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How does Mirena affect periods?

Understanding your periods and Mirena coil | Mirena coil and periods: 0-6 months after the fitting | Mirena coil and periods: 6 months or more after the fitting | Periods with Mirena coil: frequently asked questions (FAQs)

Mirena is a small T-shaped device known as an intrauterine system (IUS) that is fitted into your womb by a trained healthcare professional.

Mirena may be prescribed by your doctor as a treatment for heavy menstrual bleeding (heavy periods). It can also be prescribed as a contraceptive and as part of a hormone replacement therapy (HRT) treatment plan.

Understanding your periods and the Mirena coil

Mirena may change your period patterns.

What happens during a period?

A period is the part of the menstrual cycle when a woman bleeds from her vagina for between 2 and 7 days. Bleeding during your period happens when the lining of your womb is shed every month.

Most girls get their first period around age 12, but it can start as early as age 8. The first 2 days of a period may be heavy for most women, with the blood being red in colour. On lighter bleeding days, the blood could be pink or brown. For most women, periods happen around every 28 days, but it can range between every 21 to 35 days.

Women who are approaching menopause may experience periods that are further apart.

Mirena as a contraceptive and its effect on periods

Mirena works by releasing a small amount of hormone called levonorgestrel into the womb. As a contraceptive, Mirena prevents pregnancy by thinning the lining of the womb and thickening the cervical mucus, preventing sperm from entering and fertilising the egg. Mirena may also prevent ovulation in some women.

Women using Mirena as a contraceptive usually have periods less often or may have no period at all.

Studies show that after 1 year of using Mirena as a contraceptive, 57% of women have periods less often and 16% have no periods. After 8 years, 26% have periods less often and 34% have no periods.

If your periods on the Mirena coil have stopped and then suddenly return, you should speak to your doctor immediately to check if everything is okay.

Mirena as a treatment for heavy periods

Mirena works for up to 8 years to control heavy periods, however, you should let your doctor know if your symptoms return after 5 years of using Mirena.

Studies show that in women with heavy periods, blood loss decreases by 62 to 94% at the end of three months and by 71 to 95% at the end of six months of using Mirena.

You might have lighter, painful periods, irregular bleeding or spotting during the first few months after Mirena is fitted. If you do not have lighter periods after 3-6 months, speak to your doctor and they might prescribe another treatment.

Mirena periods and the menopause

Mirena can be used as part of an HRT plan. When it is used in this combination with an oestrogen, some women may experience spotting or irregular bleeding during the first few months. Studies show that this usually becomes lighter over the first year and that 30 to 60% of users experience no periods.

If you are experiencing any changes to bleeding patterns after:

using Mirena for some time
3 months after any changes to the oestrogen component of your HRT

You should speak to your doctor at the earliest.

This could be a sign that Mirena has been expelled, is not working well enough for you, or there are changes to your womb.

Mirena coil and periods: 0-6 months after the fitting

Changes to your period, such as irregular bleeding, can happen in the first few months after the Mirena fitting. You may experience pain and light cramps after it has been fitted. If you experience ongoing pain and bleeding, you should speak with your doctor immediately to check that everything is okay.

Mirena and spotting

Light bleeding, known as spotting, is a possible side effect within the first few months of getting Mirena fitted.

Mirena and irregular periods

In the first 2-3 months after the fitting, you may experience irregular periods with Mirena. You may notice bleeding more often, bleeding that lasts longer, or heavier bleeding. Heavy bleeding and spotting should slowly settle within a few months after Mirena is fitted.

Mirena coil and periods: 6 months or more after the fitting

After having Mirena for a while, the amount of bleeding and how often you bleed will become less. Studies show that in fertile women, the average number of days with spotting gradually reduces from 9 to 4 days during the first 6 months of use.

You should speak to your doctor immediately if you experience any:

severe pain and continuous bleeding
new vaginal bleeding
irregular or heavy bleeding that continues for longer than 6 months
a change in your usual bleeding pattern after using Mirena for longer than 6 months.

Periods with Mirena coil: frequently asked questions (FAQs)

Is it normal to bleed after I’ve had Mirena fitted?

You may experience light bleeding after the Mirena fitting. If you experience continuous abnormal bleeding and severe pain after the fitting, you should see your doctor immediately to make sure everything is okay.

Can I get the Mirena coil fitting on my period?

Yes. The ideal time to have Mirena fitted is within 7 days of the start of your period. If it is fitted during this time, it will protect you from pregnancy straight away. If it is fitted at another time in your menstrual cycle, it may not protect you against pregnancy immediately. In this case, you should use condoms or avoid vaginal sex for 7 days after it is fitted.

How long does it take for Mirena to stop periods?

You should have lighter periods with Mirena after 3 to 6 months. You are likely to have lighter bleeding each month, and over time, you may stop having periods altogether.

If you are using Mirena to help with heavy menstrual bleeding but your periods have not become lighter after 3 to 6 months, you should speak to your doctor about different treatments that will better suit you.

Does the Mirena coil stop periods?

In clinical studies, 17% of fertile women reported that they did not have their period for at least 3 months during their first use of Mirena. By year 8 of Mirena use, this number increased to 34%.

Studies also show that extended bleeding (bleeding for more than 8 days during a period) decreases from 20% to 3% during the first three months of use.

Is missing my periods with Mirena coil unhealthy?

Missing periods with the Mirena coil is normal, as some women may get no periods on Mirena.

Will my period return to normal if Mirena is removed?

Some NHS clinics say that periods may return within a month after Mirena is removed. If you are going through perimenopause, your periods may naturally change in flow and frequency – this can be masked while on Mirena. If you have any concerns about changes to your period or abnormal bleeding after Mirena removal, speak to your doctor.

If I miss periods with the Mirena coil, am I pregnant?

It is very rare for women to get pregnant while on Mirena. The possibility of pregnancy is 2 in 1000 women in the first year of using Mirena.

Missing periods with the Mirena coil may not mean that you are pregnant. Some women may not get periods at all while on Mirena. If you have not had a period for more than 6 weeks, you can do a pregnancy test to check if you are pregnant. If the test is negative, you don’t need to do another test unless you have other symptoms of pregnancy such as sickness, tiredness or breast tenderness. If the test is positive, you should see a doctor as soon as possible to discuss the benefits and risks of Mirena removal.

Which sanitary products should I use with Mirena?

The use of sanitary pads is recommended, however, if you use tampons and menstrual cups, you should change them with care to avoid pulling the strings of Mirena. Your doctor or nurse might recommend that tampons should not be used immediately and only be used 4 weeks post-insertion to avoid dislodging of threads.

Some women find that because their periods are so much lighter after the first few months that panty liners provide enough protection.

Is the Mirena coil causing a build-up of period blood in my body?

Period blood is not being stored in your body. The decrease in the amount of blood shed during your period is caused by the hormone levonorgestrel in Mirena. The hormone thins the lining of the womb, which could cause a lighter period with Mirena coil.

Can I have spotting and irregular periods with Mirena if I am going through menopause?

Yes, irregular bleeding or spotting can happen in perimenopausal women during the first few months of using Mirena.

If you are using Mirena together with oestrogen as a part of hormone replacement therapy (HRT), spotting or unscheduled vaginal bleeding can happen in the first 6 months of starting HRT.

It can also happen in the first 3 months after any changes to the dose or type of the oestrogen you are taking. Make sure to read the patient information leaflet for your oestrogen for more information as well.

Talk to your doctor immediately if you are experiencing any bleeding beyond these timeframes.

Does Mirena coil stop ovulation?

The hormone in Mirena, levonorgestrel, could stop the release of eggs (ovulation) in some women. In most women, ovulation usually remains normal.

Will I have period pain with Mirena coil?

Mirena treats heavy menstrual bleeding. However, Mirena is not a treatment for period pain. If you experience severe pain or lower belly pain while a Mirena is fitted, you should speak to your doctor.

Glossary

Coil: A common name for an IUS or an IUD. It is a small device placed inside the womb to prevent pregnancy.

Hormone replacement therapy (HRT): Treatment that replaces the hormones that the body makes less of during menopause, including oestrogen to relieve menopause symptoms and progesterone to protect the lining of the womb.

Intrauterine system (IUS): A small T-shaped device placed inside the womb that slowly releases a hormone.

Levonorgestrel: One of the hormones that performs the function of a progestogen.

Menopause: Menopause is a condition caused by a fall in hormone levels in women between the ages of 45 or 55, but it can happen earlier.

Oestrogen: A hormone that is naturally made by the body. Oestrogen, along with progesterone is essential to puberty, the menstrual cycle, pregnancy, and menopause.

Perimenopause: The time in a woman’s life when her periods become irregular before menopause.

Abbreviations

HRT, hormone replacement therapy; IUS, intrauterine system; NHS, National Health Service.

PP-MIR-GB-0324 | October 2026

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