YAZ is a combination birth control pill. A "combination" pill means that it is made up of more than one major ingredient. Nearly all birth control pills are made up of a combination of estrogen and progestin hormones. Estrogens are steroid hormones produced by the ovaries responsible for the typical female features. Progestins are steroid hormones produced by the ovary and placenta responsible for making the uterus fit for pregnancy. YAZ also contains an estrogen called ethinyl estradiol, and a progestin called drospirenone. People who develop acne have sebaceous glands that are over-stimulated (that is, the sebaceous glands have increased activity) by male sex hormones (androgens). The progestin in YAZ blocks the male sex hormones (androgens) that cause acne.