Radix Isatidis (Isatis Root): Pharmacognosy and Uses

Name

Ban Lan Gen (Radix Isatidis), from Xin Xiu Ben Cao (Newly Revised Materia Medica)

Source and quality

The root of the biennial herbaceous plant Isatis indigotica Fort. of the family Cruciferae. It is produced in the Shaanxi, Hebei, Jiangsu, Zhejiang and Anhui provinces of China, and is collected in autumn.

It has a slight odor and is slightly sweet, bitter and astringent. The best grade has a straight, thick, even root with a solid body and enough mealiness. It is sliced and used unprocessed.

Nature and action

Bitter and cold. It enters the lung, stomach, heart and liver meridians.

It clears heat and removes toxicity, cools the blood and alleviates sore throat.

Indications

Warm disease and external contraction of wind-heat

Ban Lan Gen and Da Qing Ye come from the same plant, isatis, but the medicinal parts differ. They are similar in their properties and effects: both clear heat and purge fire when entering the qi system, and clear heat and cool the blood when entering the blood system. Both are widely indicated at every stage of warm disease and for the exterior syndrome of external contraction of wind-heat, and they are commonly combined together to treat mumps, erysipelas and fever with a swollen head due to warm-toxin, so that they reinforce each other.

Although its action of cooling the blood and removing macules is not as good as that of Da Qing Ye, Ban Lan Gen specializes in removing toxicity to relieve sore throat and reduce swelling, so it suits the early stage of warm disease or external contraction of wind-heat characterized by fever and sore throat.

• It is used in Gan Mao Tui Re Chong Ji from the Pharmacopoeia of the People's Republic of China published in 1990.
• It is often combined with herbs good at dispersing wind-heat to improve the effect, such as Bo He, Jin Yin Hua and Lian Qiao.
• For warm disease at the stage of dual blazing of both qi and blood, or heat entering the nutrient-blood level, manifested as high fever and macules, it clears heat and removes toxicity, cools the blood and removes macules, and it is often combined with other herbs that relieve toxicity and cool the blood, to clear heat from both the qi and blood systems: Huang Qin, Zi Cao and Sheng Di Huang in Shenxi Dan from Wen Bing Tiao Bian.

Swollen and sore throat

It is good at clearing the heart and removing toxicity, clearing heat from the lung and stomach to relieve sore throat and dissipate nodulation. It is commonly used for a red, swollen, sore throat and for red swelling and pain of both cheeks, all caused by interior excessive heat-toxin, attack by epidemic toxin, or wind-heat. It can be used on its own or combined with herbs that disperse wind-heat, remove toxicity and relieve sore throat, such as Niu Bang Zi, Xuan Shen and Jie Geng in Puji Xiaodu Yin from Dong Yuan Shi Xiao Fang (Dongyuan's Effective Prescription).

In addition, because it clears heat, removes toxicity and cools the blood, it also suits sores and swollen, painful abscesses, red eyes, and hematemesis and epistaxis due to blood heat.

Dosage and administration

Decoct 15~30 g, or 60~120 g as a large dose; it may also be made into pills or powder. A proper dose is used for topical application.