The Swiss drugmaker's steps follow an investigation by U.S. and European regulators into the presence of the impurity, N-nitrosodimethylamine (NDMA), in the drug, ranitidine, and a distribution halt in Canada announced late Tuesday.
Health Canada said it had requested makers of the drug to stop distribution as it gathers more information and consults with international health regulators.
Branded versions of the drug such as Sanofi Zantac are available for over-the-counter sale in Canada, while generic versions are available for sale both OTC and with prescription.
A distribution halt is different from a recall and means that existing stock of the drugs in pharmacies or stores can still be sold.
Neither the U.S. Food and Drug Administration nor the European Medicines Agency had asked patients to stop taking the drug when the regulators said last week they were reviewing the safety of ranitidine.
Novartis said in an emailed statement its step was precautionary and adequate measures "will be implemented in alignment with relevant health authorities as required."
(Reporting by Manas Mishra in Bengaluru and Michael Erman in New York; Editing by Maju Samuel)