Aspirin is no longer recommended as a routine way to prevent heart attacks and strokes in people who have never had one. In 2022, the U.S. Preventive Services Task Force officially recommended against starting daily aspirin for adults 60 and older, reversing decades of conventional wisdom. The shift came after three large clinical trials showed that for otherwise healthy people, aspirin’s bleeding risks largely cancel out its heart benefits.
This change applies specifically to “primary prevention,” meaning taking aspirin to avoid a first cardiovascular event. If you’ve already had a heart attack, stroke, or stent procedure, aspirin is still a standard part of treatment.
What the New Guidelines Say
The USPSTF now breaks its recommendation into two age groups. For adults 60 and older, the task force recommends against starting low-dose aspirin for heart disease prevention, concluding with moderate certainty that it offers no net benefit in this group. For adults 40 to 59 who have a 10% or greater chance of a cardiovascular event in the next decade, aspirin is no longer a default recommendation. Instead, it’s framed as an individual decision to make with a doctor, and only for those at elevated risk.
The American Heart Association and American College of Cardiology landed in a similar place. Their 2019 guideline states bluntly that aspirin “should be used infrequently in the routine primary prevention” of cardiovascular disease because of its lack of net benefit. For adults over 70, they call routine prophylactic aspirin “potentially harmful.”
The Three Trials That Changed Everything
For years, aspirin’s reputation as a heart-protective drug rested on older studies conducted when smoking rates were higher, statin use was rare, and blood pressure management was less aggressive. Three major trials published in 2018 tested whether aspirin still made sense in a modern medical landscape. The results were consistent and sobering.
The ASPREE trial enrolled over 19,000 healthy adults aged 70 and older and gave them either 100 mg of aspirin or a placebo daily. Aspirin provided no survival benefit. In fact, all-cause mortality was higher in the aspirin group, with cancer as a major contributor to the increased deaths.
The ASCEND trial focused on more than 15,000 patients with diabetes, a group long thought to benefit from preventive aspirin. Aspirin did reduce the risk of a first cardiovascular event, but the benefit was largely counterbalanced by serious bleeding events requiring hospitalization. Researchers could not identify any subgroup of diabetic patients in whom the benefits clearly outweighed the risks.
The ARRIVE trial tested aspirin in a general population at moderate cardiovascular risk. Aspirin simply did not reduce the occurrence of major cardiovascular events.
Bleeding Risk Is the Core Problem
Aspirin works by making blood platelets less sticky, which helps prevent the clots that cause heart attacks and strokes. But that same mechanism makes bleeding more likely, particularly in the stomach and intestines. A detailed analysis from the ASPREE trial found that daily low-dose aspirin increased the risk of serious gastrointestinal bleeding by 60% in healthy adults 70 and older.
This isn’t minor stomach irritation. The bleeding events in these trials were serious enough to require hospitalization. Intracranial bleeding, though rarer, is another concern. The risk of these complications rises with age, which is exactly why the strongest recommendation against aspirin targets older adults. The people most likely to have a heart attack are also the people most likely to bleed dangerously from aspirin.
The Cancer Prevention Angle Fell Apart Too
For a period, aspirin was also promoted as a way to reduce colorectal cancer risk. The USPSTF previously suggested that adults aged 50 to 59 could benefit from aspirin for both heart disease and cancer prevention. But the newer evidence hasn’t supported this. The ASCEND trial found no reduction in colorectal cancer risk over its average seven-year follow-up. The ASPREE trial was more alarming, finding that cancer contributed to the higher death rate in the aspirin group. The current USPSTF recommendation no longer includes colorectal cancer prevention as a reason to start aspirin.
When Aspirin Is Still Essential
None of this applies to people who have already experienced a cardiovascular event. If you’ve had a heart attack, undergone bypass surgery or a stent procedure, or been diagnosed with significant coronary artery disease, guidelines still recommend 75 to 100 mg of aspirin daily. This is called secondary prevention, and the evidence supporting it remains strong. In this population, the risk of another heart attack or stroke is high enough that aspirin’s clot-preventing benefits clearly outweigh its bleeding risks.
A large pragmatic trial of 15,000 patients with established cardiovascular disease compared 81 mg and 325 mg doses and found no difference in effectiveness or safety, which is why the lower dose has become standard.
Do Not Stop Aspirin on Your Own
If you’re currently taking daily aspirin because of a prior heart attack, stent, or other cardiovascular condition, stopping abruptly can be dangerous. Suddenly discontinuing aspirin therapy can trigger a rebound effect where blood becomes more prone to clotting, potentially leading to a heart attack. Any change to an existing aspirin regimen should be a conversation with the prescribing doctor, not a decision made after reading about updated guidelines.
What Replaced Aspirin for Prevention
The decline of aspirin for primary prevention didn’t leave a gap. Modern cardiovascular prevention relies on a combination of approaches that are both safer and more effective. Statins have become the first-line medication for people with elevated cholesterol, diabetes (ages 40 to 75), or high enough cardiovascular risk to warrant treatment. Unlike aspirin, large-scale trials consistently show that statins reduce cardiovascular risk in primary prevention with benefits that outweigh observable risks.
Beyond medication, current guidelines emphasize that lifestyle is the most important tool for preventing heart disease, heart failure, and irregular heart rhythms. The specific recommendations: at least 150 minutes per week of moderate-intensity exercise (or 75 minutes of vigorous activity), a diet rich in vegetables, fruits, nuts, whole grains, lean protein, and fish while limiting processed red meat, trans fats, and sugary drinks. Blood pressure management, with a general target below 130/80, is another pillar. For people with type 2 diabetes, newer classes of glucose-lowering medications offer cardiovascular protection that aspirin never reliably provided.
The broader picture is that cardiovascular medicine has simply gotten better at prevention through other means. When aspirin was first championed for heart health, fewer people were on statins, blood pressure control was less precise, and smoking was more common. Today, the baseline risk of a first heart attack is lower for many people, which shrinks aspirin’s potential benefit while its bleeding risk stays the same.