What Hormone Does Mirena Have?

When considering a contraceptive, many women consider an IUCD (Intrauterine Contraceptive Device). Mirena is one such device, and is used by many women as a means to prevent pregnancy. If you are considering Mirena, it is important to know what it contains and how it works, as well as the pros and cons of using Mirena.


Mirena is a contraceptive that releases a hormone called Levonorgestrel, a hormone that effectively prevents pregnancy. Mirena is an IUCD that is placed in the womb of a woman and left there for up to five years; it is "T" shaped and is inserted by a doctor in an outpatient office visit. The Mirena IUCD holds a supply of Levonorgestrel to be distributed in tiny proportions directly to the lining of the uterus.


Levonorgestrel, the hormone that Mirena distributes while in the uterus, prevents pregnancies in a couple of ways; it can make the lining of the uterus extremely thin, which prevents eggs from being implanted, and for some women, it even prevents ovulation. Levonorgestrel can also work by thickening the mucus at the base of the uterus to prevent sperm from entering to fertilize any eggs that may implant in the uterine wall. For some women, only one of the prevention methods occur, while some women experience all three methods.

Time Frame

If it is fitted properly and at the correct time, Mirena is known to be effective for up to five years; after this time it must be changed or removed. It is recommended that this IUCD be inserted within a week before starting your period, or six weeks after delivering a baby; it may also be inserted soon after the termination of a pregnancy.


Two million women in the United States have chosen Mirena as their contraceptive choice and it is 99% effective in preventing pregnancy among its users. Mirena is proving to be a very useful IUCD for even non-contraceptive uses; it can decrease the amount of blood lost and length of periods in women, so it is used (like other birth controls are for different purposes) as a treatment for extremely heavy periods. Mirena can also reduce the symptoms of PMS by bypassing the blood stream and being distributed directly to the uterus lining. Mirena is even used as a hormone replacement therapy in some cases.


Though there are many benefits of using Mirena, there are a few negative effects, including an increased risk of hypertension and gall bladder disease. For some women, other problems may occur such as respiratory conditions, dizziness, headaches and skin conditions. If Mirena should fail to work, ectopic pregnancies can result. Talk with your doctor about the pros and cons of using Mirena as a contraceptive. Mirena is meant to prevent pregnancies, not to prevent the spread of STDs.