Mirena, a widely used levonorgestrel-releasing intrauterine system (IUS), has been a popular choice for contraception and management of heavy menstrual bleeding for many years. Concerns have emerged regarding a potential link between Mirena and an increased risk of breast cancer. These concerns have led to legal actions against its manufacturer, seeking to address alleged failures in warning users about such risks. This article explores these lawsuits, outlining the claims made and the current landscape of the litigation.
Understanding Mirena and Breast Cancer Concerns
Mirena is a small, T-shaped device inserted into the uterus that continuously releases a synthetic progestin hormone called levonorgestrel. This hormone primarily prevents pregnancy by thickening cervical mucus, inhibiting sperm movement, and thinning the uterine lining. It also effectively treats heavy menstrual bleeding by similarly affecting the uterine lining.
Allegations of an increased risk of breast cancer in Mirena users stem from the hormonal nature of the device. Some studies have suggested a link between progestin-only contraceptives, including levonorgestrel-releasing IUDs, and a slightly elevated risk of breast cancer. For instance, a 2024 Danish study involving nearly 78,595 women found that those using levonorgestrel-releasing IUDs had a 40% higher chance of developing breast cancer, translating to about 14 additional cases per 10,000 women over five years. Other research indicates a 20-30% excess risk compared to non-users of hormonal contraceptives.
The current Mirena label acknowledges that individuals with a history or suspicion of breast cancer should not use hormonal contraception, including Mirena, because some breast cancers are hormone-sensitive. However, it also notes that observational studies on the breast cancer risk with levonorgestrel-releasing IUS do not offer conclusive evidence of increased risk, suggesting more research is necessary. Despite this, if enough progestin is absorbed into the bloodstream, it can cause changes in breast tissue, potentially leading to cancer development over an extended period.
The Legal Claims Against Mirena’s Manufacturer
Plaintiffs are pursuing legal action against Bayer, the manufacturer of Mirena, primarily alleging that the company failed to adequately warn both users and medical professionals about the device’s potential breast cancer risk. These lawsuits commonly claim that Bayer either knew or should have known about this increased risk but neglected to provide sufficient warnings. Allegations include misrepresenting Mirena’s risks as “uncommon” and hiding harmful side effects from women and their doctors.
Many lawsuits contend that Mirena had unreasonably dangerous design defects and was not reasonably safe for its intended use, exposing users to risks that outweighed its benefits. Plaintiffs also accuse Bayer of deceptive marketing practices that promoted Mirena as safe and convenient, particularly targeting mothers. These claims assert that the manufacturer failed to update product warnings or notify the FDA about studies showing an increased risk of breast cancer among users.
These legal actions seek compensation for medical expenses, lost wages, and pain and suffering experienced by those who allege harm from Mirena.
Who Can File a Mirena Breast Cancer Lawsuit?
Individuals considering legal action related to Mirena and breast cancer generally need to meet specific criteria. A primary requirement is having used a Mirena IUD. Additionally, claimants typically must have received a breast cancer diagnosis, often specifically invasive breast cancer, after the Mirena device was inserted.
The timeline between Mirena use and breast cancer diagnosis is also an important factor. Legal claims often investigate whether the diagnosis occurred within a reasonable period following Mirena insertion or removal. Medical records play a significant role in these cases, serving as evidence of Mirena use, the breast cancer diagnosis, and the progression of the condition.
A statute of limitations, which is a legal deadline for filing a lawsuit, applies to these claims. This time limit varies by state, but typically requires legal action to be initiated within a few years of discovering the injury or realizing its potential connection to Mirena. Consulting with a legal professional is advisable to understand the specific requirements and deadlines applicable to an individual’s situation, as these are general guidelines and not definitive legal advice.
Current Status of Mirena Breast Cancer Litigation
The landscape of Mirena litigation has seen various developments over time. Historically, thousands of Mirena lawsuits were filed against Bayer concerning side effects such as uterine perforation and pseudotumor cerebri. While some of these earlier cases saw settlements, many others were dismissed due to challenges in establishing causation through expert testimony.
Regarding breast cancer claims specifically, a class action lawsuit alleging Mirena causes breast cancer was filed in California in March 2022. This lawsuit claims Bayer failed to warn users about an increased risk of breast cancer. In October 2023, a federal judge allowed this class action to proceed, rejecting Bayer’s motion to dismiss, indicating that many of Bayer’s arguments were science-based questions for later in the pretrial process.
Despite this, previous Mirena litigation, including some breast cancer claims, has faced difficulties, with judges sometimes ruling that expert witnesses could not provide adequate scientific evidence linking Mirena to certain injuries. As of September 2025, while some class action lawsuits related to breast cancer risk continue to move forward, earlier large-scale multidistrict litigations (MDLs) concerning other Mirena-related injuries have largely closed. The progression of current breast cancer-related cases will likely depend on scientific evidence and expert testimony regarding the causal link between Mirena and breast cancer.