Key takeaways

• Kyleena® and Mirena® are both hormonal IUDs that provide over 99% effective birth control with long-lasting, low-maintenance protection.
• Mirena® contains a higher dose of hormone and is FDA-approved to treat heavy periods, making it a good option if you’re looking for period relief.
• Kyleena® delivers a lower hormone dose and is slightly smaller in size, which may be more comfortable if you haven’t given birth or are sensitive to hormones.
• Mirena® lasts up to 8 years, while Kyleena® offers protection for up to 5 years.
• Side effects like lighter periods or spotting are common and usually temporary as your body adjusts.
• Neither option affects future fertility. Most people can start trying to conceive as soon as the device is removed.
• While Nurx doesn’t provide IUDs, our medical team can help you explore other birth control options that match your needs and lifestyle.

Kyleena vs. Mirena IUDs for birth control

Looking into long-acting birth control and torn between Kyleena® and Mirena®? These two hormonal intrauterine devices (IUDs) are both safe, highly effective, and low-maintenance options that offer years of protection. But while they have a lot in common, there are also a few key differences that can help you decide which one better fits your body and lifestyle.

Kyleena® delivers a lower dose of hormones, which may be a better fit if you’re sensitive to hormonal changes. Mirena® contains a slightly higher dose of progestin and is also FDA-approved to treat heavy periods—a bonus if that’s something you’re dealing with.

Here are the details of both IUDs so you can feel informed, empowered, and supported in making the right choice for your reproductive health.

What are hormonal intrauterine devices?

If you’re exploring low-maintenance, long-term birth control, hormonal IUDs like Kyleena® and Mirena® are highly effective options to consider. They’re small, flexible, T-shaped devices that are placed in your uterus by a healthcare provider, where they steadily release a small amount of progestin to prevent pregnancy. No daily routine required.

Hormonal IUDs are more than 99% effective, making them one of the most reliable forms of birth control available. Once in place, they provide years of protection with no need to track pills, schedule refills, or worry about timing. That ease and consistency are part of why so many people find them appealing.

Because the hormone is released directly into the uterus, many people experience fewer systemic side effects compared to other hormonal methods like the pill. For some, this means fewer mood changes or hormone-related symptoms.

While Nurx doesn’t prescribe or place IUDs, we believe everyone deserves accessible, expert guidance to make informed choices about their reproductive health. If you’re curious about hormonal IUDs (or want to explore other options), we’re here to help you find the method that feels right for you.

How Kyleena® and Mirena® prevent pregnancy

Here’s how these hormonal IUDs work to prevent pregnancy.

Thickens cervical mucus to block sperm

The hormone released by these IUDs (levonorgestrel, a form of progestin) causes your cervical mucus to thicken. That mucus acts like a natural barrier, making it difficult for sperm to pass through the cervix and reach an egg. You can think of it as turning water into honey: sperm simply can’t swim through it very easily.

Slows down sperm movement

Levonorgestrel also affects sperm directly, reducing their ability to move. That means fewer sperm can reach the egg, even if they make it past the cervical barrier.

Thins the uterine lining

Another layer of protection comes from changes to your uterine lining (endometrium). With less buildup each cycle, the lining is less receptive to a fertilized egg, making implantation unlikely.

Triggers a localized inflammatory response

The presence of the IUD itself creates a gentle inflammatory response in your uterus. It’s nothing to be alarmed about. This response actually makes your uterus an unfriendly environment for sperm, decreasing their chances of survival.

What are the key differences?

Both Kyleena® and Mirena® are highly effective IUDs that provide long-term birth control, and while they work in similar ways, a few important differences (like hormone levels, size, and FDA-approved uses) can help guide your decision.

Hormone levels and period relief

Both Kyleena® and Mirena® are highly effective, long-acting birth control options.

Mirena® contains a higher dose of hormone (levonorgestrel), which can make it a better choice if you have heavy periods; it’s also FDA-approved for that purpose.

Kyleena® has a slightly lower hormone dose, which some people prefer for fewer hormonal side effects.

Size and comfort

Kyleena® is smaller than Mirena®, which may make insertion easier, especially if you haven’t given birth or have a smaller uterus. It’s designed to be effective and comfortable across more body types.

How long do they last

Kyleena® works for up to 5 years.

Mirena® protects for up to 8.

If you want longer-lasting coverage, Mirena® may be the better fit.

Choosing what’s right for you

Both IUDs are safe, reliable, and over 99% effective.

If you’re leaning toward fewer hormones or a smaller device, Kyleena® might be the one.

If you’re hoping to ease heavy periods or want longer protection, Mirena® may be a better match.

How they might affect your menstrual bleeding patterns

One of the biggest changes people notice after getting a hormonal IUD like Mirena® or Kyleena® is how it affects their periods. These IUDs can significantly reduce bleeding, but exactly how your body responds may vary. Knowing what to expect can make the transition feel a little easier.

Lighter periods (or none at all)

Many people find that their periods get much lighter within a few months of getting a hormonal IUD. What used to require super tampons might eventually only need a panty liner, or no protection at all.

This shift usually happens in stages. At first, your flow may lighten but stay about the same length. Over time, periods often become both shorter and lighter. With Mirena®, some people stop having periods entirely, often after about one year.

This is one of the reasons many choose Mirena® or Kyleena®, not just for birth control, but to help manage heavy or painful periods. These IUDs are among the most effective and well-reviewed long-acting methods available today.

Irregular bleeding

During the first few months, it’s normal to experience irregular bleeding or spotting. You might notice bleeding between periods, longer periods, or flow that starts and stops unexpectedly. It can be frustrating, especially if you were hoping for instant improvement, but it’s usually temporary.

What’s happening? Your body is adjusting to the steady hormones from the IUD. These hormones thin the uterine lining, which leads to lighter bleeding, but it takes time for that change to become consistent.

Most people find that bleeding becomes more predictable and manageable after a few months. Keeping track of your cycle can help you notice changes over time and gives your provider helpful insights if questions come up.

Are they both effective?

When it comes to preventing pregnancy, both Kyleena® and Mirena® are highly effective options. With failure rates extremely low, they’re among the most reliable forms of contraception available (even more effective than the pill, patch, or ring), and they don’t require daily upkeep.

Why IUDs work so well

The real advantage of hormonal IUDs like Kyleena® and Mirena® is their “set it and forget it” convenience. Once placed by a healthcare provider, they offer continuous protection without any action needed on your part. 

That’s a big deal, especially since most birth control failures happen due to missed pills or incorrect use. With an IUD, you don’t have to remember anything; you’re covered 24/7.

What about future fertility?

It’s common to wonder how long it takes to get pregnant after an IUD removal. The good news: fertility typically returns right away. As soon as the IUD is removed, you can begin trying to conceive; there’s no delay or need to wait for hormones to leave your system.

Studies show that previous use of a hormonal IUD doesn’t negatively affect your ability to get pregnant. Many people go on to conceive within a few months after removal.

And if you’re nervous about the removal process, know that it’s usually quick and only mildly uncomfortable—often easier than the insertion! Your provider gently removes the device by pulling on its strings, and that’s it.

How to choose between Kyleena® and Mirena®

Deciding between Kyleena® and Mirena® depends on what works best for you. Both are highly effective, low-maintenance IUDs, but your choice may come down to personal preferences and health needs.

Think about what matters most: Do you want lighter periods? Minimal hormones? Long-term protection? There’s no one-size-fits-all answer, just the option that best fits your life right now. And the good news? Both offer over 99% protection against pregnancy.

When to consider a new IUD

If you’re switching from another birth control method, your provider can usually time IUD insertion to maintain seamless pregnancy protection. For first-time users, inserting the IUD during your period may make the process more comfortable. Your cervix is slightly more open, and the timing provides added reassurance that you’re not already pregnant.

You might also consider switching IUDs if your needs have changed. Maybe you’ve had Kyleena® and now want Mirena® for its longer-lasting protection. Or perhaps you’re dealing with heavier periods and want something that can help manage them. Whatever the reason, it’s okay to reevaluate what works for you.

Talk to a healthcare provider

Your provider is your best partner in this decision. They’ll talk through your health history, listen to your priorities, and help you weigh the pros and cons. Be open about past experiences with birth control, mental health concerns, or side effects that feel like deal-breakers—those details help guide the most supportive recommendation.

While Nurx doesn’t offer IUDs, we do offer trusted birth control options through online care. Our medical team can help you explore your choices, answer questions, and make the process simple and supportive, so you feel informed and confident in whatever you choose next.

Making the choice that works for you

Kyleena® vs Mirena®? It all comes down to what matters most to you. Both IUDs are highly effective at preventing pregnancy and offer long-term, low-maintenance protection.

Kyleena® is a great fit for those who prefer lower hormone levels or need a smaller device. Mirena® may be the better choice if you’re looking for longer-lasting protection or help managing heavy periods. It’s FDA-approved for that, in addition to contraception.

Understanding the key differences, and how they align with your lifestyle and goals, can help you have a more productive conversation with your healthcare provider.

Even though Nurx doesn’t offer IUDs, we’re here to support your reproductive health journey. Whether you’re exploring long-acting options or looking for daily, weekly, or monthly methods, our licensed providers can help you find birth control that fits your life—on your schedule.

Explore your birth control options with Nurx.

Frequently Asked Questions (FAQ)

What is better, Mirena® or Kyleena®?

It depends on your personal needs. Kyleena® may be a better fit if you haven’t had children or are sensitive to hormones. Mirena® releases a higher dose of hormone and is often preferred for managing heavy menstrual bleeding. Your provider can help you decide what’s best for you.

What is the downside of Kyleena®?

Some people experience headaches, cramping, or changes in their periods after getting Kyleena®. Serious side effects are rare, but they can include infection or uterine issues. Most people find that side effects improve with time.

Does Mirena® help with acne?

It’s possible, but it could have a negative effect, too. Mirena® contains progestin, which can increase oil production in the skin. If you’ve been using birth control that contains estrogen—like the pill—you might notice changes in your skin when switching. If acne is a concern, talk to your provider about your options.

How big is Kyleena® compared to Mirena®?

Kyleena® is slightly smaller (28mm x 30mm) than Mirena® (32mm x 32mm). That size difference may matter if you’ve had discomfort with IUD insertion in the past or have a smaller uterus. The smaller size doesn’t change how well it works.

The information provided is not a substitute for professional medical advice, diagnosis, or treatment. You should not rely upon this content for medical advice. If you have any questions or concerns, please talk to a medical professional.