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What Is Mirena®


Mirena (levonorgestrel-releasing intrauterine system) is an intrauterine contraceptive that delivers small amounts of hormone directly to the uterus. Made of soft, flexible plastic, it is put in place by your healthcare provider during an office visit. Mirena is birth control that lasts as long as you want, for up to 5 years, and is also approved to treat heavy periods in women who choose intrauterine contraception. Mirena works continuously, without having to take a pill, without a daily hassle. Once Mirena is properly placed, all you have to do is check the threads once a month. Your healthcare provider can show you how. If you have trouble finding the threads, be sure to use a backup form of birth control and call your healthcare provider.


  • Offers an over 99% effective form of contraception, among the most effective forms of birth control
  • Prevents pregnancy for as long as you want, for up to 5 years
  • Allows you to try to become pregnant as soon as it is removed by your healthcare provider.*
  • Treats heavy periods:
    • In a clinical trial of women with heavy periods, the majority treated with Mirena showed a reduction in bleeding of more than 90% at 6 months.

* A woman’s chances of getting pregnant within 12 months of having Mirena removed are approximately 80%

How Mirena® Works

Mirena (levonorgestrel-releasing intrauterine system) slowly releases very small amounts of the hormone levonorgestrel directly into your uterus.

There is no single explanation for how Mirena works. Mirena may:

  • Thicken cervical mucus to prevent sperm from entering your uterus
  • Inhibit sperm from reaching or fertilizing your egg
  • Make the lining of your uterus thin

Mirena may stop the release of your egg from your ovary, but this is not the way it works in most cases. Most likely the above actions work together to prevent pregnancy. Like other forms of birth control, Mirena is not 100% effective


Mirena is a tiny T-shaped piece of soft, flexible plastic that is placed in the uterus by your healthcare provider during an office visit. It’s designed to be small and comfortable, so that you and your partner most likely won’t even feel like it’s there

Mirena keeps hormone levels steadier and lower than the Pill.

When should Mirena® be placed

Mirena should be placed within 7 days of the start of your period. When properly placed, Mirena prevents pregnancy for as long as you want for up to 5 years.

Will placement hurt

Some women may experience some discomfort while Mirena is being placed. Side effects may include cramping or pain, bleeding and/or dizziness. This is common. Let your healthcare provider know if the cramping is severe.

What can I expect right after Mirena® is placed

Some women may experience cramping or pain, bleeding, and/or dizziness during and right after Mirena is placed. Tell your healthcare provider if your cramps are severe. To help minimize the cramps, ask your healthcare provider about medications that may be used before placement. If these symptoms last for more than 30 minutes, let your healthcare provider know. Mirena may not have been properly placed and your healthcare provider should examine you.

Will my periods change with Mirena®

For the first 3 to 6 months, your monthly period may become irregular. You may also have frequent spotting or light bleeding. A few women have heavy bleeding during this time. Call your healthcare provider if the bleeding remains heavier than usual. After your body adjusts, the number of bleeding days is likely to decrease, but may remain irregular, and you may even find that your periods stop altogether for as long as Mirena is in place

Around the end of the third month of use, you may see up to a 75% reduction in the amount of menstrual bleeding.1 Call your healthcare provider if the bleeding becomes heavy after it has been light for a while.

By one year, about 1 out of 5 users may have no period at all. Your periods will return once Mirena is removed. If, after the start of your last period, you go 6 weeks without another period, contact your healthcare provider to rule out pregnancy.

Can Mirena® protect me from HIV or STDs (sexually transmitted diseases)

No. Mirena does not protect against HIV or STDs. So, if while using Mirena you think you or your partner might be at risk of getting an STD, use a condom and call your healthcare provider.

What if I decide I want to try to get pregnant

Mirena prevents pregnancy for as long as you want, for up to 5 years. When you decide you want to try to have another child, Mirena can be removed by your healthcare provider at any time. It typically takes just a few minutes during an office visit. After that, you can begin trying to get pregnant right away. A woman’s chances of getting pregnant within 12 months of having Mirena removed are approximately 80%.

What happens if I do get pregnant while using Mirena®

Unfortunately, no birth control method, including Mirena or even getting your tubes tied, is 100% perfect. If you do get pregnant while using a birth control method, there can be risks to you and your baby

Less than 8 in 1,000 women become pregnant over the course of the five years using Mirena. One risk of getting pregnant using Mirena is called ectopic pregnancy, when the pregnancy is not in the uterus. It may occur in the fallopian tubes. Signs of ectopic pregnancy may include unusual bleeding or abdominal pain. Ectopic pregnancy is an emergency that requires immediate medical attention and often surgery. Ectopic pregnancy can cause internal bleeding, infertility and even death. Call your healthcare provider right away if you think that you’re pregnant.

There are also risks if you get pregnant while using Mirena and the pregnancy is in the uterus. Severe infection, miscarriage, premature delivery and even death can occur with pregnancies that continue with an intrauterine device (IUD). Because of this, your healthcare provider may try to remove Mirena, even though removing it may cause a miscarriage. If Mirena cannot be removed, talk with your healthcare provider about the benefits and risks of continuing the pregnancy


Only you and your healthcare provider can decide if Mirena is right for you. Mirena is recommended for women who have had a child.

  • Don’t use Mirena if you have a pelvic infection, get infections easily or have certain cancers. Less than 1% of users get a serious infection called pelvic inflammatory disease. If you have persistent pelvic or abdominal pain, see your healthcare provider.
  • Mirena may attach to or go through the wall of the uterus and cause other problems. If Mirena comes out, use back-up birth control and call your healthcare provider.
  • Although uncommon, pregnancy while using Mirena can be life threatening and may result in loss of pregnancy or fertility.
  • Ovarian cysts may occur and usually disappear.
  • Bleeding and spotting may increase in the first few months and continue to be irregular. Periods over time may become shorter, lighter or even stop.

For more information on Mirena please visit www.mirena-us.com

*The recommendations and information provided by this Web site are for educational purposes only. This Web site does not contain comprehensive coverage of the topics addressed, and is not a substitute for direct consultation with your health care provider. Always consult a health care provider regarding your specific condition. Trademarks referred to are the property of their respective owners.

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