The best medication for estrogen supplementation is estradiol. This hormonal drug, when entered into the body, can target the ovaries to stimulate the secretion of estrogen. Estradiol is a natural estrogen that can be absorbed through the digestive tract and is easily metabolized in the liver, and is best administered by injection. Estradiol can promote the development of the uterus, thymus enlargement, and the maintenance of secondary female sexual characteristics in underage women. It also causes the endometrium to proliferate and thicken in adult women, and together with progesterone, it transforms the endometrium into a secretory phase and increases the sensitivity of the uterine smooth muscle to contractile hormones, thereby forming the menstrual cycle. In addition, estradiol increases the deposition of calcium salts in human bones and accelerates epiphyseal closure. It can suppress the secretion of androgens in the body by supplementing estrogen. It is used to treat acne in adolescence, and can also be used to treat advanced breast cancer and prostate cancer.