Heavy menstrual bleeding, also known as menorrhagia, is a common condition that has a significant impact on quality of life. About 1 in 20 women ages 30-49 will consult a doctor about heavy menstrual bleeding each year.

The Mirena intrauterine system (IUS) is a hormone-releasing IUD. In addition to providing long-acting reversible contraception, the Mirena is also an effective treatment for heavy periods. 

Here, we’ll go over everything you need to know to understand how the Mirena can be used to treat heavy menstrual bleeding, and whether it might be a good option for you. 

What is menorrhagia or heavy menstrual bleeding?

Menorrhagia is the medical term for heavy menstrual bleeding or heavy periods. 

The Society of Obstetricians and Gynecologists of Canada defines heavy menstrual bleeding as any of the following:

• Bleeding that lasts over 7 days
• Bleeding that soaks through at least one pad or tampon per hour for several hours
• Needing to change sanitary products at night
• Blood clots that are the size of a quarter or larger 

Heavy menstrual bleeding can have a significant impact on a person’s quality of life. The good news is that it is often treatable, and there are many different treatment options including NSAIDs, oral contraceptives, hormonal IUDs, as well as other drugs and surgical options.

What is the Mirena IUS?

Mirena is a hormone-releasing IUD, also known as an intrauterine system (IUS). The Mirena consists of a T-shaped device which releases a hormone called levonorgestrel, a synthetic form of progesterone.

Mirena is one of the most effective forms of contraception available. The Mirena is over 99% effective at preventing pregnancy, and in Canada it is approved for use up to 5 years when placed in women under age 25, and up to 7 years for women 25 and older. 

How does Mirena treat heavy menstrual bleeding?

Mirena is approved by Health Canada to treat idiopathic menorrhagia, or heavy menstrual bleeding of unknown cause. 

In women with heavy menstrual bleeding, the lining of the uterus may be thicker, causing longer and heavier periods which can lead to iron loss and iron deficiency anemia . Levonorgestrel, the active ingredient in the Mirena, works to thin the lining of the uterus. It also reduces how much the lining thickens during each menstrual cycle.

Mirena tends to have an effect right away, but the benefits increase the longer the IUS stays in place. Over time, women may experience less and less bleeding with each cycle, and 80% of women stop having periods entirely. 

The Mirena would not be a good treatment option for someone planning to become pregnant soon, or someone who is not open to hormone-containing treatment.

What do studies say?

Studies show that the Mirena is an effective treatment for heavy menstrual bleeding. According to a 2021 review, treatment with Mirena causes a “rapid, significant, and clinically meaningful reduction in menstrual blood loss over time.” It also improves iron levels, which can be low in women with heavy periods, and is an effective alternative to surgical treatments. 

A 2015 clinical trial looked at the Mirena IUS in 70 women with menorrhagia between 30-55 years old. The study followed the women over 3 years. The study found an 80% decrease in menstrual blood loss 4 months after insertion of the Mirena, a 95% decrease in blood loss after 1 year, and a 100% decrease after 2 years, meaning the womens’ periods stopped. 

A 2009 meta analysis found that Mirena was as effective as endometrial ablation, a surgical procedure, at reducing blood loss. Mirena had fewer side effects, and it does not affect a woman’s future fertility. 

A 2004 clinical trial looked at 236 women experiencing menorrhagia. The average age of the participants was 43. Participants were randomly assigned to receive either the Mirena IUS or a hysterectomy. The study found that the two groups experienced similar levels of health related quality of life and psychosocial well-being at 5 years.

What about other types of IUDs?

There are three types of IUDs available in Canada:

• The copper IUD (contains no hormones)
• The Mirena IUD
• The Kyleena IUD

Kyleena is a hormone-releasing IUD which contains less of the active ingredient than Mirena. Kyleena may reduce heavy bleeding, but it is not clinically indicated for this purpose. A healthcare provider can help you decide between different hormone-releasing IUD options. 

Copper IUDs contain no hormones, however, they can increase menstrual bleeding and are not recommended for the treatment of heavy menstrual bleeding.

Summary

The Mirena IUS is an effective treatment for heavy menstrual bleeding. It may be a good option for women who are also interested in long-acting contraception, and who are open to progesterone only treatment . Compared with surgical treatments, the Mirena is reversible and preserves fertility. If you are experiencing heavy periods and are considering treatment, the Mirena may be a good option. Talking to a healthcare provider may help you decide whether Mirena is right for you.