Deng Xin Cao
Deng Xin Cao
By Eric Brand
Pictured above is the official medicinal form of Deng Xin Cao, a key agent in formulas for painful urination such as Dao Chi San. Deng Xin Cao is the pith of juncus, and it looks like a little white strip of styrofoam.
The item that most of us are familiar with as Deng Xin Cao is not actually the official item in the Chinese Pharmacopoeia, but rather a regional market variation. The item that is most common in trade in the West is a long bundle of grass that is tied together by the grass itself and wrapped in the little white pith. This item is the whole herb of juncus, tied into bundles and wrapped in Deng Xin Cao, the pith. The use of the whole herb plus pith is common in the south of China, and it is the item often dispensed as Deng Xin Cao in Hong Kong, Taiwan, and the West.
Recently I got a call from a friend who works at a school clinic, and they had been having a vigorous debate on what the real Deng Xin Cao is. What Deng Xin Cao is often depends on where you live and how much you pay. In the north of China, the pure pith is often used, and the pith (as pictured above) is the item listed in the Chinese Pharmacopoeia as the official drug. In southern regions where the weather is warm and the king is far, the item used is generally the whole plant. Today, both forms are regarded as acceptable forms of the medicinal, and the whole plant is regarded as a regional variant rather than an adulterant.
One of my teachers from Sichuan had a very interesting use for Deng Xin Cao. She would take the white stryrofoam-like portion and she would light it on fire. She would then extinguish it by pressing it on the body, often for the treatment of herpes zoster. Deng Xin Cao can also be charred and sprayed into the throat to treat throat impediment (severe sore throat with blockage).