Mirena is an intrauterine device (IUD) that is used to prevent pregnancy and to treat heavy menstrual bleeding. Mirena is inserted into your uterus by your health care provider. It may be used to prevent pregnancy for up to eight years. When used to decrease heavy menstrual bleeding and to prevent pregnancy, Mirena must be removed after five years.
How Does Mirena Work for Birth Control?
Mirena is a small, flexible plastic, T-shaped system that slowly releases small amounts of a progestin hormone (levonorgestrel) into your uterus. It is the same hormone used in many birth control pills. It prevents pregnancy by thickening the mucus in your cervix to block sperm from reaching the uterus, affecting sperm so they cannot survive or function properly. It also causes thinning in the lining of your uterus, which can cause your menstrual bleeding to be less and make it less likely for a pregnancy to happen.
How Do I Use Mirena?
Mirena is a hormone-releasing system placed in your uterus by your health care provider during an office visit or right after you have a baby.
There are two thin threads attached to the lower end of Mirena. You can feel these threads when Mirena is in your uterus, but they do not extend outside of your body. You will need to do a thread check once a month to make sure Mirena is still in place. Your health care provider will teach you how to do this. Within four to six weeks of Mirena placement, you will have a follow-up visit with your health care provider to make sure Mirena is in the correct place.
If you do not feel the threads or feel more than threads, call your health care provider because Mirena might not be in the right position and may not prevent pregnancy. Avoid intercourse or use a backup birth control method, such as condoms, until your health care provider can check that Mirena is in the right place.
Mirena may be removed by your health care provider at any time but must be removed after eight years. If you are using Mirena for heavy menstrual flow, after five years your health care provider can remove and place a new Mirena during the same office visit.
You can become pregnant as soon as Mirena is removed. If you do not want to become pregnant, talk to your health care provider about other birth control methods. Your new method may need to be started seven days before Mirena is removed to prevent pregnancy.
How Was Mirena Studied for Pregnancy Prevention and What Did the Studies Find?
For prevention of pregnancy, Mirena was studied in two clinical trials in Finland and Sweden. The studies included 1,169 women between 18 and 35 years old who used Mirena for up to five years. About 5.6% of people in the study had never been pregnant before. The people in the study had no history of ectopic pregnancy, no pelvic inflammatory disease in the prior 12 months, and most (70%) had used IUDs in the past. The five-year pregnancy rate was about 0.7 per 100 women (0.7%). This means that less than 1 in 100 women became pregnant over 5 years.
The Mirena Extension Trial (MET) was completed to see if Mirena was safe and effective for preventing pregnancy for up to eight years. The study included 362 people in the United States between 18 and 35 years old who were current users of Mirena for 4.5 to five years and were willing to continue using it for up to eight years. Those with a known or suspected pregnancy, abnormal cervical smear, menopause symptoms and FSH (follicle stimulating hormone) levels greater than 30 mIU/mL, unexplained or abnormal bleeding, infection, cancer, immune deficiency, or substance abuse were not included in the study.
In the study, 75% were White, 14% were Black/African American, 2.5% were Asian, and 11.3% were Hispanic. The average weight was 75.6 kg (about 167 pounds), the average body mass index (BMI) was 27.9 kg/m2 (overweight), and about 47% of women had never given birth to a child.
The main outcome of the study was the occurrence of pregnancy within years six to eight of Mirena use. There were two pregnancies in years six to eight. Mirena was more than 99% effective at preventing pregnancy for up to eight years.
Your results may differ from what was seen in clinical studies.
What Should I Expect When Starting Mirena?
After Mirena is inserted into your uterus, it takes about seven days for it to start working as pregnancy prevention. For the first three to six months, your menstrual period may become irregular, and the number of bleeding days may increase. You might have spotting or light bleeding, and some people might have heavy bleeding. You may also have cramping during the first few weeks. Over time, the number of bleeding and spotting days will lessen. In some people, periods will stop. When Mirena is removed, menstrual periods return.
In some people with heavy bleeding, the amount of blood loss with each menstrual cycle lessens as time goes on. The number of spotting and bleeding days may increase initially, but then usually lessens in the months that follow.
Is Mirena Right for Me?
Mirena is a long-term birth control method that is very effective at preventing pregnancy. It does not require a daily routine. Mirena can be removed if you want to become pregnant. It can be used whether or not you have ever had a baby. Mirena does not contain estrogen.
Do not use Mirena if:
- You are or might be pregnant. It cannot be used as emergency birth control.
- You have a pelvic infection called pelvic inflammatory disease (PID) or have had PID in the past.
- You have an untreated genital infection.
- You are at risk for infections: You have multiple sexual partners or your partner has multiple sexual partners; you have problems with your immune system; or you use or misuse intravenous drugs.
- You have cancer of the uterus or cervix.
- You have bleeding from your vagina from an unknown cause.
- You already have an IUD in your uterus.
- You have large fibroid tumors in your uterus.
- You have an allergy to levonorgestrel, silicone, polyethylene, silica, barium sulfate, or iron oxide.
What Are the Side Effects, and How Can I Manage Them?
The most common side effects seen with Mirena are changes in menstrual bleeding, stomach or pelvic pain, and headache.
Pain, bleeding, or dizziness may occur during and after Mirena is placed in your uterus. If these symptoms last longer than 30 minutes, Mirena might not have been placed correctly. Your health care provider will examine you to see if Mirena needs to be removed or replaced.
If you have stomach or pelvic pain or cramps, you can take an over-the-counter pain reliever like acetaminophen or ibuprofen. You can also place a heating pad or hot water bottle on your belly. If you have painful cramps, call your health care provider.
Call your health care provider right away if you think you might be pregnant. If you get pregnant while using Mirena, there is a chance that you may have an ectopic pregnancy. Signs of this are unusual vaginal bleeding or abdominal pain, especially with missed periods. Ectopic pregnancy is a medical emergency that may require surgery. It can cause bleeding, infertility, and death if not treated.
These are not all the possible side effects. Talk with your health care provider if you are having symptoms that bother you. If you experience anything that you think may be caused by Mirena, you can also report side effects to the FDA at 800-FDA-1088 (800-332-1088).
Is There Any Cost Assistance Available?
There is a cost savings and support program that may help you afford Mirena. Your health care provider will help you to get started with this program. For questions or more information, you can contact the drugmaker at 888-842-2937 or visit Mirena copay savings program.
