Zantac was the world's bestselling heartburn drug — then it turned out to cause cancer

Zantac (ranitidine) was one of the best-selling drugs in pharmaceutical history, generating billions in annual revenue across multiple manufacturers. In June 2019, online pharmacy Valisure filed a citizen petition with the FDA revealing that ranitidine products contained dangerously high levels of N-nitrosodimethylamine (NDMA), a probable human carcinogen. The contamination was not caused by a manufacturing error — it was intrinsic to the ranitidine molecule itself, which degrades into NDMA over time and more rapidly at elevated temperatures.

The FDA confirmed the finding in September 2019, and by April 2020 ordered all ranitidine products withdrawn from the US market. The European Commission suspended ranitidine across the EU. The revelation that a molecule approved in 1977 and taken by millions daily had an undiscovered carcinogenic degradation pathway triggered thousands of product liability lawsuits against manufacturers including GSK, Pfizer, Sanofi, and Boehringer Ingelheim.

A 2023 Bloomberg investigation reported that the manufacturer had been aware of cancer risks for decades and had kept them quiet. The litigation costs mounted into the billions, though many cases were consolidated in multi-district litigation. A reformulated, stable version of ranitidine was eventually re-approved in Australia and the US, but the original formulation had caused incalculable damage to both patients and the reputations of the world's largest drug companies.