Dangyao (Swertia, "Hepatitis Herb") and Dangfei Ligan Ning Tablets, a Good Liver Medicine

Dangyao is an uncommon Chinese herbal medicine, the dried whole herb of Swertia tosaensis (Gentianaceae). Because it bears purple flowers, it is also called Zihuadi dang. Dangyao was originally a folk herb used by Mongolians, who call it digeda; in Mongolian "digeda" means bitter—a name that aptly describes its taste. It is recorded in the Inner Mongolia Chinese Herbal Medicine.

Dangyao is mainly produced in China, Korea, Japan, and Russia. In China, besides Inner Mongolia and the Northeast, it is also found in North and Northwest China. It grows at Jinshan and Xishan in Haidian District, Beijing, at Baihuashan in Mentougou District, and in Huairou; it is also found in Chengde, Hebei, and Longxi, Gansu.

Dangyao clears damp-heat and strengthens the stomach. It is mainly used for jaundice due to damp-heat, hypochondriac pain, dysentery with abdominal pain, and poor appetite. Modern pharmacological studies show that this herb has good anti-hepatitis and anti-liver-fibrosis effects and lowers transaminases, hence its other name, "hepatitis herb." Contemporary hepatology expert Professor Yao Xixian found in clinical practice that combining Dangyao with Chishao (Red Peony) and Xihonghua (Saffron) has a good effect in lowering transaminases and preventing liver necrosis.

Fresh Dangyao is not easy to buy at ordinary pharmacies because it is not a common herb; most TCM pharmacies or hospital dispensaries around the country do not stock it. It can be self-harvested, and some online shopping platforms sell it, but I find it hard to distinguish genuine from fake.

Patients who can self-harvest Dangyao may do so; the usual decoction dose is 3-6 g daily. Because Dangyao has reliable efficacy in liver disease, modern pharmaceutical companies have made it into a ready-made medicine; patients who cannot harvest it may directly buy patent Chinese medicines containing Dangyao.

Dangfei Ligan Ning Tablets and Dangfei Ligan Ning Capsules, made from Dangyao combined with silybin, are commonly used patent Chinese medicines for treating hepatitis B, jaundice hepatitis, and abnormal liver function. Dangfei Ligan Ning clears and drains damp-heat, protects the liver and promotes bile, and relieves jaundice. It is mainly used for jaundice due to damp-heat stagnation, presenting as yellowing of the face or eyes, bitter mouth and dark urine, reduced intake and fatigue, or acute and chronic hepatitis with these patterns. Dangfei Ligan Ning may also be used as adjunctive therapy for cirrhosis, liver cancer, and liver damage.