Ze Xie (泽泻) — Alisma Herb in TCM | Diuretic, Dizziness & Lipid-Lowering

At a Glance

• Herb: Ze Xie
• Chinese name: 泽泻 (Zé Xiè)
• Latin name: Rhizoma Alismatis
• Nature: Cold
• Taste: Sweet / Bland
• Meridian: Kidney / Urinary Bladder
• Category: Herbs that Drain Dampness
• Introduction: Ze Xie (泽泻, Rhizoma Alismatis) is the dried tuber of Alisma plantago-aquatica L. var. orientale (Samuel.) Juzep., an aquatic plant found in marshes, lakes, and rice paddies throughout China and East Asia. The name 泽泻 — ‘marsh-drainer’ — reflects both its habitat and its primary clinical action: guiding water and dampness downward through the Kidney and Urinary Bladder. One of the oldest TCM diuretics, Ze Xie appears in the Shennong Bencao Jing as an upper-grade herb with remarkable longevity-promoting claims. In modern TCM practice it is valued for its potent diuretic, lipid-lowering, and anti-dizziness effects, and it remains a key constituent of Liu Wei Di Huang Wan and Wu Ling San.

Action

• Promotes urination and drains dampness: The primary action — strongly promotes diuresis to eliminate water-dampness accumulation in the Lower Jiao. 2. Drains Kidney fire (xiang huo): Reduces ministerial fire rising from the Kidney; prevents the tonic herbs in Liu Wei Di Huang Wan from causing heat accumulation. 3. Clears damp-heat from the Lower Jiao: Used for turbid painful urination, urinary tract infections, and damp-heat leucorrhoea. 4. Calms dizziness from phlegm-turbidity: Addresses vertigo and dizziness caused by water turbidity rising to disturb the head.

Clinical Application

• Ze Xie is essential for conditions involving water retention, dampness, and damp-heat in the Lower Jiao: dysuria, edema, diarrhea, and urinary tract infections. Its pairing with Fu Ling in Wu Ling San creates the classical formula for water retention with thirst and difficult urination after febrile disease. In Liu Wei Di Huang Wan, Ze Xie’s draining action balances the enriching qualities of Shu Di Huang and Shan Zhu Yu — preventing stagnation and heat accumulation. For dizziness from phlegm-water, Ze Xie is combined with Bai Zhu in Ze Xie Tang (泽泻汤) — one of the simplest and most elegant two-herb formulas in the Jin Gui Yao Lue. Modern applications include hyperlipidemia, non-alcoholic fatty liver disease, Meniere’s disease, and hypertension.

Precautions

• Use with caution in patients with Kidney yin deficiency without damp-heat — prolonged use may further damage yin. Contraindicated in patients with renal failure or severe dehydration. Long-term use requires monitoring of renal function and electrolytes. Some animal studies suggest potential nephrotoxicity at high doses — stay within clinical dosage range (6–12 g). Use cautiously with potassium-sparing diuretics (pharmacodynamic interaction).

Formula

• Wu Ling San (五苓散): Ze Xie, Fu Ling, Zhu Ling, Bai Zhu, Gui Zhi — water retention with thirst.
• Ze Xie Tang (泽泻汤): Ze Xie, Bai Zhu — dizziness from phlegm-water.
• Liu Wei Di Huang Wan (六味地黄丸): Shu Di Huang, Shan Zhu Yu, Shan Yao, Ze Xie, Fu Ling, Mu Dan Pi — Kidney-Liver yin deficiency.

Combinations

• Ze Xie + Fu Ling + Zhu Ling + Bai Zhu + Gui Zhi (Wu Ling San): Water retention with thirst and difficult urination. Source: Shang Han Lun (伤寒论).
• Ze Xie + Bai Zhu (Ze Xie Tang): Dizziness from phlegm-water turbidity. Source: Jin Gui Yao Lue (金匮要略).
• Ze Xie + Shu Di Huang + Shan Zhu Yu + Fu Ling (Liu Wei Di Huang Wan): Kidney-Liver yin deficiency with damp-heat; Ze Xie drains to balance. Source: Craft of Medicines and Patterns for Children (小儿药证直诀).
• Ze Xie + Che Qian Zi + Mu Tong: Damp-heat dysuria and urinary tract infections. Source: Formulas to Aid the Living (济生方).
• Ze Xie + Dan Shen + He Shou Wu: Modern combination for hyperlipidemia and non-alcoholic fatty liver disease.

Pharmacological Effects

• Alisol compounds
  • Diuretic: promote renal tubular secretion of sodium and chloride, increasing urine output
  • Diuretic: well-established in animal and human studies
• Alisol B-23 acetate significantly
  • Lipid-lowering: reduces serum triglycerides, LDL-cholesterol, and hepatic lipid deposition in animal models of hyperlipidemia and NAFLD
• Anti-vertigo
  • Reduces endolymph production and labyrinthine fluid pressure — explains classical use in dizziness from water turbidity (Meniere’s disease model)
• Hepatoprotective
  • Reduces hepatic fat accumulation and liver enzyme elevation in fatty liver models
• Antihypertensive
  • Mild blood pressure-lowering effects consistent with diuretic action

Classic Description

• 《神农本草经》(Shennong Bencao Jing, circa 200 CE): ‘泽泻，味甘，寒。主风寒湿痹，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。’ (Ze Xie: sweet flavour, cold. Governs wind-cold-damp Bi, difficult lactation, disperses water, nourishes the five organs, benefits qi and strength. Extended use: sharp hearing and vision, no hunger, prolonged life, light body, luminous complexion, ability to walk on water.)
• 《金匮要略》(Jin Gui Yao Lue, circa 200 CE): ‘心下有支饮，其人苦冒眩，泽泻汤主之。泽泻五两，白术二两，上二味，以水二升，煮取一升，分温再服。’ (When there is suspended fluid below the heart causing dizziness: Ze Xie Tang governs it. Ze Xie 5 liang, Bai Zhu 2 liang; decoct in 2 sheng water to obtain 1 sheng; take in two warm divided doses.)
• 《本草纲目》(Bencao Gangmu, 1596): ‘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，则头重而目昏耳鸣，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。’ (Ze Xie: its qi is balanced, flavour sweet and bland. Blandness percolates and drains; with thin qi and flavour it drains water downward. When Spleen-Stomach harbours damp-heat, the head is heavy, vision blurred, ears ring. Ze Xie percolates the dampness away, and heat leaves with it; earth qi is restored, clear qi rises, the heavenly qi becomes bright — thus Ze Xie has the merit of nourishing the five organs, benefiting strength, treating dizziness, and sharpening hearing and vision.)