Folium Isatidis is bitter, salty and cold, enters the heart, lung and stomach meridians, and has the effects of clearing away heat and toxic materials, cooling blood and eliminating spots. Folium Isatidis is mainly used for: 1. Heat enters the blood, while warm toxin produces spots. This taste is bitter and cold, and it is good at relieving excess heat and toxic substances in the heart and stomach meridians. Salty cold enters the blood and can cool the blood and remove spots. Therefore, it can be used to treat diseases such as heat entering the blood, excessive toxicity in the heart and stomach, burning of both qi and blood, and spotting due to warm toxicity. It can also be used to treat exterior syndrome of wind-heat syndrome, initial febrile disease, fever, headache, thirst and sore throat. 2. Folium Isatidis has sore throat, aphtha, erysipelas and bitter cold, which can clear heart and stomach fire, and is good at removing toxins caused by epidemic diseases, and has the effect of detoxifying and relieving sore throat. "Bielu" contains Banlangen's "Treating Headache, Fever and Mouth Ulcer" and "Herbal Zheng Zheng": "Treating febrile diseases, wind-heat macula, carbuncle swelling and pain, removing polydipsia, stopping epistaxis and vomiting blood ... Anyone who is toxic at the same time should use green leaves to pound juice." Compendium of Materia Medica says it "cures dysentery, jaundice, laryngitis and erysipelas."