For decades, low-dose aspirin, a 125-year-old drug primarily known as a painkiller, was widely embraced by over two million people in the UK daily, under the belief it offered crucial protection against heart attacks and strokes. Physicians often recommended it to middle-aged and older patients as a preventative measure, even in the absence of existing cardiovascular disease. However, a significant paradigm shift in medical thinking over the past two decades has challenged this long-held practice, revealing that for individuals without pre-existing cardiovascular conditions, the benefits of daily aspirin are limited, while the risks of severe side effects are considerably elevated.

The drug, whose origins trace back to the 1890s with its active compound salicin found in willow bark – used by Ancient Egyptians for pain and fever – was discovered in the 1960s to have anti-clotting properties. This blood-thinning effect, particularly in the tiny blood vessels of the heart and brain, made the 75mg "junior" or "baby aspirin" an inexpensive and seemingly effective preventative treatment against cardiovascular diseases, which account for approximately 175,000 UK deaths annually. By the early 2000s, nearly a quarter of older Britons were taking daily aspirin.

However, subsequent studies, particularly since 2009, began to raise serious concerns. Research indicated that prolonged aspirin use can irritate the stomach lining, leading to internal bleeding, dangerous stomach ulcers, and even life-threatening brain bleeds. The drug's anti-clotting mechanism, while preventing heart attacks and strokes, can impair the body's natural ability to stop other bleeds, such as those following a head injury. Some estimates suggest that at the peak of aspirin prescriptions in the early 2000s, related side effects might have contributed to around 7,000 deaths annually in the UK.

Consequently, medical guidance has been significantly tightened. In 2021, official recommendations were updated, advising patients to take daily low-dose aspirin only if explicitly recommended by their doctor. Further, in 2023, health officials proposed that GPs should no longer routinely offer aspirin for the primary prevention of a first heart attack. While the NHS continues to recommend low-dose daily aspirin for patients who have already suffered a heart attack or stroke, as the benefits demonstrably outweigh the risks in these cases, many healthy individuals remain unaware of the potential dangers.

Consultant cardiologist Prof Malcolm Finlay from Barts Heart Centre emphasizes that for those who haven't experienced a stroke or heart attack, the benefits of daily aspirin are minimal. He notes that while aspirin was a leading preventative drug in the 1970s, modern medicine now offers more effective and safer alternatives, such as blood pressure tablets and statins for cholesterol. Furthermore, lifestyle interventions like exercise and a healthy diet are powerful tools without the associated side-effect risks.

The serious consequences of daily aspirin use are underscored by numerous patient accounts. A 72-year-old woman, taking 75mg daily on GP advice, developed severe stomach pains and vomited blood while on a cruise. A 73-year-old man was hospitalized with a severe stomach bleed after five years of daily aspirin. Stuart Bailey, 78, underwent surgery for a severe brain bleed after a fall, which doctors believed was exacerbated by his long-term aspirin use for high blood pressure. Jane Whelan, 74, who took aspirin after a mini-stroke, suffered a burst stomach ulcer leading to severe internal bleeding, with doctors attributing it to aspirin. Even US President Donald Trump attributed large bruises on his hands to his daily 325mg aspirin dose, a known side effect.

Despite the accumulating evidence, some experts hold differing views. Professor Peter Elwood, an epidemiologist at Cardiff University, acknowledges that aspirin raises the risk of bleeds by about 50 percent but argues these are "rarely life-threatening" and that "there’s no strong evidence that aspirin kills people." He also points to a 2021 review of 118 studies suggesting aspirin may offer an anti-cancer benefit, with cancer patients taking aspirin being approximately 20 percent more likely to survive the disease, although the mechanism remains unclear and the risk of severe stomach bleeds still appears to outweigh the cancer benefit for most healthy individuals.

For patients with existing cardiovascular problems who require blood thinning, alternatives like warfarin or rivaroxaban are available. For those advised to take aspirin, "gastro-resistant" varieties are thought to be less damaging to the stomach. However, Prof Finlay highlights a concerning practice: GPs sometimes prescribe anti-acid drugs like omeprazole or lansoprazole alongside aspirin to mitigate stomach side effects. He warns that growing evidence suggests long-term use of these anti-acid drugs can increase the risk of stomach infections and bone fractures, reinforcing his stance that "aspirin and anti-acid drugs like omeprazole should not be taken long term."

Experts are now urging GPs to proactively warn healthy patients about the risks of daily aspirin. Many individuals, including those who have been on aspirin for years for conditions like angina or high blood pressure, express frustration at the lack of clear guidance and the persistence of severe side effects. The overarching message is clear: the widespread, routine use of aspirin for primary prevention is no longer supported by current medical evidence, and patients should critically evaluate its necessity with their doctor.