If you’re looking for a long-term birth control option, you may consider an intrauterine device (IUD). An IUD is a small, flexible, T-shaped device that’s placed in your uterus mainly to prevent pregnancy. There are two types of IUDs: a copper IUD that does not release hormones, and a plastic IUD that releases controlled doses of hormones.

Mirena is a brand-name IUD that releases the hormone levonorgestrel. Here’s what you need to know about Mirena to decide if it’s a good birth control option for you.

Mirena can be used to prevent pregnancy for up to five years. It can also be used to reduce heavy menstrual bleeding in women who also want birth control. Other brand-name IUDs that release levonorgestrel include Liletta, Skyla, and Kyleena.

Mirena contains 52 mg of levonorgestrel, a hormone that’s often used in birth control pills. The device releases roughly 20 mcg of levonorgestrel per day. Over time, the device releases smaller amounts of the hormone, so Mirena needs to be replaced after five years.

Mirena works to prevent pregnancy in several ways:

  • thickening the mucus of the cervix, which helps prevent sperm from entering the cervix
  • preventing sperm from surviving in the uterus
  • stopping the release of an egg from your ovary
  • thinning the lining of your uterus, which makes it harder for a fertilized egg to implant in the uterus (and also reduces your menstrual bleeding)

Mirena must be inserted by a healthcare provider. This should be done within seven days of the start of one of your monthly periods. Your doctor will need to check your device four to six weeks after it’s placed, and once per year after that.

Some health insurance plans are required by law to cover the cost of prescription birth control. The costs of your appointments with your doctor to place or remove Mirena may also be covered.

Check with your insurance provider to see if they cover Mirena. If you don’t have health insurance, you may still be able to get Mirena at no cost through the ARCH Patient Assistance Program.

Mirena is 99% effective in preventing pregnancy. This means it’s more effective than most other forms of birth control, including condoms, the pill, or the hormonal patch, ring, or injection. When used to help reduce heavy menstrual bleeding, Mirena has been shown to be 90% effective after six months. It can decrease your bleeding by more than half.

Like all drugs, Mirena may cause some side effects. Some of these side effects may go away as your body gets used to the medication. Less serious side effects of Mirena can include:

  • pain, bleeding, or dizziness during and after placement
  • changes in menstrual bleeding patterns, such as heavier periods when you first start Mirena, bleeding between periods, or missed periods
  • increased pain and cramps during your period
  • headache or migraine
  • acne
  • tiredness
  • breast tenderness
  • nausea
  • inflammation of your vagina that can cause pain and vaginal discharge
  • enlarged ovaries
  • cysts on your ovaries
  • hair loss
  • expulsion (the device coming out of your vagina on its own)
  • decreased sexual desire
  • unwanted hair growth

Serious side effects

Mirena may cause some serious side effects. Call your doctor right away if you have any of these problems. If you think you’re having a medical emergency, call 911 or go to the nearest emergency room. Serious side effects can include:

Embedment and perforation of the uterus are also serious issues you could face while using Mirena. Embedment means the device attaches to the wall of the uterus. Perforation occurs if the device punctures the uterine wall. If either occurs, the device may need to be surgically removed. Symptoms include pain in your abdomen and vaginal bleeding. You may also experience fever and chills with perforation of the uterus.

Mirena can interact with certain drugs. An interaction can cause one or both medications to work less well. In some cases, it could cause dangerous effects. Be sure to tell your doctor if you take any drugs that could interact with Mirena, such as:

  • blood thinners such as warfarin
  • barbiturates such as phenobarbital and pentobarbital
  • steroids such as prednisone, prednisolone, and methylprednisolone
  • antiseizure drugs such as carbamazepine, oxcarbazepine, topiramate, and phenytoin
  • certain HIV medications such as ritonavir, atazanavir, and efavirenz
  • bosentan
  • rifampin
  • felbamate
  • griseofulvin
  • herbal products, especially St. John’s wort, glucosamine, and ginkgo

Mirena can cause problems in people who have certain health conditions or a history of them. These include a high infection risk, history of pelvic inflammatory disease or pelvic infection, and past or current cancer of the breast, cervix, or uterus. Be sure to discuss your complete health history with your doctor before you use Mirena. Your doctor will determine if Mirena is a safe birth control method for you.

Mirena is a pregnancy category X drug. This means that you should not use it during pregnancy. If you have Mirena and think you’ve become pregnant, call your doctor right away.

Using Mirena during pregnancy can cause an ectopic pregnancy. This is when the pregnancy occurs outside of the uterus, typically in a fallopian tube. Symptoms of an ectopic pregnancy can include unusual vaginal bleeding or pain in your abdomen. Ectopic pregnancy is a medical emergency that typically requires surgery.

In most cases, you can use Mirena while breastfeeding if it’s been more than six weeks since you had your baby. Do not use Mirena before that time. There is a small chance that Mirena could reduce the amount of milk your body makes. If you notice any changes in your milk production while you use Mirena, call your doctor.

Pros of Mirena

  • Mirena is over 99% effective at preventing pregnancy.
  • Mirena reduces the amount of bleeding from your period.
  • Mirena can be used for up to five years and can be replaced after that.
  • Your ability to get pregnant returns almost immediately after Mirena is removed.

Cons of Mirena

  • Mirena releases the hormone levonorgestrel into your body, which can cause mild or serious side effects.
  • Your doctor has to insert Mirena into your uterus — you can’t do it yourself.
  • Mirena may come out of your body on its own.
  • Mirena can be expensive if it’s not covered by your insurance or if you don’t qualify for assistance programs.

The kind of birth control you use is a personal decision. There are many different types available today, including Mirena. If you have questions about which one may be right for you, talk to your doctor. They can help you find a method that works well for you. Questions you might want to ask your doctor include:

  • Is Mirena or another IUD a good choice for me?
  • Am I taking any drugs that might interact with Mirena?
  • Do I have any health conditions that might cause problems if I use Mirena?

Learn more: Birth control options »