Roots and rhizomesDampness-drainingPolygoni Cuspidati Rhizoma et Radix

Hu Zhang (Giant Knotweed Root)

虎杖 · Hu Zhang

Dampness-draining herb in Traditional Chinese Medicine. Traditional functions: Drains dampness and reduces jaundice, clears heat and resolves toxin, dispels stasis and stops pain, resolves phlegm and stops cough.

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Quick Facts

Latin Name	Polygoni Cuspidati Rhizoma et Radix
Chinese Name & Pinyin	虎杖 · Hu Zhang
Medicinal Part	Roots and rhizomes
Efficacy Category	Dampness-draining
Botanical Origin	The dried root and rhizome of Polygonum cuspidatum Sieb. et Zucc.(Polygonaceae)
Nature & Flavour	Bitter; Slightly cold
Channels Entered	Liver, Gallbladder, Lung

What Is Hu Zhang?

Hu Zhang (Giant Knotweed Root) is a medicinal herb of Traditional Chinese Medicine.

Primarily produced in the Chinese provinces of Jiangsu, Zhejiang, Guangdong, Anhui.

Nature & Flavour: Bitter; Slightly cold
Channels Entered: Liver, Gallbladder, Lung

Hu Zhang: Materia Medica Profile

Identification & Quality Standard

Polygoni Cuspidati Rhizoma et Radix

Botanical Origin

The dried root and rhizome of Polygonum cuspidatum Sieb. et Zucc.(Polygonaceae)

Production Regions

Primarily produced in the Chinese provinces of Jiangsu, Zhejiang, Guangdong, Anhui.

Quality Requirements

Superior medicinal material is thick and strong, with firm and yellow fractured surface.

Macroscopic Features

Often cylindrical short sections or irregular thick pieces, 1~7cm long, 0.5~2.5cm diameter. Outer skin is brown, with longitudinal wrinkles and rootlet scars, cut surface has relatively thin cortex, and wide xylem, brown, radial rays, cortex and xylem are easily separated. Pith of rhizome has a septum or hollow-shape. Hard texture, faint odor, slightly bitter and astringent taste.

Traditional TCM Properties

Bitter; Slightly coldLiverGallbladderLung

Traditional Functions

Drains dampness and reduces jaundice, clears heat and resolves toxin, dispels stasis and stops pain, resolves phlegm and stops cough.

How Hu Zhang Is Used in TCM

In the Chinese materia medica, Hu Zhang is classified among the Dampness-draining herbs.

Classical Formulas Containing Hu Zhang

Formula One: Hu Zhang San

How it is built: In this formula, Hu Zhang is the main herb (sovereign), leading the stagnant-blood pain-easing role. It is typically paired with blood-moving herbs such as Dang Gui and Hong Hua to open blood stasis, and may include Niu Xi to guide the action downward and ease lower-limb joint pain. Using Hu Zhang alone is not enough — a single herb cannot cover the blood-moving, qi-moving, and pain-easing needs together.

Traditional use: This formula was used for bruising and joint pain from blood stasis — local swelling and pain, bruises, and a fixed, unchanging pain.

Modern note: Any modern use should go through proper assessment — do not self-apply based on the name.

Formula Two: Yin Chen Hu Zhang Tang

How it is built: In this formula, Yin Chen is the main herb and Hu Zhang is a supporting herb (minister), working together to clear liver-gallbladder damp-heat. Zhi Zi and Da Huang help the body expel damp-heat. Hu Zhang's job here is to assist the clearing while also helping move stasis, working with Yin Chen to ease yellowing.

Traditional use: This formula was used for damp-heat jaundice — yellowing of the skin and eyes, dark urine, a bitter dry mouth, and a greasy yellow tongue coating.

Modern note: As with any formula, use should follow proper assessment — a practitioner adjusts the pairing and dose to the type of jaundice. Do not self-administer.

Formulas vs. Single Herbs

A formula combines several herbs to create a whole effect. This is different from using a single herb in one key way:

Formulas are built for balance — different herbs cover different patterns and restrain each herb's bias.
A single herb cannot copy a full formula — the dose and pairing are designed as a whole, enabling synergy or restraint.
Do not build your own formulas from online articles, and do not take a single herb to replace a formula — the effect comes from the combination.

Hu_Zhang

Frequently Asked Questions

What is Huzhang? Is it the same as Yinchen or Dahuang?

Huzhang is the dried rhizome and root of Reynoutria japonica, Latin name Polygoni Cuspidati Rhizoma et Radix. It is a common Chinese medicine centered on draining dampness and clearing jaundice, clearing heat and detoxifying, dispersing stasis and relieving pain, and stopping cough and transforming phlegm. Yinchen drains dampness and clears jaundice. Dahuang purges downward and attacks accumulation. They cannot be used interchangeably in equal amounts. Prescribe as Huzhang. Caution in pregnancy.

What are the composition and effects of Huzhang?

Pharmacopoeial name Huzhang, Latin Reynoutria japonica Houtt. Slightly bitter in taste, slightly cold in nature, enters the Liver, Gallbladder and Lung meridians. Functions to drain dampness and clear jaundice, clear heat and detoxify, disperse stasis and relieve pain, and stop cough and transform phlegm. Used for damp-heat jaundice, turbid strangury, leukorrhea, wind-damp bi pain, abscesses and sores, burns and scalds, amenorrhea, abdominal masses, traumatic injuries, and lung heat cough. Drains dampness and disperses stasis.

How to choose between raw and processed? Can Yinchen replace it?

Rhizome is used raw. Yinchen emphasizes jaundice rather than strongly dispersing stasis, and cannot replace it in equal amounts. Commercial products are standardized; do not adjust arbitrarily.

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Learn More About Hu Zhang

Explore our in-depth article covering the traditional uses, properties, functions, and TCM context of Hu Zhang.

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Medical Disclaimer — This article is provided for educational purposes only and describes traditional Chinese medicine concepts. It is not medical advice, and it is not intended to diagnose, treat, cure or prevent any disease. Always consult a qualified practitioner before using any herb, particularly if you are pregnant, nursing, taking medication or managing a diagnosed condition.