Mirena for Endometriosis and Adenomyosis: What to Expect

Mirena is a hormonal IUD that can ease endometriosis pain and the heavy, painful periods of adenomyosis. It sits inside your uterus and releases a small amount of levonorgestrel, a progestin, which thins the lining of the uterus, so periods usually get lighter, and for some people they stop.

If your doctor has offered Mirena, this guide covers what the evidence shows for each condition, what insertion and the first 3 to 6 months are like, the side effects, and what to write down each month. It is general information and not medical advice. Your own doctor decides what is right for you.

For a comparison of all the main treatments, see our guide to endometriosis treatment options. This page is only about Mirena.

What Mirena is and how it works

Mirena is a small, T-shaped plastic device with a reservoir that holds 52 mg of levonorgestrel. It releases about 21 micrograms a day after the first 24 days, and less over the years. A trained healthcare provider puts it in and takes it out.

The hormone acts mainly inside the uterus. It makes the lining thin and inactive. A thin lining bleeds less each month, and less bleeding often means less period pain. Because the effect is local, most people still ovulate while they use it. This is different from tablets such as dienogest, which lower the hormones your body makes.

It is off-label for both conditions. In the US, Mirena is approved for birth control for up to 8 years, and for heavy periods for up to 5 years in people who also want it as birth control. Endometriosis and adenomyosis are not on the label. Doctors can still prescribe it for them, based on guidelines and studies.

Other levonorgestrel IUDs exist. Liletta is the other brand also used for heavy periods, while Kyleena and Skyla are used for birth control only.

Mirena for endometriosis: what the evidence shows

The European endometriosis guideline (ESHRE) recommends a levonorgestrel IUD as one way to reduce endometriosis pain. For teens with severe period pain or endometriosis pain, a progestin given by tablet or by IUD is one of the first-line hormone choices.

After endometrioma (ovarian cyst) surgery, the same guideline advises doctors to consider a 52 mg levonorgestrel IUD or a combined pill for at least 18 to 24 months, to help stop painful periods from coming back.

The trial evidence for the IUD after surgery is small: across 4 trials, Cochrane found not enough evidence to support the IUD after surgery to reduce endometriosis pain. In two small trials, period pain went down more with the IUD than with no treatment, but this result is uncertain because the certainty of the evidence was very low to low.

For endometriosis, the IUD and hormone medicines that act on the whole body showed no clear difference in pain relief in trials that compared them. Irregular bleeding was more common with the IUD (26.8% of people in those trials).

So for endometriosis, Mirena is one reasonable option, not a proven best choice. It can suit you if you also want long-term birth control, or if tablets gave you side effects.

Mirena for adenomyosis: what the evidence shows

In adenomyosis, tissue like the uterine lining grows into the muscle wall of the uterus. It can cause heavy, painful periods and a bigger uterus. Hormonal IUDs such as Mirena are one of the hormone options that can help with heavy and abnormal bleeding.

The evidence is stronger for adenomyosis than for endometriosis, but it is still limited. People with adenomyosis who used the IUD had less period pain overall than people on medicines that act on the whole body, such as birth control pills, at 3, 6 and 12 months, in a 2022 review of randomized trials. The gap grew over time. Their monthly blood loss also went down more at 6 and 12 months. One exception was triptorelin, an injected GnRH agonist, which eased pain more than the IUD at 6 months. Most of the trials enrolled patients in China and had a relatively high risk of bias.

If adenomyosis makes your belly look swollen, see our page on adenomyosis belly.

What insertion is like

A provider puts the IUD in through your cervix during a short clinic visit. During and after insertion, you can have cramping, bleeding, dizziness, sweating, a fast heartbeat or fainting. Your provider may suggest a painkiller before insertion.

If you have a lot of pelvic pain, insertion can hurt more than you expect. Tell your provider before the visit. Ask what pain relief they offer and if you can have the procedure on a day when you can rest afterwards.

The IUD has two thin threads that stay at the top of your vagina. Your provider can show you how to feel for the threads with clean fingers. Call them if you cannot feel the threads, or if you can feel the hard part of the device. The first check-up is usually 4 to 6 weeks after insertion, and then once a year.

The first 3 to 6 months

The first months are often the hardest part. During the first 3 to 6 months, you may have more bleeding and spotting days than before, and the pattern may be irregular. After that, the number of bleeding days usually goes down, but bleeding can stay irregular.

About 20% of users have no periods by one year. This is a known effect of Mirena.

Pain relief can take months, not days. In the adenomyosis trials, the IUD's lead in pain relief over other medicines was small at 3 months and larger at 6 and 12 months. The early spotting and cramps can hide the benefit, so ask your doctor when you should review how it is going. A monthly note makes that review easier.

Common side effects

These rates come from clinical trials in more than 5,000 users. The trials were for birth control and heavy periods, not endometriosis.

Less common side effects include hair loss, extra hair growth, nausea and the IUD coming out. In one study of long-term users, 9% reported weight gain, but it is not known if Mirena caused it.

Ovarian cysts. Because most users still ovulate, about 8% get ovarian cysts. Most cause no symptoms, and most go away on their own in 2 to 3 months. Some cause pelvic pain or pain during sex. If you have endometriosis, tell your doctor about new one-sided pelvic pain, so they can check it.

The IUD can come out. About 4.5% of users had the IUD come out over 5 years. Mirena usually makes bleeding lighter over time, so bleeding that gets heavier again can be a sign that it has moved.

Who may not be able to use Mirena

Mirena must not be used if any of these apply to you:

• You are pregnant or could be pregnant
• Fibroids or another problem changes the shape of the inside of your uterus
• You have a pelvic infection now, or had pelvic inflammatory disease (PID) before, unless you had a pregnancy in the uterus after it
• You have an untreated infection of the cervix or vagina
• You have, or may have, cancer of the uterus or cervix
• You have, or had, breast cancer or another cancer that is sensitive to progestin
• You have bleeding from the uterus with no known cause

Tell your doctor if you have a bleeding disorder or take blood thinners, have migraine with changes in your vision, or have had an ectopic pregnancy. These do not always rule out Mirena, but your doctor needs to know.

What to track each month

A short monthly record answers the main question at your review: is Mirena helping enough to keep it? Each month, write down:

• Bleeding days. Which days you had spotting, and which days you needed a pad or tampon.
• Pain score. Your usual pain and your worst pain from 0 to 10, and what the pain stopped you doing.
• Painkillers. How many days you needed pain relief.
• Pain with sex or bowel movements. These can come from endometriosis outside the uterus, so note them on their own.
• Mood. How many days you felt low or anxious.
• Side effects. Headaches, acne, breast pain, discharge or anything new.
• Threads. If you check them, note the date and if you could feel them.

If you can, write down one or two cycles of your usual symptoms before insertion. It gives you something to compare with. For help with the pain score, see how to describe period pain.

Endolog is a pain and symptom diary for endometriosis and adenomyosis. You log pain, bleeding, other symptoms and notes on the days they happen, so after a few months you have a clear record to show your doctor. A paper notebook works too, or print the free medication log.

When to call your doctor

Get emergency help (911 in the US, 999 in the UK, 000 in Australia) if:

• You have sudden weakness in an arm or leg, a drooping face, trouble speaking, chest pain, or swelling of your lips, tongue or throat. These are serious side effects that need care at once.
• You have severe belly pain with a missed period or new bleeding. Pregnancy with an IUD in place is rare, but about half of these pregnancies are ectopic, which is an emergency.

Call your doctor soon if:

• You get severe pain or a fever soon after insertion.
• You have pelvic pain, fever, chills or unusual discharge. These can be signs of infection.
• You cannot feel the threads, or you can feel the device.
• Your bleeding gets heavy after it had become light, or you have had periods and then have none for 6 weeks.
• Your skin or eyes turn yellow.
• Your mood gets low, or depression comes back.

Talk to your doctor at your review if:

• Your pain has not improved.
• The bleeding pattern or side effects still make daily life hard.

Do not try to take the IUD out yourself. Your provider can remove it at any time if it does not suit you.

Frequently asked questions

Is Mirena approved for endometriosis?

No. In the US, Mirena is approved for birth control and heavy periods. Doctors use it off-label for endometriosis and adenomyosis, and the European guideline recommends it for endometriosis pain.

How long does Mirena take to help endometriosis or adenomyosis?

It can take months. Bleeding and spotting are often irregular for the first 3 to 6 months. In adenomyosis trials, the IUD's lead in pain relief over other medicines grew from 3 to 12 months.

Will Mirena stop my periods?

It can. About 20% of users have no periods after one year. Most others have lighter bleeding, which can stay irregular.

Does Mirena cure endometriosis or adenomyosis?

No. It can ease symptoms while it is in place. Symptoms can come back after it is removed. Adenomyosis symptoms often go away after menopause.

Will Mirena affect my fertility later?

In studies, about 80% of people who wanted to get pregnant did so within 12 months after removal. Endometriosis and adenomyosis can affect fertility on their own, so talk to your doctor if you plan a pregnancy.

Is Mirena better than dienogest for endometriosis?

There is no clear winner. In endometriosis trials, pain relief was similar with the IUD and with hormone medicines that act on the whole body, and the side effects differ. See our dienogest guide to compare.

This article is for general information. It does not replace advice from your own doctor, who decides what treatment is right for you. If you think you have an emergency, call 911 in the US, 999 in the UK or 000 in Australia.