UK doctors are being told to stop prescribing four types of a heartburn medication called Zantac or ranitidine as a "precautionary measure".
It follows concern in several countries that products may contain an impurity that has been linked to cancer.
The four being recalled are Zantac 150mg/10ml Syrup, Zantac 50mg/2ml Injection, Zantac 150mg Tablets and Zantac 300mg Tablets.
But patients should keep taking their prescribed medicine, officials advise.
The Medicines and Healthcare products Regulatory Agency (MHRA) says the health risk of discontinuing the medicine is higher than the potential risk presented by the contaminant N-nitrosodimethylamine (NDMA).
Anyone who is concerned about taking their medication should speak to their doctor or pharmacist.