Ocella is a combined oral contraceptive
-- a birth control pill
that contains an estrogen and a progestin. It prevents pregnancy primarily by stopping ovulation (the maturation and release of eggs from the ovaries). However, it also prevents pregnancy in two other minor ways. Ocella alters the cervical mucus (the fluid of the cervix, which is the lower, narrow part of the uterus that is connected to the vagina), making it more difficult for sperm to enter the uterus. Lastly, this contraceptive alters the lining of the uterus (the endometrium), making it less receptive to an embryo.
Ocella is different from traditional birth control pills in an important way. The progesterone that it uses (drospirenone) is closely related to spironolactone
, a medication used as a diuretic ("water pill"). Drospirenone has anti-androgenic activity, which means that it works against testosterone and other "male" hormones. All women have a small amount of these "male" hormones that can cause acne and other problems. Also, drospirenone may increase the level of potassium in your blood, which can be a problem for some women.
Ocella was shown to be an effective birth control method in a large clinical trial. In this study, for every 100 women who used the drug for a year, fewer than one became pregnant. This is highly effective, compared to many other methods of contraception. For instance, as many as 14 percent of women using condoms for a year will become pregnant.