English Name: indigo
Pharmaceutical Name: Indigo Naturalis
Medica Category: Heat-Clearing and Toxin-Eliminating Herbs
Properties: Qing Dai enters the Liver, Lung, and Stomach channels; it is salty in nature and cold in temperature.
The Chinese Herb Qing Dai is a powder called indigo naturalis (so as to distinguish it from other forms/preparations of indigo that are used as dyes). Indigo naturalis comes from several different species of leaves from plants in the woad (Brassicaceae) family (including Isatis tinctoria L., the same species that gives us Ban Len Gen and Da Qing Ye). These leaves are collected in the autumn when they fall to the ground and are soaked overnight in water. Natural enzymes are then added to this solution so that it changes color and character; the solution is then evaporated away and what is left is the medicinal substance Qing Dai (or indigo naturalis).
Qing Dai clears heat at the xue (blood) level when heat is forcing the blood out the vessels (to treat such clinical presentations as macula, pupura, hematemesis (vomiting up blood), and epistaxis (nosebleeds)).
Qing Dai clears heat from the Lung to address clinical presentations such as cough with thick yellow sputum and dyspnea.
Qing Dai clears heat and eliminates toxins and is often used (in formula) to treat childhood convulsions and convulsions in adults when accompanied by heat signs and delirium.