GlaxoSmithKline on Tuesday said it is recalling the popular heartburn medicine Zantac in all markets as a "precaution," days after the U.S. Food and Drug Administration found "unacceptable" levels of probable cancer-causing impurity in the drug.

Zantac, also sold generically as ranitidine, is the latest drug in which cancer-causing impurities have been found. Regulators have been recalling some blood pressure and heart failure medicines since last year.

Britain's medicines watchdog said GlaxoSmithKline (GSK) was recalling four prescription-only Zantac medicines: a syrup, an injection and tablets of 150 and 300 milligram (mg) dosages. (bit.ly/2IATooO)