Common Knotgrass Herb

Source Knotweed is the whole plant of Polygonum aviculare L., (Fam. Polygonaceae.) without the roots.

Producing Areas All parts of China

Properties Bitter, Slightly Cold
Channels Gall Bladder


  • Promotes urination and dispels heat-dampness in the bladder
    For burning and painful urination.
  • Alleviates jaundice due to heat-dampness
  • Kills intestinal parasites and stops itching
    For roundworms, pinworms, hookworms, ringworms, and tapeworms.
    Also for tinea, eczema, and itching due to lesions on damp skin, and for oozing sores.
  • Treats bacterial dysentery

Usage and Dosage
9–15 g is used in decoction for oral use.
The amount of the fresh should be doubled.
The pounded fresh can be used for external application

Excessive use may damage essential qi.
Use with caution in the patient with deficiency of the soleen or without heat-damoness.

Keep in a ventilated and dry place.

Description of Quality Herb
The good one is tender and greyish green with many leaves.

Professional Tips

Identifying Bianxu and Qumai (Herba Dianthi):
Similarities: Both are important herbs for clearing heat, inducing diuresis and treating stranguria. They are often used together to treat oliguria with brownish urine. Both can treat heat-related sore and itching due to eczema.
Differences: Bianxu is for killing worms to stop itching. Qumai is for circulating the blood and dredging the channels.