Blackend Swallowwort Root (Bai Wei)

Blackend Swallowwort Root (bai wei, 白薇), also known as Radix Cynanchi, refers to the root and rhizome of Cynanchum atratum or Cynanchum versicolor, which are perennial herbs belonging to the Asclepiadaceae family. Bai Wei first appeared in historical records in the late Western Han Dynasty (about 100 BC), as recorded in The Divine Farmer’s Materia Medica (Shen Nong Ben Cao Jing, 神农本草经).

During spring and autumn, people will gather the roots and rhizomes of Cynanchum atratum or Cynanchum versicolor, remove the impurities on them, wash them in water, dry them under the sun, and cut them into thin slices for medicinal usage. Brownish-yellow Bai Wei that has a yellow-white cross section, yellow heartwood and a light odour is preferred for medicinal usage.

In Traditional Chinese Medicine (TCM), Bai Wei falls under the category of ‘Herbs that clear Heat and dry Dampness’. Such herbs can clear inflammatory and infectious conditions, referred to as ‘Internal Heat’ in TCM. Cold in nature, Bai Wei can help individuals who have too much Heat in their body, such as those experiencing a Yang Excess or a Yin Deficiency, to restore a harmonious yin-yang balance.

Bitter and salty in taste, Bai Wei can cleanse the body by clearing Heat, drying Dampness and promoting elimination via urination or bowel movements. Also, Bai Wei has a draining effect on the body by clearing accumulations, removing phlegm and softening hard lumps. In particular, Bai Wei targets the Kidneys, the Liver and the stomach.

Traditional Chinese Medicine (TCM) shows that Bai Wei has the following health benefits.

Bai Wei can cool one’s blood and clear Heat in one’s body. For example, Bai Wei can relieve Yin Deficiency, Summer-Heat with fever among children, lingering fever that has injured one’s blood or yin, recovery from febrile diseases and post-partum fever. 

Also, Bai Wei can promote urination, which helps to treat hot, bloody or painful urinary dysfunctions such as urinary tract infections, especially before or after giving birth.

In addition, Bai Wei can relieve toxicity and treat sores. For example, the herb is used for toxic sores, swollen and painful throat, and even snake bites. Bai Wei can be used internally or topically to treat such symptoms.

The recommended daily dosage of Bai Wei is 4.5 – 9g, when used as a decoction.

Bai Wei and its supplements, such as powder and pills, can be found in herbal stores and Asian specialty markets.

Bai Wei should not be used by individuals experiencing diarrhoea or those who are not experiencing Heat signs. Also, individuals who are experiencing poor appetite, Spleen and Stomach Deficiency should avoid this herb too. Some side effects associated with the overconsumption of Bai Wei include nausea, vomiting, palpitations, dizziness, headache and diarrhoea.

Do note that Bai Wei should not be taken together with Radix Astragali Membranacei (Huang Qi), Radix et Rhizoma Rhei (Da Huang), Japanese Thistle (Da Ji), Rhizoma Zingiberis Officinalis (Gan Jiang) or Frucutus Corni Officinalis (Shan Zhu Yu).

Here is a summary for Blackend Swallowwort Root (Bai Wei):

• Herb name (Chinese): 白薇
• Herb name (Pin Yin): bái wēi
• Herb name (English): Blackend Swallowwort Root
• Herb name (Botanical): Radix et Rhizoma Cynanchi Atrati
• Origin of species: Cynanchum atratum Bge.; Cynanchum versicolour Bge.
• Part(s) of herb used: Rhizome and Root
• Geo-specific habitat(s): Northern and southern parts of China
• Taste(s) & Properties: Bitter, salty; Cold; Administrates the Stomach, Liver and Kidney Meridians
• Actions: Helps to relieve hot flushes, night sweating or fever after giving birth; Provides relief for painful sore throats; Aids urination, relieve painful urination; Eases inflammatory conditions

Li, X. (2015). Research on curative effect of traditional Chinese medicine treating low-grade fever of children caused by respiratory system infection. Pakistan Journal of Pharmaceutical Sciences, 28. [Accessed on 5th June 2023]

Zhao, Z., Liang, Z., & Ping, G. (2011). Macroscopic identification of Chinese medicinal materials: traditional experiences and modern understanding. Journal of ethnopharmacology, 134(3), 556-564.[Accessed on 5th June 2023]