The hormonal IUD (or IUS for intrauterine system) is an extremely effective contraceptive! You might know these by their brand names, like Mirena, Kyleena, or Skyla.

While we use it for that purpose very often and it has gained popularity in the last decade, there's a lot of other things that the IUD can help with, especially in perimenopause.

The hormonal IUD (or IUS) can be a lifesaver for heavy flow and period pain.

Plus, it actually can offer endometrial protection if you're someone using estrogen as part of your menopause hormone therapy (MHT).

I'll get to that in a minute. First, let's talk IUD.

How does the hormonal IUD work?

The hormonal IUD is a small, T-shaped device inserted into your uterus by a healthcare provider. Unlike copper IUDs, which contain copper wiring, the hormonal IUD features a reservoir containing a progestin (a molecule that's kind of like our hormone, progesterone) called levonorgestrel. This hormone is released slowly into the uterus over its lifespan.

Levonorgestrel works locally in three ways (the first bullet point is the main way):

• Thins out the uterine lining: Making it tough for an egg to implant and dramatically reducing menstrual flow.
• Thickens cervical mucus: Creating a barrier that prevents sperm from traveling toward an egg.
• Interferes with fertilization: Creating an inhospitable environment just in case sperm do manage to slip through.

Different IUDs deliver different doses. The higher-dose option (like Mirena) contains 52mg of levonorgestrel. It starts off releasing around 18–20mcg per day, gradually tapering down toward ~10mcg per day near the end of its lifespan. Lower-dose options like Kyleena or Skyla release less hormone and need replacing sooner (around the 3–5 year mark).

What are the benefits of a hormonal IUD during perimenopause?

Perimenopause, on average, lasts 4-8 years. It is defined by hormonal fluctuations and menstrual cycle changes like heavy flow, prolonged flow, shorter cycles, longer cycles, irregular cycles. For some people, it can be really disruptive, while not so much for others. The hormonal IUD can offer a few advantages for someone in perimenopause:

• Contraception you don't have to think about. It provides highly effective, multi-year birth control during a stage of life where ovulation is unpredictable and erratic BUT pregnancy is still possible.
• Addresses heavy menstrual bleeding. Because levonorgestrel thins the uterine lining, many users experience significantly lighter periods, spotting-only type of periods, and some people lose their bleeds entirely.
• Relief from period pain. It can decrease menstrual cramps. For some people, it's suppressing a menstrual cycle so other cyclical symptoms might go away too.
• You likely continue to ovulate. While some users may (temporarily) stop ovulating, most people continue their natural ovulatory cycles while using a hormonal IUD.
• Localized hormone exposure. The vast majority of the hormone stays concentrated in your uterus rather than circulating throughout your entire body at high levels.

Why is a hormonal IUD or progesterone used with estrogen in Menopause Hormone Therapy (MHT)?

If you decide to start estrogen therapy for perimenopause or menopause symptoms (like hot flashes or night sweats) or for osteoporosis prevention, you need a way to protect your uterus. If you don't have a uterus, we don't need to protect it, obviously, and you can use estrogen on its own (although you might be prescribed a progesterone for other signs and symptoms!).

Taking estrogen on its own (known as unopposed estrogen) is associated with a significant, dose-dependent risk of endometrial hyperplasia (an overgrowth of the uterine lining) which can lead to endometrial cancer (or uterine cancer) within 1 to 3 years of exposure.

To prevent this risk, menstruators and women with a uterus using systemic estrogen require a progesterone or progestin to protect the endometrium. This is typically given sequentially (for ~2 weeks per month) OR continuously (daily). The best protection comes from daily or continuous dosing, especially if we're using hormone therapy for more than 5 years.

Long-term sequential HRT use (over 5 years) can still carry a small, dose-dependent risk of endometrial hyperplasia due to periodic progestogen gaps.

There are multiple options for the progesterone or progestin component. BUT where the 52mg levonorgestrel IUD like Mirena shines in perimenopause is when/if:

• you have heavy bleeding, and/or
• you have period pain, and/or
• have a condition like adenomyosis (which can lead to irregular bleeding and/or pain), and/or
• need contraception, and/or
• need endometrial protection because you're starting up on estrogen for menopause hormone therapy

Delivering progestin directly to the endometrial lining provides strong, continuous local protection against estrogen-induced overgrowth. Note: the lower-dose IUDs are not used for this purpose.

How do I know when I’m in menopause if I have a hormonal IUD and no periods?

Because the hormonal IUD often causes light spotting or causes your period to disappear altogether (amenorrhea), we can’t really rely on the classic definition of menopause (which is 12 consecutive months without a period).

To figure out whether you’ve reached menopause while using an IUD or not, we look at the full picture:

• Your age: The average age of menopause is 51 in Canada.
• Your signs and symptoms: Tracking hot flashes, mood fluctuations, sleep disruptions, vaginal dryness, and other changes that come with the menopause transition.
• Running FSH (follicle stimulating hormone) in your blood, sometimes a few tests over a period of time. FSH starts to go up as we approach our final period ever and stays elevated postmenopause.

What are the side effects and potential risks of a hormonal IUD?

While the hormonal IUD is generally safe and well-tolerated, there are a few important considerations to keep in mind:

• Systemic side effects: Even though the hormone is mostly localized, a tiny amount of levonorgestrel enters your bloodstream. Some people are more sensitive to this than others, experiencing side effects like bloating, mild mood shifts, breast tenderness, or weight changes.
• No STI protection: IUDs do not protect against sexually transmitted infections.
• Rare structural complications: There is an extremely small risk of the device shifting, expelling, or causing uterine perforation during insertion.
• Ectopic pregnancy risk: While pregnancy on an IUD is extremely rare, if conception does occur, there is a higher likelihood of it being an ectopic pregnancy compared to pregnancy without an IUD.
• Insertion can be painful: There are many reports of menstruators having difficulties receiving pain management and/or proper instructions about the insertion and removal of their IUD. Make sure to have a full discussion with your medical provider.

As always, nothing in this post is medical advice, so always talk to your health team as you're making sure if this is the right fit for you and what to expect.

How long can I keep my hormonal IUD for contraception vs. endometrial protection?

It is important to distinguish between how long an IUD lasts for birth control versus how long it lasts for endometrial protection in MHT:

• For Contraception: Higher-dose 52mg IUDs (like Mirena) are approved in many regions for up to 8 years of effective birth control.
• For Endometrial Protection (MHT): Current clinical evidence and guidelines support using the 52mg levonorgestrel IUD for up to 5 years to protect the uterine lining when taking estrogen therapy.

If you are using your IUD both as birth control and as the progestin portion of your MHT regimen, plan to discuss replacing it at the 5-year mark to ensure your uterine lining remains fully protected. Or, if menopause has been reached, a different type of protection like progesterone or progestin can be used.

Is the Mirena IUD right for me?

I obviously can't give you the answer here as this is not a medical appointment, but it CAN be a good option for a lot of people. There's obviously downsides, but lots of upsides too!

It's far more than just a contraceptive. In perimenopause, it serves a dual (or even triple!) purpose: keeping heavy bleeding and painful cramps under control, preventing unplanned pregnancy, and providing effective endometrial protection if you choose to start estrogen therapy.

As a Naturopathic Doctor & Menopause Society Certified Practitioner, this is something I talk about with many of my patients. If you're in Ontario and looking for guidance, I see patients across Ontario virtually + in-person in Newmarket and Innisfil. You can book an appointment here.

References Voedisch, A. J. (2025). Menopause, 33(1), PMID: 40957020 Government of Canada: Medical Management of Menopause Symptoms.