Walmart has become the latest store to halt sales of the popular heartburn treatment Zantac after health regulators warned about a potentially dangerous contaminant in the drug.

The nation’s largest retailer said today that it suspended sales of all drugs sold over the counter, or without a prescription, that include Zantac’s active ingredient, ranitidine. Aside from Zantac, that includes Equate and Member’s Mark brands.

The U.S. Food and Drug Administration said last month it detected low levels of a probable cancer-causing chemical in Zantac and related generic drugs to treat ulcers and reflux disease. The same chemical has been linked to dozens of recalls of prescription blood pressure drugs in the past year.

The drugstore chains CVS Health , Walgreens and Rite Aid have already pulled Zantac products from their shelves.