Pfizer faces huge lawsuit in US over claims DepoProvera contraceptive injection caused brain tumours

Pharmaceutical giant Pfizer is now embroiled in a major class action lawsuit in the United States, as more than 1,300 women allege they developed brain tumours following use of its Depo-Provera contraceptive injection. The legal action accuses Pfizer of failing to adequately warn both patients and medical professionals about the increased risk associated with prolonged use of Depo-Provera, specifically in relation to a type of benign brain tumour known as intracranial meningioma.

The mounting litigation follows the publication of a British Medical Journal study in March 2024, which linked prolonged use of certain progestogen medications—including medroxyprogesterone acetate, the active ingredient in Depo-Provera—to a 5.6-fold higher risk of meningioma. Meningiomas, while generally benign, can cause significant health issues such as vision and hearing loss, headaches, and seizures, often necessitating surgery that in itself carries further complications.

The number of lawsuits has tripled since May and could eventually reach between 5,000 and 10,000 cases as awareness spreads among American women previously or currently using the injectable birth control. Estimates suggest potential claims against Pfizer could total several billion dollars, underlining both the scale of adopted usage and the seriousness of the associated health concerns.

The key legal battle will take place in Pensacola, Florida, with the court set to rule on whether Pfizer can use a pre-emption defence commonly invoked in pharmaceutical litigation. Pfizer maintains that it attempted to include a brain tumour risk warning on Depo-Provera’s packaging but was prevented from doing so by the US Food and Drug Administration. Plaintiffs counter that Pfizer’s approach to the regulator lacked sufficient specificity, grouping various products together rather than providing targeted data for Depo-Provera alone.

Almost a quarter of sexually active women in the US have used Depo-Provera at some point and its use remains widespread globally. In the United Kingdom, where around 15% of women utilise the drug for contraception and management of conditions such as endometriosis, product labelling was updated last year in response to emerging risk evidence. Pfizer has also modified warning labels in both Canada and across Europe, reflecting growing regulatory scrutiny and consumer demand for safety transparency.

With both shareholder and patient advocacy groups closely monitoring the developments, the case presents a pivotal test for drug manufacturers’ obligations regarding risk communication and the boundaries of regulatory authority. The outcome is likely to have lasting implications for the pharmaceutical industry and for millions of women who rely on hormonal contraceptives worldwide.