Mirena is a hormonal intrauterine device (IUD) that can provide long-term birth control (contraception).
The device is a T-shaped plastic frame that's inserted into the uterus, where it releases a type of the hormone progestin. To prevent pregnancy, Mirena:
- Thickens mucus in the cervix to stop sperm from reaching or fertilizing an egg
- Thins the lining of the uterus and partially suppresses ovulation
Mirena prevents pregnancy for up to five years after insertion. It's one of several hormonal IUDs with Food and Drug Administration approval.
Why it's done
Mirena offers effective, long-term contraception. It can be used in premenopausal women of all ages, including teenagers.
Among various benefits, Mirena:
- Eliminates the need to interrupt sex for contraception
- Doesn't require partner participation
- Can remain in place for up to five years
- Can be removed at any time, followed by a quick return to your normal fertility
- Can be used while breast-feeding — although your health care provider will likely recommend waiting six to eight weeks after childbirth because earlier placement increases the risk of injuring the uterus during placement
- Doesn't carry the risk of side effects related to birth control methods containing estrogen
Mirena can decrease menstrual bleeding after three or more months of use. About 20 percent of women stop having periods after one year of using Mirena.
Mirena can also decrease:
- Severe menstrual pain and pain related to the abnormal growth of uterine-lining tissue outside the uterus (endometriosis)
- The risk of pelvic infection
- The risk of endometrial cancer
Because of these noncontraceptive benefits, Mirena is often prescribed for women with:
- Heavy menstrual bleeding
- Cramping or pain with periods
- Abnormal growth of the lining of the uterus (endometrial hyperplasia)
- Abnormal growth of uterine-lining tissue into the muscular wall of the uterus (adenomyosis)
Mirena isn't appropriate for everyone. Your health care provider may discourage use of Mirena if you have:
- Breast cancer, or have had it
- Uterine or cervical cancer
- Liver disease
- Uterine abnormalities, such as fibroids, that interfere with the placement or retention of Mirena
- A pelvic infection or current pelvic inflammatory disease
- Unexplained vaginal bleeding
Tell your health care provider if you:
- Take any medications, including nonprescription and herbal products
- Have diabetes or high blood pressure
- Have a heart condition or have had a heart attack
- Have migraines
- Have blood-clotting problems or have had a stroke
- Recently gave birth or are breast-feeding
Less than 1 percent of women who use Mirena will get pregnant in a year of typical use.
If you do conceive while using Mirena, you're at higher risk of an ectopic pregnancy — when the fertilized egg implants outside the uterus, usually in a fallopian tube. However, because Mirena prevents most pregnancies, women who use it are at lower risk of having an ectopic pregnancy than are other sexually active women who are not using contraception.
Mirena is generally safe. But it's important to remember that:
- Mirena doesn't protect against STIs.
- Rarely, insertion of Mirena causes perforation of the uterus. The risk of perforation might be higher when inserted during the postpartum period.
Side effects associated with Mirena include:
- Breast tenderness
- Irregular bleeding, which can improve after six months of use
- Mood changes
- Cramping or pelvic pain
It's also possible to expel Mirena from your uterus. You may be more likely to expel Mirena if you:
- Have never been pregnant
- Have heavy or prolonged periods
- Have severe menstrual pain
- Previously expelled an IUD
- Are younger than age 20
- Had Mirena inserted immediately after childbirth
Your health care provider may recommend removal of Mirena if you develop:
- A pelvic infection
- Inflammation of the endometrium (endometritis)
- Endometrial or cervical cancer
- Pelvic pain or pain during sex
- Very severe migraine
- A significant increase in blood pressure, or have a stroke or heart attack
- Possible exposure to an STI
How you prepare
Your health care provider will evaluate your overall health and do a pelvic exam before inserting Mirena. You may be screened for STIs.
Mirena can be inserted:
- Anytime during your menstrual cycle if you're not pregnant. You might need to take a pregnancy test to confirm you're not pregnant.
- Immediately after a pregnancy termination.
- Immediately after delivering a baby vaginally or by cesarean section — although insertion immediately after vaginal delivery increases the risk of expelling Mirena.
If you have Mirena inserted more than seven days after the start of your period, be sure to use backup contraception for one week.
Taking a nonsteroidal anti-inflammatory medication, such as ibuprofen (Advil, Motrin IB, others), one to two hours before the procedure can help reduce cramping.
What you can expect
Mirena is typically inserted in a health care provider's office.
During the procedure
Your health care provider will insert a speculum into your vagina and clean your vagina and cervix with an antiseptic solution. Special instruments might be used to gently align your cervical canal and uterine cavity and to measure the depth of your uterine cavity.
Next, your health care provider will fold Mirena's horizontal arms and place the device inside an applicator tube. The tube is inserted into your cervical canal, and Mirena is carefully placed in your uterus. When the applicator tube is removed, Mirena will remain in place.
Your health care provider will trim Mirena's strings so that they don't protrude too far into the vagina, and may record the length of the strings.
During Mirena insertion, you may experience cramping, dizziness, fainting or a slower than normal heart rate.
After the procedure
Once a month, check to feel that Mirena's strings are protruding from your cervix. Be careful not to pull on the strings.
About a month after Mirena is inserted, your health care provider may re-examine you to make sure Mirena hasn't moved and to check for signs and symptoms of infection.
While you're using Mirena, contact your health care provider immediately if you:
- Think you may be pregnant
- Have unusually heavy, persistent vaginal bleeding
- Have abdominal pain or pain during sex
- Have an unexplained fever
- Have unusual or foul-smelling vaginal discharge, lesions or sores
- Develop very severe headaches or migraines
- Have yellowing of the skin or eyes
- Were exposed to an STI
- Can no longer feel the IUD strings, or they suddenly seem longer
It's also important to contact your health care provider immediately if you think Mirena is no longer in place. Your provider will check the location of Mirena and, if it's displaced, remove it if necessary.
Mirena can remain in place for up to five years. To remove Mirena, your health care provider will likely use forceps to grasp the device's strings and gently pull. The device's arms will fold upward as it's withdrawn from the uterus.
Light bleeding and cramping is common during removal. Rarely, removal can be more complicated.