BRIDGEWATER, N.J.— Sanofi announced on Friday that it was recalling the over-the-counter heartburn drug Zantac in the United States and Canada, a month after the Food and Drug Administration first alerted the public that versions of the drug contained low levels of a cancer-causing contaminant.

Several manufacturers of generic versions of Zantac, ranitidine, had already recalled their products, and major chains such as Walgreens, CVS and Walmart had pulled the products from their shelves. Some countries, including Canada, have also requested a halt in distribution of all ranitidine products.

In a statement, Sanofi said it was investigating the issue. “Sanofi is committed to transparency and will continue to communicate results with health authorities from the ongoing testing, and work with them to make informed decisions based on available data and evidence,” the company said.