☯️Traditional Chinese Medicine

Knotweed (Bian Xu)

Polygonum aviculare

About Knotweed (Bian Xu)

Knotweed (Bian Xu) (Polygonum aviculare) is a herb used in the Traditional Chinese Medicine tradition to help with UTI, Edema, Parasites, and Skin Health. The aerial parts and leaves are the parts traditionally used, used both internally and topically.

Botanical background

Polygonum aviculare or common knotgrass is a plant related to buckwheat and dock. It is also called prostrate knotweed, birdweed, pigweed and lowgrass. It is an annual found in fields and wasteland, with white flowers from June to October. It is widespread across many countries in temperate regions, apparently native to Eurasia and North America, naturalized in temperate parts of the Southern Hemisphere.

Source: Wikipedia, via iNaturalist

Parts used

Aerial Parts · bothLeaves · both

Conditions addressed

🍵

Tea / Infusion

1–3 cups daily
  • Steep 1–2 tsp of dried Knotweed (Bian Xu) in freshly boiled water for 5–10 minutes.
  • Cover while steeping.
  • Strain and drink.
💧

Tincture

20–40 drops in water, 2–3× daily
  • Pack dried Knotweed (Bian Xu) into a jar and cover with 40–60% alcohol.
  • Seal and steep for 4–6 weeks, shaking daily.
  • Strain and store in a dark dropper bottle.
💊

Powder / Capsule

500 mg – 1 g, 1–3× daily
  • Grind dried Knotweed (Bian Xu) into a fine powder.
  • Fill size 00 capsules or stir into smoothies or honey.
🖐️

Topical / Poultice

1–2× daily as needed
  • Mash fresh Knotweed (Bian Xu) or mix the powder with a little water to form a paste.
  • Apply to the affected area for 20–30 minutes.
🫙

Infused Oil

Massage into affected area 1–2× daily
  • Fill a jar with dried Knotweed (Bian Xu).
  • Pour over a carrier oil until submerged.
  • Leave for 4–6 weeks, then strain.
  • Use topically or as a salve base.
🛁

Herbal Bath

2–3× per week as needed
  • Brew 4–6 tbsp of Knotweed (Bian Xu) in 1 litre of hot water for 15 minutes, strain, and add to a warm bath.
  • Soak for 20–30 minutes.

Pregnancy, Breastfeeding & Children

No herb-specific pregnancy/child safety research is documented for Knotweed (Bian Xu) in our references — the guidance below is based on its general effect category, not research on Knotweed (Bian Xu) itself. Always confirm with a midwife, doctor, or pediatrician.

Pregnancy

Use Caution

This herb has a diuretic (fluid-eliminating) effect. Pregnancy already involves significant fluid/electrolyte shifts, so diuretic herbs are generally used cautiously and in moderation rather than as a routine remedy — this is a general, mechanism-based caution, not herb-specific research.

Breastfeeding

Use Caution

Diuretic herbs are traditionally thought to potentially reduce milk supply through fluid loss — generally used cautiously while establishing or maintaining supply.

Children

Use Caution

Children are more sensitive to fluid and electrolyte shifts — diuretic herbs are generally used cautiously and under guidance.

Contraindications

  • Significant kidney impairment — diuretic herbs may worsen renal function

Warnings

⚠️ Kidney Disease

Some diuretic herbs are contraindicated in those with kidney disease. Consult your doctor if you have impaired kidney function.

⚠️ Allergic Reactions

Discontinue immediately if you experience rash, itching, swelling, or difficulty breathing.

⚠️ Not Medical Advice

This information is for educational purposes only. Always consult a qualified healthcare provider before using herbal remedies.

Drug & herb interactions

May have a diuretic effect

Watch for: Diuretic medications and lithium

Additive fluid loss can affect electrolyte balance and change how the body clears lithium.

Where to find in nature

Native region

China, Taiwan, Korea, Japan

Climate

Temperate to subtropical

Habitat

Mountain forests, river valleys, and cultivated herb farms throughout East Asia

🌿 To see Knotweed (Bian Xu) growing, visit botanical gardens, university plant collections, or specialist herb nurseries near you. If foraging in the wild, always work with an expert identifier — never consume a plant you are not 100% certain of.

Where to buy

In store

  • Chinese herbal medicine shops and TCM clinics
  • Chinatown herbal stores and Asian supermarkets with herbal sections
  • Health food stores (Whole Foods, Natural Grocers, Holland & Barrett, GNC)
  • Naturopathic clinics and integrative medicine practices
  • Specialist herbal apothecaries and herbalist practices

Online

iHerb

Wide selection of standardised extracts, capsules, and powders with lab testing

Mountain Rose Herbs

Premium bulk dried herbs — certified organic, ethically sourced

Starwest Botanicals

Large selection of certified organic bulk herbs and powders

Herb Pharm

High-quality liquid extracts and tinctures, rigorous quality standards

Amazon

Convenient — verify brand certifications and check third-party testing

Etsy

Small-batch artisan herbalists, hand-harvested and wildcrafted herbs

Quality tips

When buying Knotweed (Bian Xu), look for: certified organic labelling, clearly stated country of origin, third-party lab testing for heavy metals and pesticides, and a batch expiry date. Standardised extracts offer consistent dosing; bulk dried herbs are more economical for regular use. Avoid very cheap, unlabelled products — quality varies enormously.