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Aster (zi wan)

What is aster? What is it used for?

Aster is an average-sized perennial plant native to east Asia. It blooms in September in October, and flourishes in sunny areas with moist, wet soils. In China, aster is produced predominantly in the Hebei and Anhui provinces. It is usually harvested in the spring or autumn, with the root used for medicinal purposes.

Aster root is purple and stringy, and resembles a pile of spaghetti in appearance. The roots are braided after being plucked, and allowed to dry in the sun. After being dried, they are usually cut into thick slices. Raw aster root is sometimes fried with honey before use. Aster root contains many chemicals that act as expectorants, along with a volatile oil.

Aster root is considered bitter and warm according to traditional Chinese medicine principles, and is associated with the Lung meridian. Its strongest functions are to relieve cough and expel phlegm, although it is also used to moisten the lungs and redirect qi. Today, aster root is used to treat violent, phlegmy coughs and other respiratory conditions, and to relieve pulmonary abscesses. Aster root is typically used in combination with platycodon and fritillaria to help stop coughs and get rid of phlegmy obstructions.

How much aster should I take?

The typical dosage of aster root is 3-9 grams per day, decocted in water for oral use. Some practitioners may recommend a slightly higher dose (5-10 grams).

What forms of aster are available?

Raw aster root (fried with honey) can be found at many Asian markets and herbal shops. Dried, sliced aster root is available at some specialty stores, as are aster tablets, powders and decoctions.

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

While there are no accounts of any adverse effects associated with taking too much aster root, it should be used with caution by patients experiencing excessive heat syndrome. As of this writing, there are no known drug interactions with aster root. As always, make sure to consult with a licensed health care provide before taking aster root or any other herbal remedy or dietary supplement.


  • Lu YH, et al. The chemical composition of zi wan. Journal of Pharmacy University of China 1998;29(2):97-99.
  • Zhang JM, et al. The chemical composition of huizhi zi wan (aster poliothamnus Diels). Journal of Chinese Medicine 1997;22(2):103-104.
  • He L, et al. The chemical composition of xiaoshe zi wan (aster albescens). Journal of Chinese Medicine 1996;21(8):483-484.
  • Zhao XG, et al. Zi wan (III): A comparison of the herb's expectorant and antitussive effects among different origins. Journal of Chinese Materia Medica 1999;30(1):353-7.
  • Li Y, et al. The effect of zi wan and gan cao on the trachea in guinea pigs. Chinese Medicine Information 1999;16(4):47.
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