Risks

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:

• Headache
• Acne
• 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