GSK Shares Drop 10% After Delaware Court Allows Zantac Lawsuits to Proceed

GSK Building_iStock, William Barton

Pictured: GSK's headquarters in London/iStock, William Barton 

Shares of GlaxoSmithKline took a 10% tumble in London trading Monday morning after a Delaware state court ruling determined that scientific evidence would be allowed in the long list of lawsuits related to the discontinued heartburn drug Zantac. 

The ruling allows plaintiffs’ expert witnesses to testify in the cases against the makers of Zantac—first sold as a prescription drug by GSK in the 1980’s before becoming an over-the-counter medicine the next decade. The drugmakers include GSK, Sanofi, Pfizer and Boehringer Ingelheim. 

Sanofi faces around 25,000 cases in Delaware, compared to the approximately 69,000 cases in which GSK is the named defendant, according to Bloomberg.  

Zantac was pulled from the European and U.S. markets in 2019 and 2020 after the FDA requested withdrawal. Investigations at the time showed potential contamination of ranitidine products from N-nitrosodimethylamine (NDMA).  

Commonly found at low levels in water and foods, NMDA is classified by the FDA as a probable carcinogen, which means it “could” cause cancer. The carcinogen levels were extremely low in Zantac, but the FDA found concentrations could increase over time when stored at higher temperatures. 

GSK “disagrees” with the ruling and will “immediately seek an appeal,” the company stated in its press release. The company claims the decision contradicts the federal court’s Multidistrict Litigation (MDL) ruling in December 2022, which dismissed all cases alleging five different cancer types.  

“Scientific consensus is that there is no consistent or reliable evidence that ranitidine increases the risk of any cancer and GSK will continue to vigorously defend itself against all claims,” the British pharma said in a statement. 

The litigation over ranitidine has been plaguing GSK for the last few years. In April 2024, Sanofi agreed to settle 4,000 ranitidine-related cancer lawsuits in U.S. courts. The terms of the deal were not disclosed and the company insists it has no liability in the matter.  

The latest stock drop wiped roughly $8.9 billion from GSK’s market value. The company said in its release that the ruling has no impact on its investment plans for growth. In May 2024, the company announced plans to divest its remaining stake in consumer health spinout Haleon, raising around $1.52 billion for the pharma. 

Kate Goodwin is a freelance life science writer based in Des Moines, Iowa. She can be reached at and on LinkedIn.     

Back to news