The maker of the popular heartburn drug Zantac has stopped worldwide distribution of the drug - both branded and generic forms.
The Sandoz division of Novartis says the halt is precautionary, while it investigates a potentially cancer-causing chemical found in both versions.
On Friday, the FDA issued a warning about low levels of the probable carcinogenic chemical NDMA, but said it's not clear if it poses a risk to patients.
Ranitidine is the generic name for Zantac.
The FDA says the amount of NDMA found in heartburn drugs is about the same as that found in common foods.
U.S health officials say people can continue taking Zantac and other heartburn medications with ranitidine, but prescription patients should consult their doctor if they want to switch.
NDMA is the same chemical linked to dozens of recalls of prescription blood pressure drugs in the past year, including a commonly prescribed one called valsartan.
The recalled drugs, which were manufactured in China, had unacceptably high levels of NDMA.
Zantac maker pulls drug over concerns of cancer-causing chemical