Is the Mirena IUD a Good Option for Emergency Birth Control?

Most people have used some form of birth control during their lives. But condoms can break and pills might be skipped by mistake. Whatever the reason, if you’ve had unprotected sex and are concerned about getting pregnant, there are a few methods available to help.

These methods are known as emergency contraception (EC). EC can prevent a pregnancy from happening, but it won’t stop a pregnancy that’s already started.

Recently, an intrauterine device (IUD) called Mirena (levonorgestrel), has gained notice as a possible option for EC. In addition to providing immediate EC, Mirena also continues to provide protection from pregnancy for years after insertion. 

Below, we’ll talk about currently available EC choices and whether Mirena might be a possible option for EC.

What emergency contraception (EC) options are currently available?

The FDA has approved two pill forms of EC: ella (ulipristal) and Plan B (levonorgestrel). ella works best if used within 5 days of unprotected sex. Plan B is most effective if used within 3 days of unprotected sex. While these pill options may be convenient, they don't provide long-term pregnancy prevention.

A third form of EC available is ParaGard, also known as the copper IUD. ParaGard is not FDA approved for EC. But sometimes healthcare providers recommend it off-label as EC because it’s very effective. ParaGard can be used within 5 days of unprotected sex to provide EC.

After insertion, ParaGard continues to provide protection against pregnancy for up to 10 years. But because this option can cause heavy periods for some people, you may wonder if there are any other EC options.

This is where Mirena might be an option.

What is Mirena and how does it work?

Mirena is an IUD that releases a progestin (a lab-made form of progesterone), called levonorgestrel, slowly over time. It’s placed inside the uterus by a healthcare provider at their office. The insertion procedure usually takes about 30 minutes. Once in place, Mirena can prevent pregnancy for up to 7 years.

Mirena is thought to prevent pregnancy by causing the following three changes:

• Mirena thickens your cervical mucus (the fluid made by your cervix). This makes it harder for sperm to enter your uterus.

• Mirena slows or stops the movement of sperm. This makes it more difficult for sperm to swim if they enter the uterus.

• Mirena thins the lining of the uterus. This means that even if sperm do reach and fertilize an egg, it would be less likely to implant and start a pregnancy.

What are the benefits of Mirena?

There are a number of benefits when it comes to using Mirena birth control, including:

• It is very discreet. You wouldn’t be able to tell if a person has a Mirena IUD in place.

• It is over 99% effective at preventing pregnancy. That means that less than 1 in every 100 people gets pregnant while using it.

• It works to prevent pregnancy for up to 7 years. But you can remove it earlier than that if you change your mind.

• It is low maintenance. Once inserted, it’ll keep working for years without you having to do anything. This can be helpful if you have trouble remembering to take pills.

• It is considered a “quick start” method of birth control. This means you can get started with it at any point during your menstrual cycle.

• It tends to cause lighter periods for most women who use it. In fact, about 20% of those using Mirena stop getting periods altogether after using it for a year.

Can you use the Mirena IUD for EC?

Like ParaGard, Mirena is not FDA approved for EC in the case of unprotected sex. But recently, Mirena has gained favor as an option for EC. A recent study suggests that Mirena works just as well as ParaGard for EC.

In the past, it was recommended to also take oral EC (like Plan B) if Mirena was placed shortly after unprotected sex. This new data suggests Mirena may be an effective option for EC without the addition of other medications.

Which is better for EC: Mirena or ParaGard?

This decision comes down to what you and your healthcare provider decide is best for you. Both Mirena and ParaGard appear to be effective when used for EC. 

They’re both considered off-label for EC, which means they’re being used in a way that hasn’t been approved by the FDA. But ParaGard is currently a recommended option for EC by several health expert groups.

In the Mirena study discussed above, over 700 people were given either Mirena or ParaGard for EC. During the study, there was one pregnancy in the Mirena group and no pregnancies in the ParaGard group. Researchers interpreted these results to mean that Mirena is just as effective as ParaGard for EC.

Since these results are newer, they have yet to be included in current EC recommendations. But your healthcare provider may determine that Mirena is a good EC option for you.

What are the downsides and who shouldn’t use Mirena?

Unlike the EC options you take by mouth, Mirena must be placed by a healthcare provider at their office. This provider must also be trained to place Mirena. Getting to a provider who’s able to insert Mirena may be difficult for some people. And if it has been close to 5 days since having unprotected sex, you may not be able to wait for an appointment. In these cases, an oral EC option may be a better choice for you. 

Mirena isn’t the right choice for everyone. If you’re already pregnant, you can’t have this device inserted. Mirena isn’t an appropriate option if you’re looking to stop a pregnancy. Check out our article on Plan C (medication abortion) for more information on what to do if you’re pregnant and don’t want to be.

Mirena also shouldn’t be used if you have:

• A medical condition that affects the size or shape of your uterus (e.g., uterine fibroids) 

• Current or past breast cancer

• Cervical or endometrial cancer

• Current pelvic inflammatory disease (a serious infection of the pelvis)

• A history of a pelvic infection following an abortion or after giving birth

• Sexually transmitted infections (STIs) that haven’t been treated yet, such as chlamydia

• Unexplained vaginal bleeding

These are not the only reasons you may not be able to use Mirena. Make sure your healthcare provider is aware of all medical conditions and allergies you have.

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Written by:

Nicole E. Cieri-Hutcherson, PharmD, BCPS, NCMP

Nicole E. Cieri-Hutcherson, PharmD, BCPS, NCMP, has over a decade of experience as a pharmacist, professor, and researcher. She was a full-time clinical professor in the pharmacy practice department at D’Youville School of Pharmacy before subsequently joining the faculty of the pharmacy practice department at the University at Buffalo School of Pharmacy and Pharmaceutical Sciences.

Edited by:

Christina Aungst, PharmD

Christina Aungst, PharmD, is a pharmacy editor for GoodRx. She began writing for GoodRx Health in 2019, transitioning from freelance writer to editor in 2021.

Reviewed by:

Alyssa Billingsley, PharmD

Alyssa Billingsley, PharmD, is the director of pharmacy content for GoodRx. She has over a decade of experience as a pharmacist and has worked in clinical, academic, and administrative roles.

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