The Mirena migration lawsuit refers to a wave of litigation brought by thousands of women against Bayer Healthcare after their Mirena intrauterine devices moved from the uterus, perforated the uterine wall, and in some cases traveled into the abdominal cavity where they damaged surrounding organs. Approximately 2,700 women sued Bayer over Mirena adverse events, with over 2,000 migration and perforation cases consolidated into federal multidistrict litigation. In early 2018, Bayer offered $12.2 million to settle approximately 4,800 uterine perforation and migration claims, with individual payouts ranging from $2,500 to $50,000 depending on the severity of injury. That litigation is now effectively over, with the MDL officially closed in April 2021 and most law firms no longer accepting new migration cases. But migration was not the only problem linked to Mirena.
A separate MDL involving nearly 1,800 lawsuits alleged the device caused pseudotumor cerebri, a dangerous buildup of pressure around the brain. Those cases were dismissed in 2020 after a judge excluded the plaintiffs’ expert witnesses. More recently, a breast cancer class action filed in March 2022 alleges Bayer failed to disclose that Mirena increases breast cancer risk by approximately 20 to 30 percent. That case remains active and is the only significant Mirena-related litigation still proceeding as of early 2026. This article covers the full history of the migration lawsuits, what happened with settlements, how the pseudotumor cerebri cases collapsed, and what the breast cancer litigation means for women who currently use or previously used Mirena.
Table of Contents
- What Exactly Happened in the Mirena Migration Lawsuits?
- How the Migration MDL Was Resolved and Why Settlements Were Small
- The Pseudotumor Cerebri Cases and Their Collapse
- The Breast Cancer Class Action and What Makes It Different
- Why Most Attorneys Are No Longer Taking Mirena Migration Cases
- FDA Adverse Event Data and What It Reveals
- What Comes Next for Mirena Litigation
- Conclusion
- Frequently Asked Questions
What Exactly Happened in the Mirena Migration Lawsuits?
mirena is a levonorgestrel-releasing IUD that has been FDA-approved since 2000. It is one of the most widely used long-acting reversible contraceptives in the world. Migration occurs when the device shifts from its intended position inside the uterus, sometimes partially and sometimes completely. In the worst cases, the device perforates the uterine wall and moves into the abdominal cavity, where it can puncture the bladder, kidneys, intestines, fallopian tubes, ovaries, or cervix. Women who experienced these complications often required surgical intervention to locate and remove the device, and some suffered lasting organ damage or infections. The lawsuits alleged that Bayer knew about the risk of migration and perforation but failed to adequately warn patients and doctors. Plaintiffs pointed to a stark discrepancy between what clinical trials showed and what was happening in the real world.
In clinical trials, the perforation rate was reported at less than 0.1 percent. But postmarketing studies told a different story, with perforation rates of 6.3 per 1,000 insertions among breastfeeding women and 1.0 per 1,000 among non-breastfeeding women. That gap between controlled trial data and real-world outcomes became a central issue in the litigation. The risk was found to be highest when insertion occurred within six weeks postpartum, a detail that plaintiffs argued should have been communicated far more aggressively. Over 45,000 adverse event reports about Mirena have been filed with the FDA since the device’s approval. By July 2020, the FDA Adverse Event Reporting System included 104,000 reports concerning Mirena. Those numbers reflect a wide range of complaints, not all related to migration, but they paint a picture of a device whose real-world performance generated significant concern among users and regulators alike.
How the Migration MDL Was Resolved and Why Settlements Were Small
The migration and perforation cases were consolidated into a federal multidistrict litigation to streamline pretrial proceedings. The goal of an MDL is to handle common discovery issues efficiently before cases are either settled or sent back to their original courts for trial. In this case, the MDL did not go well for plaintiffs. The migration MDL cases were dismissed in 2016, and that dismissal was affirmed by the Second Circuit Court of Appeals in 2017. A second round of cases was dismissed in 2019. The MDL was officially closed in April 2021. The $12.2 million settlement Bayer offered in early 2018 to resolve approximately 4,800 claims works out to modest individual payments.
Average payouts ranged from $2,500 to $50,000, with the amount depending on injury severity. For a woman who underwent emergency surgery to remove a migrated device from her abdomen and suffered lasting complications, $50,000 is not a large sum. For context, a single laparoscopic surgery to retrieve a migrated IUD can cost tens of thousands of dollars before accounting for lost wages, follow-up care, or pain and suffering. However, if a plaintiff’s injuries were relatively minor, such as a device that shifted but was caught early and removed without complications, even $2,500 may have represented a practical resolution given the cost and uncertainty of continued litigation. The key limitation for plaintiffs was the legal question of whether Bayer’s warnings were adequate under existing FDA labeling standards. Courts generally found that the warnings provided with Mirena did reference the risk of perforation, even if plaintiffs argued those warnings were insufficient or buried in fine print. This made it difficult to prove a failure-to-warn claim, which was the primary legal theory in most cases.
The Pseudotumor Cerebri Cases and Their Collapse
Separate from the migration litigation, nearly 1,800 women filed lawsuits alleging that Mirena caused pseudotumor cerebri, also known as idiopathic intracranial hypertension. This condition involves elevated pressure of the cerebrospinal fluid around the brain and can cause severe headaches, vision problems, and in serious cases, permanent vision loss. The plaintiffs in MDL 2767 argued that the levonorgestrel hormone released by Mirena contributed to this dangerous condition. The outcome was devastating for the plaintiffs. The presiding judge excluded the plaintiffs’ expert witnesses after finding insufficient scientific evidence to support a causal link between Mirena and pseudotumor cerebri. Without expert testimony establishing causation, the cases could not survive summary judgment.
All pseudotumor cerebri cases were dismissed on June 11, 2020, and the final Mirena MDL closed on December 8, 2020. This is a concrete example of how mass tort litigation can fail entirely at the expert evidence stage. Under the Daubert standard used in federal courts, judges serve as gatekeepers for scientific testimony, and if the science does not meet that threshold, even thousands of plaintiffs with real medical conditions cannot proceed to trial. The dismissal does not necessarily mean Mirena cannot cause intracranial hypertension in any individual. It means the available scientific evidence at the time of litigation was not strong enough to meet the legal standard for admissibility. That distinction matters because science evolves, but for the women in MDL 2767, the legal window closed.
The Breast Cancer Class Action and What Makes It Different
The only active Mirena-related litigation of significance is a class action lawsuit filed in March 2022 in the Northern District of California. The case, Priya Sidhu v. Bayer, alleges that Bayer failed to disclose that Mirena increases the risk of breast cancer by approximately 20 to 30 percent. Unlike the migration and pseudotumor cerebri cases, this lawsuit has survived early legal challenges. A federal judge rejected Bayer’s motion to dismiss, allowing the case to proceed. What makes this litigation potentially stronger than the earlier Mirena cases is the emerging scientific support. An October 2024 nationwide Danish study examined the link between levonorgestrel-releasing IUDs and breast cancer risk in women aged 15 to 49.
Large-scale population studies from countries with comprehensive health registries, like Denmark, carry significant weight in litigation because they track millions of patients over extended periods. If the study’s findings support the plaintiffs’ claims, it could substantially strengthen their position. However, no settlements have been awarded in the breast cancer litigation as of late 2025, and Bayer has historically fought Mirena claims aggressively through trial rather than settling early. The tradeoff for potential plaintiffs in this case is time versus outcome. Joining a class action means lower individual legal costs but also less control over the process and potentially smaller individual recoveries if a settlement is reached. Women with strong individual claims, particularly those diagnosed with breast cancer while using Mirena for extended periods, may need to weigh whether individual litigation would produce a better result. But with the class action already past the motion to dismiss stage, the vehicle for pursuing these claims exists.
Why Most Attorneys Are No Longer Taking Mirena Migration Cases
As of 2024 and 2025, most law firms have stopped accepting new Mirena migration cases. This is not because migration no longer occurs. It is because the legal avenues for pursuing these claims have been exhausted. The MDL is closed, the settlements have been distributed, and the appellate courts have upheld the dismissals. For an attorney evaluating whether to take a new case, the combination of unfavorable precedent and the cost of litigation makes new migration claims economically unviable. There is an important warning here for women who are currently experiencing or have recently experienced Mirena migration. The closure of the MDL does not mean you have no legal options, but it does mean the path is significantly narrower.
Individual state court claims may still be possible depending on your jurisdiction’s statute of limitations and the specific facts of your case. However, finding an attorney willing to take such a case on contingency will be difficult. If you believe you have a claim, you should consult with a medical device attorney promptly rather than assuming the litigation is entirely dead. Statutes of limitations vary by state and by the type of claim, and delay can permanently bar an otherwise valid case. The broader limitation is that the legal system moved faster than many potential plaintiffs expected. Women who experienced migration complications years after the MDL closed may find themselves with no recourse, even if their injuries are severe. This is a recurring pattern in mass tort litigation where consolidation and resolution happen on a timeline that does not always align with when injuries manifest.
FDA Adverse Event Data and What It Reveals
The sheer volume of adverse event reports associated with Mirena is notable. Over 45,000 reports were filed between its 2000 approval and the early years of litigation, and by July 2020, the total in the FDA Adverse Event Reporting System had reached 104,000. These reports cover the full spectrum of complaints, from minor side effects to life-threatening complications. It is important to understand that FAERS data does not establish causation.
A report means someone experienced an adverse event while using the device, not that the device necessarily caused it. But when the numbers reach six figures for a single product, they signal a pattern that warrants serious scrutiny. The discrepancy between clinical trial perforation rates of less than 0.1 percent and postmarketing rates of 6.3 per 1,000 for breastfeeding women is a telling example of how clinical trial conditions can underrepresent real-world risks. Clinical trials control for patient selection, insertion technique, and follow-up in ways that everyday clinical practice does not. Breastfeeding women, in particular, face elevated risk because the postpartum uterus is softer and more susceptible to perforation, especially within the first six weeks after delivery.
What Comes Next for Mirena Litigation
The future of Mirena litigation rests almost entirely on the breast cancer class action. If the Sidhu v. Bayer case produces favorable rulings or a significant settlement, it could open the door to additional claims from women who used Mirena and were subsequently diagnosed with breast cancer. The October 2024 Danish study and any future research into hormonal IUDs and cancer risk will be pivotal in shaping both the legal and regulatory landscape.
Beyond the courtroom, the Mirena litigation has already had practical effects. Bayer has updated its labeling over the years to include more detailed warnings about perforation risk, particularly for postpartum and breastfeeding women. Whether those label changes go far enough remains a point of debate. For women currently considering or using Mirena, the litigation history serves as a reminder to have candid conversations with their healthcare providers about individual risk factors, especially regarding the timing of insertion relative to childbirth and any personal or family history of breast cancer.
Conclusion
The Mirena migration lawsuit represents a mass tort that produced limited financial recovery for most plaintiffs. Bayer’s $12.2 million settlement for approximately 4,800 perforation and migration claims translated to individual payouts between $2,500 and $50,000, amounts that many injured women found inadequate given the severity of their complications. The pseudotumor cerebri cases fared even worse, with all claims dismissed after expert testimony was excluded. Both MDLs are closed, and the migration and perforation chapter of Mirena litigation is finished.
The breast cancer class action filed in 2022 is the remaining thread. With emerging scientific evidence from large-scale studies and a federal judge allowing the case to proceed past the motion to dismiss stage, this litigation has a plausible path forward that the earlier cases lacked. Women who used Mirena and were diagnosed with breast cancer should consult with an attorney experienced in pharmaceutical litigation to evaluate their options. For everyone else, the Mirena story is a case study in how medical device litigation can span decades, produce mixed results, and evolve in directions no one initially anticipated.
Frequently Asked Questions
Is the Mirena migration lawsuit still active?
No. The migration and perforation MDL was officially closed in April 2021. Most law firms stopped accepting new Mirena migration cases by 2024 to 2025. The only active Mirena-related litigation is the breast cancer class action filed in 2022.
How much did Mirena migration lawsuit settlements pay?
Bayer offered $12.2 million in early 2018 to settle approximately 4,800 uterine perforation and migration claims. Individual payouts ranged from $2,500 to $50,000 depending on injury severity.
What is the Mirena breast cancer lawsuit about?
Filed in March 2022 as Priya Sidhu v. Bayer in the Northern District of California, the class action alleges Bayer failed to disclose that Mirena increases breast cancer risk by approximately 20 to 30 percent. A federal judge rejected Bayer’s motion to dismiss, and the case is proceeding. No settlements have been awarded as of late 2025.
How common is Mirena perforation?
Clinical trials reported perforation rates below 0.1 percent. Postmarketing studies found higher rates of 6.3 per 1,000 insertions for breastfeeding women and 1.0 per 1,000 for non-breastfeeding women. The risk is highest when insertion occurs within six weeks after giving birth.
Can I still file a Mirena migration lawsuit?
It is unlikely. The MDL is closed, settlements have been distributed, and appellate courts upheld the dismissals. Individual state court claims may be possible depending on your jurisdiction and statute of limitations, but finding an attorney willing to take a new migration case will be difficult.
How many adverse event reports have been filed about Mirena?
Over 45,000 adverse event reports were filed with the FDA since Mirena’s 2000 approval. By July 2020, the FDA Adverse Event Reporting System included 104,000 reports concerning Mirena, covering a wide range of complaints beyond just migration.