Hu Zhang (虎杖) — Giant Knotweed | TCM Herb Guide

At a Glance

• Herb: Hu Zhang
• Chinese name: 虎杖 (Hǔ Zhàng)
• Latin name: Polygoni cuspidati Rhizoma et Radix
• Nature: Slightly Cold
• Taste: Bitter
• Meridian: Liver / Gallbladder / Lung
• Category: Herbs that Invigorate Blood and Transform Stasis
• Introduction: Hu Zhang (虎杖), Radix Polygoni Cuspidati, is the dried root and rhizome of Reynoutria japonica (syn. Polygonum cuspidatum). A versatile multi-action herb, it clears heat, resolves toxicity, activates blood stasis, promotes urination, relieves jaundice, and transforms phlegm. Notably rich in resveratrol and emodin, Hu Zhang has attracted extensive modern research interest for cardiovascular protection, anti-inflammatory, antiviral, and antitumor properties.

Action

• Clears heat and resolves toxicity
• Activates blood and resolves stasis
• Promotes urination and relieves jaundice
• Stops cough and transforms phlegm
• Relieves pain from blood stasis

Clinical Application

• Damp-heat jaundice — combines with Yin Chen, Zhi Zi, Da Huang
• Blood stasis pain: traumatic injury, amenorrhea, dysmenorrhea — combines with Dang Gui, Hong Hua, Yan Hu Suo
• Burns and scalds (topical): crushed root or powder applied to burns
• Lung heat cough with phlegm — combines with Huang Qin, Gua Lou, Zhe Bei Mu
• Urinary stones with damp-heat — combines with Jin Qian Cao, Shi Wei
• Snake bites and toxic sores — topical and internal use

Precautions

• Dosage: 9–15 g in decoction
• Contraindicated in pregnancy — activates blood and promotes downward movement
• Use with caution in spleen deficiency with loose stools (contains emodin anthraquinones)
• Large doses may cause diarrhea — reduce dose or combine with stomach-protecting herbs
• Topical use for burns is generally safe and effective

Formula

• Hu Zhang San (虎杖散): Hu Zhang alone as powder for burns — traditional topical formula
• Hu Zhang + Yin Chen + Da Huang decoction — clears damp-heat jaundice, modern hepatitis formula
• Hu Zhang Wan (虎杖丸): Hu Zhang, Dang Gui, Chuan Xiong, Hong Hua — activates blood, relieves trauma pain
• Modern: resveratrol extract standardized from Hu Zhang root — cardiovascular supplement

Combinations

• Giant Knotweed Rhizome (虎杖) + Virgate Wormwood Herb (茵陈) + Lysimachia Herb (金钱草) → clear liver-gallbladder damp-heat; jaundice, gallstones, and hepatitis
• Giant Knotweed Rhizome (虎杖) + Salvia Root (丹参) + Curcuma Root (郁金) → activate blood, resolve stasis; liver fibrosis and blood stasis with heat
• Giant Knotweed Rhizome (虎杖) + Mulberry Root Bark (桑白皮) + Scutellaria Root (黄芩) → clear lung heat, resolve phlegm; cough with yellow sputum and lung abscess
• Giant Knotweed Rhizome (虎杖) + Rhubarb Root (大黄) + Mirabilite (芒硝) → clear heat, purge stasis; constipation from heat accumulation
• Giant Knotweed Rhizome (虎杖) + Dandelion (蒲公英) + Patrinia Herb (败酱草) → clear heat toxin; pelvic inflammatory disease and toxic infections

Pharmacological Effects

• Resveratrol: antioxidant, cardioprotective, antitumor, anti-aging; anti-inflammatory
  • COX-2 inhibition
• Antibacterial and antiviral
  • hepatitis B, influenza
• Hepatoprotective; choleretic; laxative
  • emodin
• Lowers blood lipids and glucose; estrogenic
  • mild

Classic Description

• Ming Yi Bie Lu (《名医别录》): ‘Governs opening and regulating menstruation, and breaking blood stasis masses.’
• Ben Cao Gang Mu (《本草纲目》): ‘Giant Knotweed Rhizome: bitter nature descends and promotes urination; slightly cold nature clears heat; disperses blood and breaks stasis; benefits the gallbladder and reduces jaundice; stops cough and transforms phlegm.’
• Yao Xing Lun (《药性论》): ‘Treats great heat with vexation and agitation, stops thirst, promotes urination, and suppresses all heat toxins.’
• Ben Cao Bei Yao (《本草备要》): ‘Drains heat, moves blood, unblocks the channels, drains dampness; treats jaundice, turbid urine, fractures, blood stasis, and carbuncle toxin.’