泽泻，味甘、酸、微咸，气寒，沉而降，阴中微阳，无毒。入太阳、少阳足经，能入肾。
长
于利水，去阴汗，利小便如神，除湿去渴之仙丹也。
或问泽泻，既是利水消湿之物，宜乎水去湿干，津液自少，胡为反能止渴？岂知泽泻不
独利
水消湿，原善滋阴。如肾中有水湿之气，乃所食水谷不化精而化火，此火非命门之真火，乃
湿热之邪火。邪火不去，则真火不生，真火不生，乃真水不生也。泽泻善泻肾中邪火，泻邪
火，即所以补真水也。苟非补肾火，六味丸中，仲景夫子何以用泽泻耶？夫肾有补无泻，泽
泻补肾，非泻肾，断断无差。不然，何以泻水而口不渴，非泻邪水耶？所以生真水之明验乎
。所以五苓散利膀胱，而津液自润也。
或曰泽泻泻中有补，敬闻命矣，然所泻者水而非火，吾子之谓是泻火，不亦异乎？盖泻
火而
不泻水，是有说焉。膀胱者，太阳之腑也，原属火，不属水。膀胱之水不能下通，本于寒者
少，由于热者多。盖膀胱无火乃水闭，有火又水闭也。泽泻用之于五苓散中，虽泻水，实泻
火也，因其为泻火之味，所以用之出奇。不然，二苓、白术泻水有余，又何必借重泽泻乎。
此泻火之确有至理，人未之思耳。
或问泽泻利多补少，而子必曰补，想因仲景张公用之于六味丸中，故曰泽泻利中有补。
不独
六味丸中为然，即五苓散中用之，何独不然，凡小便不利之人，未有口不渴者，一利小便而
口渴解。五苓散，利小便也。利小便口渴解者，口中生津液也。五苓利小便之水，去则无水
以润口，宜其渴矣，乃不渴，而反生津液，非利中有补之明验乎？且小便之所以不利者，以
膀胱之有邪火。膀胱有火，乃热干津液而口渴。泽泻在五苓散中，逐邪火而存真水，火去乃
水自升，水升乃津液自润，津液润，而灌注于肾宫。谁谓泽泻有泻而无补乎。
或问泽泻用于六味丸中，乃泻中有补，不识用于八味丸中何意？曰∶有深意也。夫肾中
无火
，故用八味地黄丸，于水中补火也。然而火性炎上，不用药以引其下行，乃龙雷之火未必不
随火而沸腾。而用下行之药，但有泻无补，又恐补火，而火仍随水而下泄，又复徒然。使下
行，但有补无泻，又恐补火，而火不随水而下泄，乃补火大旺，必有强阳不倒之虞。妙在泽
泻性既利水，而泻中又复有补，引火下行，泻火之有余，而不损火之不足，辅桂、附以成其
既济之功，谁谓仲景公用泽泻于八味丸中，竟漫无妙义哉。
或问泽泻举世皆以为泻，先生独言泻中有补，且各尽宣其异义，不识八味、六味、五苓之外
，更有何说以广鄙见乎？夫泽泻之义，于三方可悟其微，三方最未尽其妙。泽泻不特泻火之
有余，而且泻水之有余；不特不损火之不足，而且不损水之不足。此泻中有补，前文尽宣。
然而，功不止此。泽泻更能入于水之中，以补火之不足；入于火之中，以泻水之有余。虚寒
之人，夜多遗溺，此火之不足也，势必用益智仁、山茱萸、五味子之类，补以收涩其遗矣。
然徒用酸收之味，不加咸甘之品于其中，乃愈涩而愈遗，泽泻正咸甘之味也。入于益智、
山茱萸、五味子之内，遗溺顿痊。若非利中补火，不更助其遗乎？虚热之人，口必大渴，此
水之不足也，势必用元参、生地黄、沙参、地骨皮、甘菊之类泻火，滋润其渴矣。然徒用苦
寒之味，不加甘咸之品于其中，乃愈止而愈渴。泽泻正甘咸之味也，入之于元参、生地、沙
参、地骨皮、菊花之内，口渴自愈。若非利中补水，不益增其渴乎？此泽泻之微义又如此矣
。
或疑泽泻有功有过，但言其功，而不言其过，恐非持论之平。不知泽泻利水，单用乃有
功有
过，共用乃少过多功。盖单用可以泻水盛之人，不可以泻水虚之子，泻水盛乃有功，泻水虚
乃有过也。共用宜于补剂，不宜于攻剂，补虚乃多功，攻实乃少过也。有过有功，是人之不
善用也，与泽泻何过哉。
或问扁鹊公云多服泽泻，病患服是泽泻，过于利水，非补阴之药矣？此非扁鹊公之言，
乃后
人记而传之者也。泽泻用之六味、八味诸肾药中，但补而无泻，多服、久服，正得大益，又
安能损目哉。惟肾气乏绝，阳衰流精，肾气不固，精滑目痛，不可单服泽泻，以虚其虚，若
入于群补肾药中，又正无害也。
泽泻，味甘、酸、微咸，气性寒凉，药势沉降，属于阴中略带阳性的药物，无毒。它归属于足太阳膀胱经和足少阳胆经，并能入肾经。
泽泻擅长利水渗湿，消除阴部汗出，通利小便效果神奇，是祛除湿邪、解除口渴的仙丹。
有人问：泽泻既然是利水消湿的药物，按理说水去湿除后，津液自然会减少，为什么反而能止渴呢？要知道泽泻不仅利水消湿，原本就善于滋阴。如果肾中有水湿之气，那是由于所食的水谷不能化为精微而化成了火，这火不是命门（肾间动气，人体生命活动的原动力）的真火，而是湿热之邪火。如果不祛除邪火，真火就无法生发；真火不生发，真水也就无法生成。泽泻善于泻除肾中的邪火，泻除邪火，就是补益真水的方法。如果不是为了补肾中之火，张仲景夫子在六味地黄丸中怎么会使用泽泻呢？肾脏只有补法没有泻法，泽泻补肾，并非泻肾，这是绝对正确的。否则，为什么通过泻水反而使口不渴呢？这不是因为泻除了邪水吗？这正是生发真水的明显证据。所以五苓散能通利膀胱，津液自然滋润。
有人说：泽泻是泻中有补，我敬领教诲了，但您所说是泻火而非泻水，这与通常认为它主要泻水不同，难道不奇怪吗？其实，泻火而不单纯泻水，是有道理的。膀胱，是太阳之腑，原本属火，不属水。膀胱之水不能向下通畅，由寒引起的少，由热引起的多。可以说，膀胱如果没有火，水就会闭塞；有火（邪火），水也会闭塞。泽泻用在五苓散中，虽然看似泻水，实际上是泻火，因为它具有泻火的特性，所以使用它能出奇效。否则，茯苓、猪苓和白术泻水已经足够，又何必倚重泽泻呢？这是泻火确有至理之处，只是人们未曾深思罢了。
有人问：泽泻利多补少，而您一定说它有补益作用，想必是因为张仲景公在六味地黄丸中使用它，所以说泽泻利中有补。不仅在六味地黄丸中是这样，在五苓散中使用它，为什么就不是这样呢？凡是小便不利的人，没有口不渴的，一旦利小便，口渴就解除了。五苓散的作用是利小便。利小便后口渴解除，是因为口中生津液了。五苓散利去小便之水，如果水去了没有水来滋润口腔，理应口渴，但却不渴，反而生津液，这不是利中有补的明显证据吗？而且小便之所以不利，是因为膀胱中有邪火。膀胱有火，就会灼干津液导致口渴。泽泻在五苓散中，驱逐邪火而保存真水，火去除则水自然上升，水上升则津液自然滋润，津液滋润后，灌注于肾宫。谁说泽泻只有泻而没有补呢？
有人问：泽泻用于六味地黄丸中，是泻中有补，不知道用于八味地黄丸（金匮肾气丸）中是什么意思？回答说：其中有深意。肾中没有火，所以用八味地黄丸，在水中补火。然而火性炎上，如果不用药引导其下行，龙雷之火（相火）未必不会随着火势沸腾而上冲。如果使用下行的药，只有泻没有补，又担心补火时，火仍随水而下泄，那就白费功夫了。如果下行药只有补没有泻，又担心补火时，火不随水而下泄，导致补火大旺，必然有强阳不倒（阳痿或性功能亢进异常）的忧虑。妙在泽泻性既利水，而在泻中又有补，能引火下行，泻火之有余，而不损伤火之不足，辅助肉桂、附子完成水火既济的功效。谁说张仲景公在八味地黄丸中使用泽泻，竟然毫无妙义呢？
有人问：举世都认为泽泻是泻药，唯独先生您说泻中有补，并且各自阐发不同的见解，不知道除了八味地黄丸、六味地黄丸、五苓散之外，还有什么说法可以开阔我的见识呢？泽泻的道理，可以从这三方中领悟其微妙，但这三方还没有完全展现它的奥妙。泽泻不仅泻火之有余，而且泻水之有余；不仅不损火之不足，而且不损水之不足。这种泻中有补的道理，前文已充分阐述。然而，功效不止于此。泽泻更能进入水中以补火之不足；进入火中以泻水之有余。虚寒之人，夜间多遗尿，这是火之不足，势必使用益智仁、山茱萸、五味子等药物，通过收敛固涩来治疗遗尿。但如果只用酸收的药物，不在其中加入咸甘之品，反而会越涩越遗，泽泻正是咸甘之味。加入益智仁、山茱萸、五味子之中，遗尿立刻痊愈。如果不是利中补火，岂不是更助长遗尿吗？虚热之人，口中必定大渴，这是水之不足，势必使用玄参、生地黄、沙参、地骨皮、甘菊等药物泻火，滋润以解渴。但如果只用苦寒的药物，不在其中加入甘咸之品，反而会越止渴越渴。泽泻正是甘咸之味，加入玄参、生地、沙参、地骨皮、菊花之中，口渴自愈。如果不是利中补水，岂不是更增加口渴吗？泽泻的微妙道理又是如此。
有人怀疑泽泻有功有过，只说它的功效，而不说它的过失，恐怕不是持平的论断。不知道泽泻利水，单用时才有功有过，配伍使用时则是少过而多功。单用可以泻水盛之人，不可以泻水虚之人，泻水盛是有功，泻水虚是有过。配伍使用宜于补剂，不宜于攻剂，补虚是多功，攻实是少过。有过有功，是人不善于使用它，与泽泻有什么过错呢？
有人问：扁鹊公说多服泽泻，病患服用这种泽泻，过于利水，就不是补阴的药了？这不是扁鹊公的话，是后人记录并流传下来的。泽泻用在六味地黄丸、八味地黄丸等各种补肾药中，只补无泻，多服、久服，正能得到大益处，又怎么能损害眼睛呢？只有当肾气乏绝，阳衰流精，肾气不固，精滑目痛时，不可单服泽泻，以免使其更虚，若加入群补肾药中，又正好无害。
Ze Xie (Alisma Rhizome), with a sweet, sour, and slightly salty taste, is cold in nature. It sinks and descends, belonging to Yin with a slight Yang quality, and is non-toxic. It enters the Foot-Taiyang Bladder Meridian and Foot-Shaoyang Gallbladder Meridian, and can also enter the Kidney.
Ze Xie excels at promoting urination and draining dampness, eliminating sweating in the yin region, and facilitating urination with miraculous effect; it is a divine elixir for removing dampness and quenching thirst.
One might ask: Since Ze Xie is a substance that promotes urination and eliminates dampness, logically, as water and dampness leave, body fluids should naturally decrease. Why does it instead quench thirst? One must understand that Ze Xie not only promotes urination and eliminates dampness but is originally good at nourishing Yin. If there is damp-heat qi in the Kidney, it arises because ingested food and water fail to transform into essence and instead transform into fire. This fire is not the true fire of the Mingmen (Gate of Vitality, the source of original Qi), but rather the evil fire of damp-heat. If this evil fire is not removed, the true fire cannot arise; if the true fire does not arise, the true Water (Yin) cannot be generated. Ze Xie is adept at draining the evil fire from the Kidney; draining the evil fire is precisely how one tonifies the true Water. If it were not for tonifying the fire within the Kidney, why would Master Zhang Zhongjing use Ze Xie in Liuwei Dihuang Wan (Six-Ingredient Pill with Rehmannia)? The Kidney has only tonification methods, no purgation methods; Ze Xie tonifies the Kidney, it does not purge the Kidney, which is absolutely correct. Otherwise, why would purging water result in no thirst? Is this not because it purges evil water? This is clear evidence of generating true Water. Thus, Wuling San (Five-Ingredient Powder with Poria) facilitates the Bladder, and body fluids become naturally moistened.
Someone might say: Ze Xie is purging while simultaneously tonifying; I respectfully accept this teaching. However, what is purged is water, not fire. Your assertion that it purges fire seems unusual. In fact, purging fire without merely purging water has its rationale. The Bladder is the Fu organ of Taiyang; originally, it belongs to Fire, not Water. The inability of water in the Bladder to flow downward is rarely due to Cold but mostly due to Heat. Essentially, if the Bladder lacks Fire, water becomes obstructed; if it has Fire (evil fire), water also becomes obstructed. When Ze Xie is used in Wuling San, although it appears to drain water, it actually drains fire. Because it possesses the property of draining fire, its use yields remarkable results. Otherwise, Lingzhi (Poria) and Baizhu (Atractylodes Macrocephala Rhizome) are sufficient for draining water; why rely heavily on Ze Xie? This principle of draining fire is sound, yet people have not pondered it.
One might ask: Ze Xie has more purgative than tonifying effects, yet you insist it has tonifying properties. I assume this is because Zhang Zhongjing used it in Liuwei Dihuang Wan, hence stating that Ze Xie tonifies while purging. But this applies not only to Liuwei Dihuang Wan. Why not in Wuling San? In all cases of difficult urination, there is no instance of no thirst. Once urination is facilitated, thirst resolves. Wuling San facilitates urination. The resolution of thirst after facilitating urition indicates the generation of body fluids in the mouth. Wuling San drains water from urination; if water leaves and nothing remains to moisten the mouth, thirst should ensue. Yet, there is no thirst, and body fluids are generated. Is this not clear evidence of tonification within purgation? Moreover, the reason for difficult urination is the presence of evil fire in the Bladder. Fire in the Bladder scorches and dries body fluids, causing thirst. In Wuling San, Ze Xie drives out evil fire and preserves true Water. With fire gone, Water rises naturally; with Water rising, body fluids become moistened. These fluids then irrigate the Palace of the Kidney. Who says Ze Xie only purges and does not tonify?
One might ask: Ze Xie is used in Liuwei Dihuang Wan for purging with tonification. What is the intention when used in Shenzi Wan (Eight-Ingredient Pill with Rehmannia, also known as Jin Gui Shen Qi Wan)? The answer is: There is profound meaning. When there is no Fire in the Kidney, Shenzi Wan is used to tonify Fire within Water. However, Fire tends to flare upward. Without medicine to guide it downward, the Dragon-Lei Fire (Ministerial Fire) may well surge upwards with the heat. If using descending medicines that only purge and do not tonify, one fears that during Fire tonification, the Fire will still leak downwards with the Water, rendering the effort futile. If descending medicines only tonify and do not purge, one fears that during Fire tonification, the Fire will not descend with the Water, leading to excessive Fire tonification and potentially causing persistent erection (strong yang不倒). The brilliance lies in Ze Xie’s nature: it promotes urination, and within its purgative action, it contains tonification. It guides Fire downward, reduces excess Fire, and does not damage deficient Fire. It assists Rougui (Cinnamon Bark) and Fuzi (Prepared Aconite Root) to achieve the state of Mutual Interaction between Heart and Kidney (Water-Fire Ji Ji). Who says Zhang Zhongjing’s use of Ze Xie in Shenzi Wan lacks profound significance?
One might ask: The world generally considers Ze Xie a purgative, yet you alone claim it tonifies while purging, and each expounds different views. Besides Shenzi Wan, Liuwei Dihuang Wan, and Wuling San, are there other explanations to broaden my understanding? The essence of Ze Xie can be understood through these three formulas, but they do not fully reveal its wonders. Ze Xie not only drains excess Fire but also drains excess Water; it not only preserves deficient Fire but also preserves deficient Water. This concept of tonification within purgation was fully explained earlier. However, its functions extend beyond this. Ze Xie can enter Water to tonify deficient Fire; it can enter Fire to drain excess Water. For individuals with deficiency-cold who suffer from frequent nocturnal enuresis, this indicates deficient Fire. One would inevitably use herbs like Yizhiren (Biotae Semen), Shanzhuyu (Corni Fructus), and Wuweizi (Schisandrae Fructus) to astringe and stop enuresis. However, using only sour-astringent substances without adding salty-sweet items will lead to increased retention and continued leakage. Ze Xie is salty and sweet. When added to Yizhiren, Shanzhuyu, and Wuweizi, enuresis is instantly cured. If it did not tonify Fire within its purgative action, would it not exacerbate enuresis? For individuals with deficiency-heat who suffer from severe thirst, this indicates deficient Water. One would inevitably use herbs like Xuanshen (Scrophulariae Radix), Shengdihuang (Rehmanniae Radix), Shashen (Glehniae Radix), Digupi (Lycii Cortex), and Ganju (Chrysanthemi Flos) to drain Fire and moisten to relieve thirst. However, using only bitter-cold substances without adding sweet-salty items will lead to increased dryness despite attempts to stop thirst. Ze Xie is sweet and salty. When added to Xuanshen, Shengdihuang, Shashen, Digupi, and Juhua, thirst heals itself. If it did not tonify Water within its purgative action, would it not increase thirst? Thus, the subtle meaning of Ze Xie is as follows.
One might suspect that Ze Xie has both merits and faults, but discussing only its merits without mentioning its faults is not a balanced argument. In reality, when Ze Xie is used alone for promoting urination, it has both merits and faults; when used in combination, it has few faults and many merits. Used alone, it can treat those with excess Water but should not be used for those with deficient Water. Draining excess Water is meritorious; draining deficient Water is faulty. When combined, it is suitable for tonic prescriptions, not for attack/excess-clearing prescriptions. Tonifying deficiency yields many merits; attacking excess yields few faults. Having faults and merits is due to improper human usage, not a fault of Ze Xie itself.
One might ask: Bian Que stated that taking large amounts of Ze Xie causes patients to take too much diuretic effect, implying it is not a Yin-tonifying drug? This is not Bian Que’s words, but rather recorded and transmitted by later generations. When Ze Xie is used in Liuwei Dihuang Wan, Shenzi Wan, and other Kidney-tonifying formulas, where it tonifies without purging, long-term and heavy use brings great benefit and certainly does not harm the eyes. Only in cases of exhausted Kidney Qi, Yang decline with seminal emission, insecure Kidney Qi, seminal slipperiness, and eye pain, should Ze Xie not be taken alone, as this would further deplete deficiency. However, if included among a group of Kidney-tonifying herbs, it is perfectly harmless.