Pfizer is facing a growing legal firestorm as new research links its popular birth control shot, Depo-Provera, to a dramatically increased risk of brain tumors. Now, hundreds of women are taking the pharmaceutical giant to court—alleging they were never warned about the dangers hidden in each dose.

According to a press statement released on behalf of the 400 plaintiffs, Pfizer and other manufacturers were aware of the link between the progestin-based contraceptive shot and meningioma, a serious brain tumor—but chose not to warn American women. While warning labels were added in Canada, the UK, Europe, and South Africa, no such action was taken in the U.S., despite growing evidence and mounting global concern.

The suit follows a study published by the British Medical Journal last year that found that people who took the progestin-based shot for a year or more were up to 5.6 times more likely to develop meningioma, a brain tumor that forms, per the Cleveland Clinic, on the meninges, or layers of tissue that covers the brain and spinal cord.

Futurism reports: Though Pfizer attached warning labels about meningioma to Depo-Provera sold in Canada in 2015 and the UK, Europe, and South Africa after the 2024 study was published, no such label was deployed in the United States — a failure which according to the lawsuit is “inconsistent [with] global safety standards.”

In an interview with the website DrugWatch, one of the suit’s plaintiffs, who was identified by the initials TC, said that she had been “told how great Depo-Provera was” and decided to start it after an unplanned pregnancy that occurred when she’d taken the since-discontinued birth control pill Ortho Tri-Cyclen Lo.

“I thought it would be more reliable and convenient since I wouldn’t have to take it daily,” TC told the site, referencing the four annual injections Depo-Provera requires. “I had no idea it would lead to such serious health problems.”

After being on the contraceptive shot for three years — and experiencing intense headaches, months-long uterine bleeding, and weight gain — the woman finally consulted her doctor and was diagnosed with meningioma. She’s since been undergoing treatment and experienced some relief, but even that experience has been “physically and emotionally draining” because she has to get regular MRIs to monitor the tumor, which likely isn’t fatal but still greatly affects her quality of life.

“It’s a constant worry that the tumor might grow,” TC said, “and the appointments feel never-ending.”

That fear was echoed by others who spoke to the Daily Mail about their meningioma diagnoses after taking Depo-Provera. Unlike TC, Andrea Faulks of Alabama hadn’t been on the shots for years when she learned of her brain tumors, which caused her years of anguish.

Faulks told the British website that she’d begun taking the medication back in 1993, the year after it was approved by the FDA in the United States. She stopped taking it only a few years later, but spent decades having splitting headaches and experiencing dizziness and tremors. After being dismissed by no fewer than six doctors, the woman finally got an MRI last summer and learned that she had a brain tumor — and is now undergoing radiation to shrink it after all this time.

“I know this is something I’m going to have to live with for the rest of my life, as long as I live,” Faulks told the Daily Mail.

Currently, the class action case against Pfizer on behalf of women like Faulks and TC is in its earliest stages as attorneys representing those hundreds of women with brain tumors start working to make them whole.

Even if they receive adequate payouts, however, that money won’t take away their suffering, or give them back the years of their life lost to tumors they should have been warned about.