Cancer concerns have led the makers of Zantac to recall the popular heartburn drug.

Testing by the U.S. Food and Drug Administration found contamination in samples of the drug with a potentially cancer causing substance called NDMA.

They, along with European regulators were tipped off by an online pharmacy.

The drug’s French maker is recalling the medication.

Users of the drug are being advised to either contact their doctor about possible alternative medications they could take.