(CNN)Drugmaker Sanofi is voluntarily recalling of the heartburn medication Zantac OTC.
The recall impacts drugs sold in the United States and Canada. Sanofi is working with the US Food and Drug Administration to determine the extent of the recall.
Tests of Zantac and other ranitidine medications found N-nitrosodimethylamine, or NDMA, an impurity that is considered a possible carcinogen by the US Environmental Protection Agency, the FDA and Health Canada said in September. NDMA can be unintentionally introduced into manufacturing through certain chemical reactions.
The FDA has been testing several drugs after it found the impurity in blood pressure and heart failure medicines known as ARBs.