Herb Tuber (块茎 kuài jīng / 块根 kuài gēn)

Ze Xie

Water plantain rhizome · 泽泻

Alisma orientale (Sam.) Juzep. · Rhizoma Alismatis

Also known as: Water plantain, Oriental water plantain, Alisma,

Ze Xie (Water plantain rhizome) plant

Images shown are for educational purposes only

Ze Xie (water plantain rhizome) is a widely used herb that helps the body drain excess fluid through urination. It is commonly found in formulas for water retention, swelling, urinary difficulty, dizziness related to fluid buildup, and high cholesterol. Its cold nature also helps clear unwanted heat from the Kidneys and Bladder.

Category Dampness-draining herbs (利水渗湿药)
Therapeutic focus Urinary Health Fluid Retention and Edema Cholesterol Management Kidney Health

TCM Properties

Temperature

Cold

Taste

Sweet (甘 gān), Bland (淡 dàn)

Channels entered

Kidneys, Urinary Bladder

Parts used

Tuber (块茎 kuài jīng / 块根 kuài gēn)

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What This Herb Does

Every herb has a specific set of actions — here's what Ze Xie does in the body, explained in both everyday and TCM terms

Therapeutic focus

In practical terms, Ze Xie is primarily used to support these areas of health:

Urinary Health Fluid Retention and Edema Cholesterol Management Kidney Health

TCM Actions

In TCM terminology, these are the specific therapeutic actions that Ze Xie performs to restore balance in the body:

Promotes Urination and Drains Dampness Clears Heat Transforms Turbidity and Lowers Lipids Drains Kidney Fire

How these actions work

'Promotes urination and drains Dampness' is the core action of Ze Xie. Its sweet and bland taste gives it a strong ability to leach out accumulated fluid through the urinary tract. This makes it useful whenever water and Dampness accumulate in the body, causing symptoms like reduced urination, swelling, diarrhea from undigested fluids, or dizziness from Phlegm-fluid (a form of congealed Dampness) blocking the clear Yang from rising to the head. A classical teaching notes that Ze Xie "excels at moving water" (其功尤长于行水). It is one of the strongest water-draining herbs available, acting directly on the Kidney and Bladder channels to open the water pathways.

'Drains Heat' refers to Ze Xie's cold nature, which allows it to clear Heat from the lower body, particularly from the Bladder (relieving painful, burning urination) and from the Kidneys (cooling Deficiency Fire). When Kidney Yin is depleted and pathological Heat flares upward, Ze Xie can drain this excess warmth downward and out through the urine. This is why it appears in formulas like Liu Wei Di Huang Wan, where it partners with Yin-nourishing herbs.

'Resolves turbidity and lowers lipids' is a modern extension of Ze Xie's traditional ability to drain turbid Dampness. In contemporary practice it is used for high cholesterol and triglycerides, conditions understood in TCM as turbid Phlegm-Dampness accumulating in the blood vessels. Modern pharmacological research has confirmed lipid-lowering and anti-atherosclerotic effects from its triterpenoid compounds.

'Drains Kidney Deficiency Fire' means that when the Kidneys lack sufficient Yin fluid, a type of pathological Heat (called "Ministerial Fire" or xiāng huǒ) can flare upward. Ze Xie can drain this Heat downward, creating space for true Yin to be restored. This is a subtle action: by removing the pathological fire, the body's genuine water can regenerate.

Patterns Addressed

In TCM, symptoms cluster into recognizable patterns of disharmony. Ze Xie is used to help correct these specific patterns.

Why Ze Xie addresses this pattern

When the Spleen fails to transform and transport fluids, or the Kidneys and Bladder cannot properly regulate water metabolism, fluid accumulates internally and overflows into the tissues. Ze Xie directly enters the Kidney and Bladder channels and uses its bland, seeping nature to open the water pathways and promote urination. Its sweet taste gently supports fluid transformation without harsh purgation. By draining accumulated water downward and out, it resolves edema, restores normal urination, and addresses the root fluid stagnation behind this pattern.

A practitioner would look for one or more of these signs

Peripheral Edema

Swelling of the limbs and face from fluid retention

Oliguria

Reduced or scanty urination

Diarrhea

Watery diarrhea from undigested fluids (water-grain separation failure)

Abdominal Pain

Distension and fullness in the abdomen

Commonly Used For

These are conditions where Ze Xie is frequently used — but only when they arise from the specific patterns it addresses, not in all cases

Arises from: Water-Dampness Overflow

TCM Interpretation

In TCM, edema is understood as a failure of the body's water metabolism system. Three organ systems are primarily involved: the Lungs (which regulate the upper distribution of fluids), the Spleen (which transforms and transports fluids in the middle), and the Kidneys (which govern water metabolism from below and control the opening and closing of the water gates). When any of these systems is impaired, fluid accumulates and overflows into the tissues, causing swelling. The Bladder, as the downstream organ of the Kidneys, is responsible for excreting excess fluid as urine. Edema is typically classified as either Yang-type (above the waist, acute, associated with external pathogens) or Yin-type (below the waist, chronic, associated with Spleen or Kidney deficiency).

Why Ze Xie Helps

Ze Xie enters the Kidney and Bladder channels and has a powerful ability to promote urination and drain Dampness. Its bland taste gives it a strong 'seeping' quality that opens the water pathways in the lower body and moves stagnant fluid toward the Bladder for excretion. Its cold nature also helps clear any Heat that may accompany the fluid stagnation. By draining excess water downward and out through the urinary tract, Ze Xie directly addresses the root cause of edema: accumulated fluid that the body cannot properly move or excrete. It works especially well when combined with herbs that strengthen the Spleen (like Bai Zhu) or warm the Yang to assist transformation (like Gui Zhi).

Also commonly used for

Urinary Tract Infection

Especially with Damp-Heat signs like burning or turbid urine

Diarrhea

Watery diarrhea from failure to separate clear and turbid fluids

Fatty Liver

Related to Dampness and turbid Phlegm accumulation in the Liver

Hypertension

Especially when accompanied by Dampness and Phlegm

Meniere's Disease

Inner ear vertigo related to fluid retention

Diabetes

The traditional 'wasting-thirsting' disorder with fluid imbalance

Glomerulonephritis

Kidney inflammation with edema and urinary changes

Herb Properties

Every herb has an inherent temperature, taste, and affinity for specific channels — these properties determine how it interacts with the body

Temperature

Cold

Taste

Sweet (甘 gān), Bland (淡 dàn)

Channels Entered

Kidneys Urinary Bladder

Parts Used

Tuber (块茎 kuài jīng / 块根 kuài gēn)

Dosage & Preparation

These are general dosage guidelines for Ze Xie — always follow your practitioner's recommendation, as dosages vary based on the formula and your individual condition

Standard dosage

6-10g

Maximum dosage

Up to 30g in acute cases of severe edema or phlegm-fluid retention, under practitioner supervision. At doses above 30g, the herb may also promote bowel movements in addition to diuresis.

Dosage notes

Use the standard range of 6-10g for general water-draining and damp-clearing purposes. For phlegm-fluid retention causing dizziness (as in Ze Xie Tang), classical sources use a proportionally larger dose relative to Bai Zhu. For conditions involving damp-heat in the lower body (hot painful urination, turbid discharge), standard doses suffice. When used within tonic formulas like Liu Wei Di Huang Wan, a moderate dose balances the rich, cloying nature of the tonic herbs. Different processing forms suit different purposes: raw Ze Xie has the strongest water-draining action and is best for edema and hot painful urination; bran-fried Ze Xie (麸炒泽泻) is milder and more suited for dizziness and Spleen-related diarrhea; salt-processed Ze Xie (盐泽泻) enhances its action on the Kidney channel for lower back pain and soreness.

Preparation

No special decoction handling is required. Ze Xie is simply decocted with the other herbs in the standard manner.

Processing Methods

In TCM, the same herb can be prepared in different ways to change its effects — here's how processing alters what Ze Xie does

Processing method

Ze Xie slices are sprayed and mixed evenly with salt water, allowed to absorb briefly, then stir-fried over low heat until the surface turns slightly yellow. Ratio: 2kg salt per 100kg Ze Xie slices.

How it changes properties

Salt processing guides the herb's action downward to the Kidneys (salt enters the Kidney channel). It enhances Ze Xie's ability to drain Kidney Deficiency Heat and strengthens its urination-promoting effect while reducing the risk of depleting Yin. The overall cold nature is preserved but refined in its targeting. The taste becomes slightly salty.

When to use this form

Preferred when the treatment target is the Kidneys specifically, such as for lower back heaviness and pain, weak and sore knees, nocturnal emissions, or urinary problems related to Kidney Deficiency Heat. Also preferred when it is important to promote urination without damaging Kidney Yin.

Common Herb Pairs

These ingredients are traditionally combined with Ze Xie for enhanced therapeutic effect

Bai Zhu
Bai Zhu Ze Xie 5 : Bai Zhu 2 (following the original Ze Xie Tang proportions)

Ze Xie drains accumulated water and Dampness downward through the Bladder, while Bai Zhu strengthens the Spleen to transform and transport fluids properly. Together they address both the root (weak Spleen fluid metabolism) and the branch (fluid accumulation) of water retention. This is the classical pairing from Ze Xie Tang in the Jin Gui Yao Lue.

When to use: Dizziness and vertigo from Phlegm-fluid retention beneath the Heart, watery diarrhea from impaired water-grain separation, and general edema with Spleen weakness.

Fu Ling
Fu Ling 1:1 (both commonly used at 9-15g)

Both herbs drain Dampness and promote urination, but through complementary mechanisms. Fu Ling gently seeps Dampness while also strengthening the Spleen and calming the Heart. Ze Xie is more forceful in its water-draining action and also clears Heat from the Bladder. Together they provide thorough drainage of Dampness from multiple levels of the body.

When to use: Edema with scanty urination, water accumulation with palpitations or anxiety, and general fluid metabolism disorders. This pair appears in Wu Ling San and many other classical water-regulating formulas.

Mu Dan Pi
Mu Dan Pi 1:1 (commonly 6-10g each)

Ze Xie drains Kidney Deficiency Fire downward through the urine, while Mu Dan Pi (Moutan bark) cools the Blood and clears Liver-Gallbladder Heat. Together they comprehensively clear the pathological Heat that arises when Kidney Yin is depleted, one working through the water pathway and the other through the Blood level.

When to use: Kidney Yin Deficiency with flaring Deficiency Fire causing night sweats, nocturnal emissions, tidal fever, or dizziness. This classic pairing appears in Liu Wei Di Huang Wan as the two 'draining' herbs.

Zhu Ling
Zhu Ling 1:1 (commonly 9-15g each)

Both are powerful Dampness-draining herbs that promote urination, but Ze Xie also clears Heat while Zhu Ling is neutral and focuses purely on opening the water passages. Their combined diuretic effect is significantly stronger than either herb alone.

When to use: Severe edema, urinary retention, or water accumulation requiring strong diuresis. This pair appears together in Wu Ling San and Zhu Ling Tang.

Key Formulas

These well-known formulas feature Ze Xie in a prominent role

Wu Ling San 五苓散 King

Wu Ling San from the Shang Han Lun is one of the most important water-regulating formulas in all of TCM. Ze Xie serves as the King herb at the highest dose (15g), showcasing its primary action of promoting urination and draining Dampness. The formula treats water accumulation with difficult urination, thirst, and edema, making it the definitive demonstration of Ze Xie's core water-draining function.

Liu Wei Di Huang Wan 六味地黃丸 Assistant

In this famous Kidney Yin-nourishing formula, Ze Xie plays the critical role of draining turbid Dampness and Deficiency Fire from the Kidneys. It is one of the 'three draining' herbs that balance the 'three tonifying' herbs, demonstrating the classical principle that effective tonification requires simultaneous elimination of pathological excess. This formula highlights Ze Xie's ability to drain Kidney Deficiency Fire and its role in Yin Deficiency patterns.

Dang Gui Shao Yao San 當歸芍藥散 Assistant

In this Jin Gui Yao Lue formula for abdominal pain during pregnancy and menstruation, Ze Xie is used at a substantial dose (half a jin in the original) to drain accumulated water and Dampness from the lower body. It partners with Fu Ling and Bai Zhu to resolve fluid stagnation, while Dang Gui, Shao Yao, and Chuan Xiong nourish and regulate Blood. This formula demonstrates Ze Xie's role in gynecological conditions where water and Blood stagnation intertwine.

Comparable Ingredients

These ingredients have overlapping uses — here's how to tell them apart

Fu Ling
Ze Xie vs Fu Ling

Both drain Dampness and promote urination, but Fu Ling is neutral in temperature and also tonifies the Spleen and calms the Spirit. Ze Xie is cold, making it better suited when there is accompanying Heat, and it has a stronger, more direct water-draining action. Fu Ling is gentle enough for long-term use and does not risk depleting Yin, while Ze Xie's cold draining nature can damage Yin with prolonged or excessive use. Choose Fu Ling when there is Spleen weakness with mild Dampness or when the Spirit needs calming; choose Ze Xie when Dampness is severe, Heat is present, or rapid water drainage is needed.

Zhu Ling
Ze Xie vs Zhu Ling

Both are strong water-draining herbs, but Zhu Ling is neutral in temperature and focuses purely on promoting urination, while Ze Xie is cold and additionally clears Heat and drains Kidney Deficiency Fire. Zhu Ling lacks Ze Xie's Heat-clearing action but also carries less risk of cold damage to the Spleen. For Damp-Heat patterns, Ze Xie is generally preferred; for pure water accumulation without Heat, Zhu Ling may be more appropriate.

Che Qian Zi
Ze Xie vs Che Qian Zi

Both promote urination and clear Heat, but Che Qian Zi (plantain seed) also clears the Liver and benefits the eyes, expels Phlegm, and is specifically indicated for Lung Heat with cough. Ze Xie has a stronger overall water-draining action and uniquely drains Kidney Deficiency Fire, making it more appropriate for Kidney-related fluid disorders and Yin Deficiency patterns. Che Qian Zi is often chosen when eye problems, Liver Heat, or Phlegm-related cough accompany the Dampness.

Common Substitutes & Adulterants

Related species and common adulterations to be aware of when sourcing Ze Xie

Ze Xie has three main commercial grades based on origin: Jian Ze Xie (建泽泻, from Fujian, considered the highest quality), Chuan Ze Xie (川泽泻, from Sichuan), and Guang Ze Xie (广泽泻, from Guangdong/Guangxi, generally lower quality with shorter growing time and less starchy tubers). Chuan Ze Xie has less prominent ring-like surface grooves, a more pointed lower end, and a more yellow-brown surface. Guang Ze Xie tends to be elongated, lighter in weight, less starchy, and more variable in taste. Additionally, the European water plantain (Alisma plantago-aquatica L.) is a closely related species sometimes encountered, but it is considered a different medicinal substance. Immature or prematurely harvested tubers from any region will be smaller, less starchy, and more bitter, indicating lower quality.

Educational content — always consult a qualified healthcare provider or TCM practitioner before using any herb.

Toxicity Classification

Classical Chinese pharmacopoeia toxicity rating for Ze Xie

Non-toxic

Ze Xie is classified as non-toxic in classical sources (the Shen Nong Ben Cao Jing explicitly states "无毒"). However, modern pharmacological research has identified that high-dose or prolonged use can lead to water-electrolyte imbalance and, in animal models at very high doses, potential hepatotoxicity and nephrotoxicity. The primary active compounds are protostane-type triterpenoids (alisols A, B, and their acetate derivatives), which are unique to the Alisma genus. Fresh roots and leaves of the related European species (A. plantago-aquatica) are considered irritant and mildly toxic when raw, but drying and processing deactivates these compounds. Standard decoction preparation at normal doses (6-10g) is considered safe. Classical texts warn that prolonged use causes blurred vision (目昏) due to excessive drainage of body fluids depleting Kidney Qi.

Contraindications

Situations where Ze Xie should not be used or requires extra caution

Caution

Kidney deficiency with spermatorrhea (seminal emission from Qi weakness, not from Heat). Ze Xie's cold, draining nature further depletes Kidney Qi and worsens the slipping of essence. As the Ben Cao Tong Xuan states, when Qi sinks and essence is already slippery, Ze Xie's descending action makes it worse.

Caution

Yin deficiency without dampness or fluid retention. Ze Xie is a strong water-draining herb that can further deplete body fluids and Yin. Zhang Jingyue's principle applies: 'draining water does not nourish Yin.'

Caution

Yang deficiency with chronic cold-type diarrhea. Ze Xie is cold in nature and promotes urination, which further weakens Spleen Yang and worsens diarrhea from deficiency cold.

Caution

Prolonged use at high doses without clinical indication. Long-term or excessive use may lead to electrolyte imbalance, and animal studies suggest potential hepatotoxicity and nephrotoxicity at very high doses.

Caution

Blurred vision from Kidney Yin depletion. Classical texts warn that prolonged use causes 'eye dimness' (目昏) because excessive urination depletes Kidney Qi, which governs the eyes.

Special Populations

Important considerations for pregnancy, breastfeeding, and pediatric use

Pregnancy

Ze Xie should be used with caution during pregnancy. While classical texts record its use in pregnancy-related edema (the formula Ze Xie San from Fu Ren Liang Fang treats generalized edema in pregnancy), its strong water-draining and cold properties mean it should only be used under practitioner supervision when a clear pattern of dampness or fluid retention is present. There is no specific evidence of teratogenicity, but its potent diuretic effect could theoretically reduce amniotic fluid or cause electrolyte disturbance if used excessively. It is not classified among the traditionally prohibited pregnancy herbs, but caution is warranted.

Breastfeeding

There is limited specific data on Ze Xie during breastfeeding. Its strong diuretic action could theoretically reduce milk production by depleting body fluids. Interestingly, the Shen Nong Ben Cao Jing records it as treating 'difficult lactation' (乳难), and some classical commentators interpreted this as promoting milk flow through its ability to open waterways. However, this traditional claim was later disputed. In practice, nursing mothers should avoid Ze Xie unless prescribed by a practitioner for a specific dampness-related condition, and only at low doses for short durations.

Children

Ze Xie may be used in pediatric prescriptions at reduced doses appropriate to the child's age and weight, typically one-third to one-half of the adult dose. It is most commonly encountered in pediatric formulas for phlegm-fluid conditions causing cough or for urinary difficulty. Due to its cold nature and diuretic effect, it should be used cautiously and for short durations in children, as their Spleen and Kidney systems are still developing and more vulnerable to cold, draining herbs.

Drug Interactions

If you are taking pharmaceutical medications, be aware of these potential interactions with Ze Xie

Diuretic medications: Ze Xie has demonstrated diuretic activity in pharmacological studies. Concurrent use with pharmaceutical diuretics (thiazides, loop diuretics, potassium-sparing diuretics) could potentially enhance fluid loss and increase the risk of electrolyte imbalance, particularly hypokalemia or dehydration.

Antidiabetic medications: Ze Xie has been shown to have hypoglycemic effects in preclinical studies. Patients taking insulin or oral hypoglycemic agents should be monitored for additive blood sugar lowering effects.

Lipid-lowering drugs (statins): Ze Xie has demonstrated hypolipidemic effects and may have additive effects with statins or other lipid-lowering medications. While this could be beneficial, liver function should be monitored, as both Ze Xie (at high doses) and statins carry hepatotoxicity risks.

Cytochrome P450 interactions: A preclinical study found that Ze Xie extract can influence rat CYP450 enzymes (CYP1A2, CYP2C9, CYP2E1, CYP3A4) at high doses. While human clinical data is lacking, caution is advised with drugs that are extensively metabolized by these pathways.

Dietary Advice

Foods and dietary considerations when taking Ze Xie

When taking Ze Xie for dampness or fluid retention, avoid greasy, rich, and overly sweet foods that generate dampness and impede the herb's draining action. Cold and raw foods should also be limited, as they can injure the Spleen's ability to transform fluids, working against the treatment goal. Lightly cooked, warm foods that support Spleen function (such as congee, cooked grains, and mild soups) are preferred. Adequate but not excessive water intake is appropriate, as the herb promotes urination.

Botanical Description

Physical characteristics and morphology of the Ze Xie source plant

Alisma orientale (Sam.) Juzep. is an aquatic or semi-aquatic perennial herb in the family Alismataceae, commonly known as Asian water plantain. It grows 30 to 90 cm tall and thrives in shallow water, marshlands, rice paddies, pond edges, and boggy lowlands. The plant produces a rosette of broad, ovate to elliptical basal leaves with long petioles, and the leaf shape may vary depending on whether the foliage is submerged or emergent.

In summer, a single erect flowering stalk rises well above the leaf rosette, bearing whorled panicles of small, three-petalled flowers that are white to pale pink. The underground portion consists of a starchy, rounded to egg-shaped tuber (块茎), which is the medicinal part. This tuber is typically 2 to 7 cm long and 2 to 6 cm in diameter, with a firm, dense texture and a yellowish-white, powdery cross-section containing numerous tiny pores.

Sourcing & Harvesting

Where Ze Xie is sourced, when it's harvested or collected, and how to assess quality

Harvesting season

Winter (late December to February), when the above-ground stems and leaves begin to wither and the tuber has fully matured.

Primary growing regions

The highest quality Ze Xie has traditionally been "Jian Ze Xie" (建泽泻), produced in the Jian'ou and Jianning areas of Fujian province, considered the premier dao di (道地) source since the Ming-Qing period. Sichuan province (川泽泻) is the other major production area. Jiangxi province (particularly Guangchang county) also produces significant quantities of the Jian-type Ze Xie, introduced from Fujian during the Qing dynasty. Smaller quantities are cultivated in Guangdong, Guangxi, Hubei, and Hunan. The plant is widely distributed across northeast and southwest China in wild form, but commercial herb material is predominantly from cultivated crops in Fujian and Sichuan.

Quality indicators

Good quality Ze Xie tubers are large, firm, and heavy with a solid texture. The surface should be pale yellow to yellowish-white, smooth, and display characteristic irregular horizontal ring-like grooves and small bumpy root scars. The cross-section should be yellowish-white, starchy (powdery), and show numerous tiny pores. The smell is faint and the taste slightly bitter. Jian Ze Xie (from Fujian) is traditionally considered superior, recognized by its rounded, compact shape, prominent ring-like ridges on the surface, and especially dense starchy flesh. Avoid pieces that are light, spongy, hollow, dark-colored, or insect-damaged. For sliced material, look for large, uniformly thick slices with a dense powdery texture.

Classical Texts

Key passages from the classical Chinese medical texts that describe Ze Xie and its therapeutic uses

Shen Nong Ben Cao Jing (《神农本草经》)

Original: 味甘，寒，无毒。治风寒湿痹，乳难，消水，养五脏，益气力，肥健。久服耳目聪明，不饥，延年，轻身，面生光，能行水上。

Translation: Sweet in flavour, cold in nature, non-toxic. Treats painful obstruction from wind, cold, and dampness; difficult lactation; and eliminates water. Nourishes the five organs, strengthens Qi and physical vigour. Prolonged use sharpens hearing and sight, prevents hunger, extends life, lightens the body, brightens the complexion, and enables one to walk on water.

Ben Cao Gang Mu (《本草纲目》) by Li Shizhen

Original: 泽泻，气平，味甘而淡，淡能渗泄，气味俱薄，所以利水而泄下。脾胃有湿热，则头重而目昏耳，泽泻渗去其湿，则热亦随去，而土气得令，清气上行，天气明爽，故泽泻有养五脏、益气力、治头旋、聪明耳目之功。若久服则降令太过，清气不升，真阴潜耗，安得不目昏耶？

Translation: Ze Xie is neutral in Qi, sweet and bland in flavour. Blandness promotes seepage and drainage; both its Qi and flavour are thin, hence it drains water downward. When the Spleen and Stomach harbour damp-heat, the head feels heavy and the eyes become dim. Ze Xie seeps out the dampness, and the heat departs with it; Earth Qi regains its function, clear Qi rises, and clarity returns. Thus Ze Xie can nourish the organs, strengthen vitality, treat dizziness, and sharpen the senses. However, if taken too long, its descending action becomes excessive, clear Qi fails to rise, and true Yin is silently consumed. How could the eyes not become dim?

Ben Cao Zheng Yi (《本草正义》) by Zhang Shanlei

Original: 泽泻，最善渗泄水道，专能通行小便。

Translation: Ze Xie excels above all at seeping and draining the waterways, and its specialty is promoting urination.

Jin Gui Yao Lue (《金匮要略》) by Zhang Zhongjing

Original: 心下有支饮，其人苦冒眩，泽泻汤主之。

Translation: When there is a branching fluid retention below the heart, and the person suffers from dizziness and a foggy sensation in the head, Ze Xie Tang (Ze Xie Decoction) governs this.

Historical Context

The history and evolution of Ze Xie's use in Chinese medicine over the centuries

Ze Xie (泽泻) literally translates as "marsh drain," a name that perfectly captures both its aquatic habitat and its primary therapeutic action of draining dampness and water. It was first recorded in the Shen Nong Ben Cao Jing (circa 1st-2nd century CE) as a top-grade herb with remarkably extravagant claims, including prolonging life, lightening the body, and enabling one to "walk on water." These poetic descriptions likely reflect its Daoist associations with water mastery and spiritual refinement.

The herb's reputation underwent a fascinating evolution across Chinese medical history. Before the Song dynasty, Ze Xie was credited with three main functions: tonifying, draining water, and clearing heat. From the Song dynasty onward, physicians began questioning its tonic properties. Li Dongyuan (Jin dynasty) clarified its role as clearing residual dampness from the Bladder. Li Shizhen (Ming dynasty) argued decisively that its tonic reputation was indirect: by clearing damp-heat, Spleen function recovers and the body naturally strengthens. By the Qing dynasty, the Ben Cao Zheng Yi declared its tonic claims "excessive praise with no practical clinical significance," and its core function was firmly established as water drainage alone. This evolution from mystical panacea to clinically precise diuretic herb is a microcosm of how TCM matured over two millennia.

Ze Xie remains a critical ingredient in many iconic formulas, including Wu Ling San (Five-Ingredient Powder with Poria) from the Shang Han Lun, Ze Xie Tang from the Jin Gui Yao Lue, and Liu Wei Di Huang Wan (Six-Ingredient Pill with Rehmannia). In the last formula, its role sparked centuries of debate: does it merely guide other herbs to the Kidney channel, or does it serve a more essential function of draining pathological water from the Kidney to allow tonification to work? Li Shizhen settled the debate by arguing that it drains Bladder pathogenic Qi, enabling the tonic herbs to take effect.

Modern Research

4 published studies investigating the pharmacological effects or clinical outcomes of Ze Xie

1

Comprehensive review on ethnomedicinal application, phytochemistry, pharmacology, and toxicology of Rhizoma Alismatis (2015)

Tian T, Chen H, Hao YY. Traditional uses, phytochemistry, pharmacology, toxicology and quality control of Alisma orientale (Sam.) Juzep: A review. Journal of Ethnopharmacology, 2014, 158 Pt A: 373-387.

This review covered the traditional uses, chemical composition, and pharmacological activities of Ze Xie. It confirmed that its main bioactive compounds are protostane-type triterpenoids (alisols), with demonstrated diuretic, lipid-lowering, hepatoprotective, anti-inflammatory, immunomodulatory, and antitumor activities. The review also noted that high-dose or long-term use may cause electrolyte imbalance, bloody urine, or potential liver and kidney toxicity.

PubMed
2

Literature review on pharmacological activities against nonalcoholic fatty liver disease and metabolic syndrome (2019)

Loh KW, Tam YC, Lee IK, et al. Pharmacological Activities of Alisma orientale against Nonalcoholic Fatty Liver Disease and Metabolic Syndrome: Literature Review. Evidence-Based Complementary and Alternative Medicine, 2019, Article ID 2576898.

This review of preclinical studies found that Alisma orientale extracts and key compounds (especially alisol A 24-acetate and alisol B 23-acetate) prevented hepatic triglyceride accumulation by suppressing de novo lipogenesis and increasing lipid export. The herb also controlled oxidative stress, lipoapoptosis, inflammation, and fibrosis markers relevant to fatty liver disease and metabolic syndrome.

PubMed
3

Diuretic activity of compatible triterpene components of Alismatis rhizoma (Preclinical, 2017)

Zhang X, Li XY, Lin N, et al. Diuretic Activity of Compatible Triterpene Components of Alismatis Rhizoma. Molecules, 2017, 22(9): 1459.

This study investigated the diuretic mechanisms of Ze Xie's triterpene components in animal models. The compatible triterpene fractions demonstrated significant diuretic activity, supporting the herb's traditional use for promoting urination and resolving water retention.

4

Protective effects against ER stress-induced hepatic steatosis (Preclinical, 2015)

Kim KA, Lee IA, Gu W, et al. Protective Effects of Alisma orientale Extract against Hepatic Steatosis via Inhibition of Endoplasmic Reticulum Stress. International Journal of Molecular Sciences, 2015, 16(11): 26151-26166.

This in vitro and in vivo study showed that methanol extract of Alisma orientale tuber inhibited endoplasmic reticulum stress markers (GRP78, CHOP, XBP-1) in liver cells and reduced triglyceride accumulation in both cell models and high-fat diet mice, supporting its traditional use for resolving dampness and its modern application in fatty liver conditions.

PubMed

Research on individual TCM herbs is growing but still limited by Western clinical trial standards. These studies provide emerging evidence and should be considered alongside practitioner expertise.