Liuwei Dihuang Pill is a modified version of Qian Yi's general plan in Song Dynasty. Its main function is to improve human immunity and protect liver and kidney. Because liver and kidney are the largest detoxification organs of human body, kidney is the congenital foundation and the source of human vaginal fluid. Therefore, caring for the kidney can prolong life and beautify the body, but six flavors are a good medicine for tonifying kidney and nourishing yin. People with kidney-yang deficiency are not suitable for taking this medicine, and it is toxic in three ways. You'd better listen to the doctor when taking it.