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Knoxia Root (hong da ji)

What is knoxia root? What is it used for?

Knoxia is a type of plant related to the euphorbia plant. Although it is native to Japan, it now grows throughout Asia. In China, it is grown mainly in the Shanxi, Shandong, Jiangsu, Sichuan and Guangxi provinces, and harvested twice a year (at the beginning of spring and the end of autumn).

Knoxia root is prepared by digging up the plant, removing any extra stems or fibrous material from the root, and allowing it to dry in the sun. It can be used either raw or processed with vinegar, and taken either internally or externally.

In traditional Chinese medicine, knoxia root is considered bitter, pungent and cold, and is associated with the Lung, Kidney and Large Intestine meridians. Its functions are to reduce swelling and resolve masses, and to arrest water retention. Knoxia root is used to treat edema and fluid retention on the face and body, and to treat surface infections on the skin. Fresh herb is used for external applications.

How much knoxia root should I take?

The typical dose of knoxia root is between 1.5 grams and 3 grams, taken either as a pill or powder. Larger amounts can be used if it applied topically. It should be prepared with vinegar to reduce its toxicity.

What forms of knoxia root are available?

Fresh knoxia root can be found at some Asian markets. Knoxia is also available in pill, powder and extract form.

What can happen if I take too much knoxia root? Are there any interactions I should be aware of? What precautions should I take?

Knoxia is considered extremely toxic. It should not be taken by women who are pregnant or breastfeeding, or patients with weak constitutions. It counteracts the effects of licorice, and should not be taken with any formulas that contain licorice. As of this writing, there are no known drug interactions with knoxia root. As always, make sure to consult with a licensed health care provider before taking knoxia root or any other herbal remedy or dietary supplement.


  • Knoxia root. database. Available online
  • Knoxia root. Herbasin Chinese herb database. Available online.
  • Knoxia root. database. Available online.
  • Knoxia root. database. Available online.
  • Wang XF, Chen JY, Lu WJ. Studies on the chemical constituents of knoxia valerianoides thorel ex petard. Yao Xue Xue Bao August 1985;20(8):615-8. In Chinese.
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