Walgreens Boots Alliance Inc. (NASDAQ:WBA) and Rite Aid Corp. (NYSE:RAD) have both joined rival CVS Health Corp. (NYSE:CVS) in discontinuing sales of the popular Zantac heartburn drug and generic products with the same active ingredient, ranitidine in them from their pharmacies.

The move means three of the nation’s largest pharmacy chains will stop selling the medication Zantac and similar generic products following a warning by the Food and Drug Administration that the drug may contain low levels of a potentially cancer-causing substance.

READ: CVS Health to discontinue sales of popular Zantac heartburn treatment and its own generic products with the same active ingredient

Earlier this month the FDA said some of the pills contained small amounts N-nitrosodimethylamine (NDMA),  a known carcinogen, which has also been found in some widely used blood pressure medicines.

All three drug-store companies said customers could return their ranitidine medications for a refund.

CVS said Monday that the move to suspend over-the-counter sales of the heartburn drug was taken out of caution and noted that Zantac brand products and brand ranitidine products have not been recalled, and the FDA is not currently recommending that patients stop taking ranitidine.

Zantac is currently made by French multinational pharmaceutical company Sanofi SA. GlaxoSmithKline PLC (LON:GSK) – the drug’s original makers  – was earlier this week also reported to have stopped distributing its generic version and had recalled its products from India and Hong Kong.

Last week Sandoz, a unit of Swiss drugs giant Novartis said it was halting distribution of Zantac in all its markets, including the United States and Canada, following safety review of the drug by US and European drug regulators.

Contact the author at jon.hopkins@proactiveinvestors.com