Heartburn drugs taken by millions could raise the risk of dying early, a large study suggests.

The drugs which are known as proton pump inhibitors, or PPIs - have previously been linked to a variety of health problems, including serious kidney damage, bone fractures and dementia.

The NHS issues more than 50 million prescriptions each year for the medication which is used to treat heartburn, ulcers and other gastrointestinal problems, but researchers say it may be time to restrict the use of the tablets.

The drugs also are available over the counter under brand names including Prilosec, Prevacid and Zegerid .

Researchers examined medical records of more than 275,000 PPI users and nearly 75,000 people who took another class of drugs - known as H2 blockers - to reduce stomach acid.