New Study Links Depo-Provera to Doubled Brain Tumor Risk as Pfizer Faces Over 1,200 Lawsuits
Key Insights
A new study published in JAMA Neurology found that women using Depo-Provera had a twofold higher risk of developing meningioma (search) brain tumors compared to women not on hormonal birth control.
The research analyzed over 61 million female patient records and found the greatest risk in women who started DMPA after age 31 or used it for four or more years.
Pfizer now faces over 1,200 federal lawsuits from women alleging the company failed to warn about meningioma (search) risks, despite studies dating back to 1983 linking progesterone to brain tumors.
A new study examining over 61 million female patient records has found that women using Depo-Provera face a twofold higher risk of developing meningioma (search) brain tumors compared to women not on hormonal birth control. The research, published in JAMA Neurology by investigators from the Cleveland Clinic and Case Western Reserve University, adds to mounting evidence linking the popular contraceptive injection to serious neurological complications.
The study found that women who used depot medroxyprogesterone acetate (DMPA) - the active ingredient in Depo-Provera - had the greatest meningioma (search) risk when they started the medication after age 31 or used it for four or more years. "In this study, women receiving [DMPA] had a greater relative risk of subsequent meningioma diagnosis, especially with prolonged exposures and starting the medication at older ages," the study authors wrote.
Growing Legal Challenge for Pfizer
The findings come as Pfizer faces over 1,200 federal lawsuits related to Depo-Provera, with women alleging that the pharmaceutical giant failed to warn them about the meningioma (search) risk. The litigation has grown substantially, with the number of cases increasing from 400 to over 550 between May and July 2025, according to court filings.
One Louisiana plaintiff, Robin Phillip, developed an intracranial meningioma (search) that caused her to lose vision in her left eye and struggle to walk. "These women all have meningiomas. Many have surgery, some have radiation, and they've all had their lives greatly impacted," said Ellen Relkin, a lawyer representing Phillip and other plaintiffs.
Phillip's lawsuit claims that studies dating back to 1983 have linked progesterone and meningioma (search), suggesting Pfizer should have studied Depo-Provera risks sooner. The lawsuits allege that Pfizer was aware of the link between the birth control injections and brain tumors but failed to adequately warn of the risk.
Conflicting Evidence and Regulatory Response
The new JAMA Neurology study follows earlier research that found even stronger associations. A study published in June 2025 in Expert Opinion on Drug Safety by Frey et al. found that use of DMPA for more than one year was associated with a 3.5-fold increased risk of developing intracranial meningioma (search) compared to certain combined birth control pills. This followed a French study published in March 2024 in the British Medical Journal that found women who used Depo-Provera for more than one year were 5.6 times more likely to develop an intracranial meningioma.
Mahyar Etminan, one of the authors of the Frey study, said: "Given the elevated risk of meningioma (search) with medroxyprogesterone, women may opt to consider other safer contraceptives."
Despite the accumulating evidence, regulatory responses have been inconsistent globally. Pfizer has acknowledged its awareness of the risks linked to long-term use of the drug and added warning labels in Canada in 2015, and in the UK and Europe in October 2024. On February 25, 2025, Pfizer issued a note to healthcare professionals in South Africa warning that DMPA can cause meningiomas. However, Pfizer has never provided an equivalent warning to women in the United States.
Widespread Use Despite Historical Concerns
Depo-Provera is used by approximately 24.5% of sexually active women in the US at some point in their lifetime, according to a 2023 Centers for Disease Control and Prevention report. Globally, an estimated 74 million women receive Depo-Provera injections according to a 2019 UN study.
The contraceptive has a troubled regulatory history. Originally developed by The Upjohn Company (search) in the 1950s as a cancer treatment, it was marketed as a contraceptive in more than 70 countries from 1969 onwards despite evidence that its active ingredient caused cancer in animals. The FDA denied approval for contraceptive use three times between 1978 and 1992 due to safety concerns before finally approving it in 1992. A "black box" warning was added in 2004 alerting users that it could lead to significant bone mineral density loss with long-term use.
Company Response and Future Implications
Pfizer filed a motion in August to dismiss the litigation, citing its 2023 discovery of a potential link between Depo-Provera and meningioma (search). The company said it had asked the FDA to update the label with a warning, but the agency denied the request because available studies didn't support the warning.
A Pfizer representative stated that "these claims are without merit and will vigorously defend against these allegations." The company added that it "stands behind the safety and efficacy of Depo-Provera, which has been used by millions of women worldwide and remains an important treatment option for women seeking to manage their reproductive health."
Meningioma (search) is typically benign, but the tumors can cause problems by putting pressure on nerves or brain structures. The disease affects women more frequently than men, likely due to the influence of female hormones that can fuel tumor growth. Symptoms associated with these brain tumors include headaches, memory loss, seizures, and speech difficulties, often requiring surgical intervention.