Three of the nation’s largest pharmacies will stop selling the heartburn 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.

CVS Health Corp.

CVS, +1.59%

  suspended sales of Zantac and products containing ranitidine on Saturday. “This action is being taken out of an abundance of caution,” the company said in a statement. On Monday, Walgreens

WBA, +1.65%

  and Rite Aid Corp.

RAD, -4.53%

  said they, too, were removing the drugs from their shelves.

Earlier this month, the FDA said some ranitidine medicines, including Zantac, “contain a nitrosamine impurity called N-nitrosodimethylamine (NDMA) at low levels. NDMA is classified as a probable human carcinogen.”

The FDA said it is still investigating whether the NDMA levels pose a risk to patients. “Although NDMA may cause harm in large amounts, the levels the FDA is finding in ranitidine from preliminary tests barely exceed amounts you might expect to find in common foods,” the agency said in a statement.

The FDA said it was not recalling the medication nor calling for patients to stop using products with ranitidine, but said that those with concerns should talk to their doctor or consider similar over-the-counter medications that do not contain ranitidine.

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

Zantac is made by Sanofi SA

SNY, +0.15%

 .

Read More