳聪目明之功。）所谓一除而百病与之俱除也。但小便过利。则肾水愈虚。
而目必昏。（易老云。泻伏水。去留垢。故明目。小便利。肾气虚。故目昏。）此一定之理耳
。盐水炒。或酒拌。忌铁。
（泽泻）能清除膀胱气分的湿热。
泽泻（专门入膀胱经和肾经）。味甘、淡，性微寒。能够进入膀胱的气分，以清泻肾经的火邪，功效专长于利水除湿。因此五苓散中使用了它。
又用于治疗水液停蓄导致的烦渴、小便不利，或者呕吐或腹泻的情况，用五苓散主治。方剂中使用泽泻，所以知道它擅长行水。（八味丸中使用此药是为了清泻肾经的湿火。）
李时珍说：地黄丸中使用茯苓和泽泻，是借它们来泻除膀胱的邪气，并非为了引导补药进入。古人使用补药时，必定兼用泻邪的药物，邪气去除后补药才能发挥作用，一开一阖，这是其中的玄妙之处。后人不懂这个道理，专一于补益，所以长期服用必然会有偏胜的危害。
汪昂说：六味丸中有熟地黄的温性，牡丹皮的凉性，山药的涩性，茯苓的渗利性，山茱萸的收涩性，泽泻的泻性，补肾的同时兼补脾脏，有补必有泻，相互调和济助，从而达成平补的功效，这是平淡中的神奇之处，所以成为古今不变的良方。即使有加减，或者加入紫河车一个，或者五味子、麦冬、杜仲、牛膝之类，不过一二味，极多三四味就停止了。现在的人怀疑泽泻的泻性而减去它，多选本草中的补药肆意加入，有补无泻，而且客药倍数超过主药，责任不专一，导致六味丸的功效反而退处于虚位，失去了制方的本意。这是近代庸医的错误。
（这样）使得补益不偏胜，那么补益才没有妨碍。怎么能说泽泻补阴，功效与地黄同类呢？只是如果湿热不除去，病症就难以预测，所以有消渴、呕吐、痰饮、肿胀、香港脚（足部湿疹或真菌感染）、阴汗、尿血、泄精等各种症状。（这些病症都是因为湿热为害所致。）使用此药甘淡微咸的性质来进行渗泄。（精泄怎么可以用渗利之法？因为是由于湿热造成的，不得不采用渗利的方法。）这样浊气下降，清气上行。（所以有耳聪目明的功效。）所谓去除一种病因而百病随之消除。但是小便过度通利，则肾水更加虚弱，眼睛必定昏花。（易老说：泻伏留之水，去除积滞污垢，所以明目；小便过多，肾气虚弱，所以目昏。）这是一定的道理。用盐水炒，或用酒拌。忌铁器。
(Cattail Pollen / Zexie) Drains damp-heat from the Qi aspect of the Bladder.
Ze Xie (Zexiae Rhizoma, specifically enters the Bladder and Kidney meridians). Sweet, bland, slightly cold. It can enter the Qi aspect of the Bladder to drain fire pathogens from the Kidney meridian. Its efficacy specializes in promoting urination and removing dampness. Therefore, it is used in Wu Ling San (Five Ingredient Powder with Poria).
It also treats conditions where water accumulation causes irritability and thirst, difficult urination, or vomiting or diarrhea; Wu Ling San is the primary formula. The use of Ze Xie in the formula indicates its proficiency in moving water. (Ba Wei Wan [Eight-Ingredient Pill] uses this herb to drain damp-fire from the Kidney meridian.)
Li Shizhen said: In Di Huang Wan [Rehmannia Pill], Fuling (Poria) and Ze Xie are used to drain pathogenic qi from the Bladder, not to guide tonification. Ancients, when using tonifying medicines, always combined them with draining herbs. Once pathogens are removed, tonics can take effect. One opening and one closing constitutes the profound mystery. Later generations did not understand this principle, focusing solely on tonification, thus long-term use inevitably leads to harm from excessiveness.
Wang Ang said: Liu Wei Di Huang Wan contains the warmth of Shu Di Huang (Prepared Rehmannia Root), the coolness of Mu Dan Pi (Moutan Cortex), astringency of Shan Yao (Dioscorea Rhizome), permeability of Fu Ling (Poria), astringency of Shan Zhu Yu (Cornus Fruit), and draining action of Ze Xie. It tonifies the Kidney while simultaneously tonifying the Spleen. There must be draining accompanying tonification; they harmonize and assist each other to achieve balanced tonification. This is the miracle within simplicity, making it an unchanging excellent prescription since ancient times. Even with modifications, such as adding one Zi He Che (Human Placenta), or a few flavors like Wu Wei Zi (Schisandra Berry), Mai Dong (Ophiopogon Tuber), Du Zhong (Eucommia Bark), or Niu Xi (Achyranthes Root), it rarely exceeds two or three ingredients. Modern people doubt the draining nature of Ze Xie and remove it, arbitrarily adding many tonifying herbs from materia medica. With tonification but no draining, and guest herbs outnumbering host herbs, responsibility is not focused, causing the efficacy of Liu Wei Wan to retreat to a vacant position, losing the original intent of the prescription. This is the error of mediocre physicians in recent times.
(Thus) ensuring tonification does not become excessive allows for safe tonification. How can one say Ze Xie tonifies Yin with efficacy comparable to Di Huang (Rehmannia)? However, if damp-heat is not eliminated, symptoms become unpredictable, leading to conditions such as Xiao Ke (Wasting-Thirst), vomiting, Tan Yin (Phlegm-Fluid retention), swelling, Hong Kong Jiao (Tinea Pedis/Foot Athlete's Foot), Yin Han (Scrotal Sweating), Hematuria, and Jing Xie (Spermatorrhea). (These symptoms are all caused by the harm of damp-heat.) Using this herb's sweet, bland, and slightly salty properties facilitates percolation and drainage. (How can spermatorrhea be treated with diuretics? Because it arises from damp-heat, diuretics are necessarily employed.) Thus, turbid Qi descends, and clear Qi ascends. (Hence, there is the efficacy of clear hearing and bright vision.) It is said that eliminating one cause eliminates hundred diseases. But if urination is excessively profuse, Kidney Water becomes more deficient, and vision will surely dim. (Yi Lao said: Draining hidden water and removing retained filth clarifies the eyes; excessive urination depletes Kidney Qi, causing dim vision.) This is a fixed principle. Stir-fry with salt water, or mix with wine. Avoid iron.