世人谈外丹,通常的反应是外丹有毒,并喜欢援引清代赵翼《廿二史札记》记载,称仅唐代皇帝死于服丹者即有六人,大臣死于此者更多。由此指出盛唐以后外丹渐趋衰微。不可否认,金属丹药有毒副作用,但是它们也有一定疗疾治病 When the world talks about Waidan, the usual reaction is that the poison is extravagant, and he likes to quote Zhao Wei’s “Notes on the History of the Second Annals of the Qing Dynasty” in the Qing Dynasty. He said that only the Tang Dynasty emperor had died when he served Dan, there were six people, and ministers died there were more. . It is thus pointed out that after the Tang Dynasty, the outer dan gradually declined. It is undeniable that metallic dan drugs have toxic side effects, but they also have a certain cure.