English Name: knotgrass, polygonum
Pharmaceutical Name: Herba Polygoni Avicularis
Medica Category: Water-Regulating and Damp-Resolving Herbs
Properties: Bian Xu enters the Urinary Bladder channel; it is bitter in nature and cool in temperature.
The Chinese Herb Bian Xu is the dried aerial parts of common knotgrass (Polygonum aviculare L.), a plant related to the docks (a widespread tribe of broad-leaved wayside weeds) that grows along the ground in fields, gardens, and disturbed areas. It flowers in the summer and into the autumn, and it is at this time that the plant is gathered/harvested and dried for use as medicine.
Bian Xu clears damp-heat and promotes urination to treat lin zheng (dysuria syndrome) with heat and accumulated dampness (characterized by burning, painful sensations while urinating). This herb also addresses blood in the urine as well as urethral stones.
Bian Xu (vinegar-fried) kills parasites, notably roundworm and hookworm.
Bian Xu (topically) addresses anal itching (from parasites) as well as genital itching. Taken internally or used externally, it addresses damp-heat skin conditions (e.g. oozing sores, tinea)
**safety note—this herb has a diuretic effect and should be used with caution/under supervision of a trained TCM practitioner when combined with pharmaceutical medications that have diuretic effects (such as chlorothiazide, hydrochlorothiazide, furosemide (Lasix), bumetanide (Bumex), and torsemide (Demadex)) to avoid potentially excessive loss of fluids and/or electrolytes.