The poison in Li Yuhang is a very secretive toxin, with a slow-acting medicinal nature. However, when the concentration of the toxin accumulates to a certain level, the human body will suddenly collapse. The symptoms of the poisoning resemble organ failure. It looks like an illness, but the cause of the illness cannot be found. With current medical technology, it can only be detected that the body's organs are gradually failing, but it cannot be detected that someone has administered poison.
A few years ago, when An Yiqing and Ye Chenghong went out as traveling doctors, they encountered someone who had been poisoned in this way. At that time, An Yiqing's skills were not enough, and it was Ye Chenghong who saved the life of the poisoned person. However, although An Yiqing did not take action to detoxify then, she learned Ye Chenghong's techniques completely.
