Important Safety Information

If you have an untreated genital infection, get infections easily, or have certain cancers, don't use Mirena. Less than 1% of users get a serious pelvic infection called pelvic inflammatory disease (PID)... Continue below

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How a Mirena IUD Works

Mirena is an IUD that works in the uterus

  • Mirena® is placed in the uterus by a healthcare professional 

  • Mirena contains 52 mg of a single hormone called levonorgestrel, a type of progestin, that is often used in birth control pills

  • Because Mirena slowly releases a continuous low dose of levonorgestrel into your uterus, only small amounts of the hormone enter your bloodstream

How does Mirena work to prevent pregnancy?

The hormone released into your uterus by Mirena prevents pregnancy most likely by:


  • Thickening cervical mucus, preventing sperm from entering the uterus

  • Inhibiting sperm movement so it’s more difficult to reach and fertilize an egg

  • Thinning the lining of your uterus, making it less likely for an egg to attach to the uterus


It is not known exactly how these actions work together to prevent pregnancy.

Close-up view of what Mirena® may look like in the body

Common side effects of Mirena include:

  • Pain, bleeding or dizziness during and after placement. If these symptoms do not stop 30 minutes after placement, Mirena may not have been placed correctly. Your healthcare professional will examine you to see if Mirena needs to be removed or replaced.

  • Changes in bleeding. You may have bleeding and spotting between menstrual periods, especially during the first 3 to 6 months. Sometimes the bleeding is heavier than usual at first. However, the bleeding usually becomes lighter than usual and may be irregular. Call your healthcare professional if the bleeding remains heavier than usual or increases after it has been light for a while.

  • Missed menstrual periods. About 2 out of 10 women stop having periods after 1 year of Mirena use. If you have any concerns that you may be pregnant while using Mirena, do a urine pregnancy test and call your healthcare professional. If you do not have a period for 6 weeks during Mirena use, call your healthcare professional. When Mirena is removed, your menstrual periods should return.

  • Cysts on the ovary. Some women using Mirena develop a painful cyst on the ovary. These cysts usually disappear on their own in 2 to 3 months. However, cysts can cause pain and sometimes cysts will need surgery.


Other common side effects of Mirena include:

  • abdominal or pelvic pain

  • inflammation or infection of the outer part of your vagina (vulvovaginitis)

  • headache or migraine

  • vaginal discharge


These are not all of the possible side effects with Mirena. For more information, ask your healthcare professional. 

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Mirena and HMB

Mirena is also approved to treat heavy menstrual bleeding for up to 5 years, in women who choose an IUD for birth control. See how Mirena works to treat heavy periods.



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What to expect

Get the lowdown on getting a Mirena IUD.

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Paying for Mirena

Insured or not, discover your options for getting Mirena.

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Facts about IUDs

Find answers to frequently asked questions about IUDs.

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Mirena® (levonorgestrel-releasing intrauterine system) is a hormone-releasing IUD that prevents pregnancy for up to 7 years. Mirena also treats heavy periods for up to 5 years in women who choose intrauterine contraception.



  • If you have an untreated genital infection, get infections easily, or have certain cancers, don't use Mirena. Less than 1% of users get a serious pelvic infection called pelvic inflammatory disease (PID).
  • If you have persistent pelvic or stomach pain, or excessive bleeding after placement, tell your healthcare professional (HCP). If Mirena comes out, call your HCP and avoid intercourse or use non-hormonal back-up birth control (such as condoms or spermicide). Mirena may go into or through the wall of the uterus and cause other problems.
  • Pregnancy while using Mirena is uncommon but can be life threatening and may result in loss of pregnancy or fertility.

  • Ovarian cysts may occur but usually disappear.
  • Bleeding and spotting may increase in the first 3 to 6 months and remain irregular. Periods over time usually become shorter, lighter, or may stop.


Mirena does not protect against HIV or STIs.


Only you and your HCP can decide if Mirena is right for you. Mirena is available by prescription only.


For important risk and use information about Mirena, please see Full Prescribing Information.