Researchers analysed data from nine trials, from a total of 102,621 patients. They said that while there was a 20% reduction in non-fatal heart attacks in people taking aspirin, there was no reduction in deaths from heart attack, stroke or cancer. Meanwhile the risk of potentially life threatening internal bleeding increased by 30%.

Lead researcher Prof Kausik Ray, from St George’s, University of London, told the BBC: “If you treat 73 people for about six years you will get one of these non-trivial bleeds. “If you treat about 160 people for the same period of time, you’re preventing one heart attack that probably wouldn’t have been fatal anyway. “It suggests that the net benefit for aspirin is not there, it certainly doesn’t prolong life. If you think about it the net benefit, actually there is net harm.”

The study followed patients for an average of six years. An analysis led by Prof Peter Rothwell, from Oxford University, suggested that regularly taking aspirin reduced the risk of a series of cancers, when patients were followed for much longer. Prof Rothwell said the new study was “very nicely done, but I don’t think it develops [the argument] much further”. He added: “It really just emphasises the need for a more detailed analysis of how risks change over time.”

Natasha Stewart, senior cardiac nurse at the British Heart Foundation, said: “Aspirin can help reduce the risk of heart attack or stroke among those with known heart disease, and this group of people should continue to take aspirin as prescribed by their doctor. “Our advice is that people who don’t have symptomatic or diagnosed heart disease shouldn’t take aspirin because the risk of internal bleeding may outweigh the benefits.