For most healthy adults, taking low-dose aspirin daily is no longer recommended as a preventive measure. Guidelines shifted significantly in 2022, when the U.S. Preventive Services Task Force recommended against starting daily aspirin for heart disease prevention in adults 60 and older, and called it an individual decision for adults 40 to 59 with elevated cardiovascular risk. The reason: the bleeding risks often outweigh the benefits, especially as you age.
That said, the answer depends heavily on whether you already have heart disease or are trying to prevent it from developing in the first place. Those two situations carry very different risk-benefit profiles.
How Low-Dose Aspirin Works
Low-dose aspirin, typically sold as 81 mg tablets in the U.S., works by permanently disabling an enzyme in your platelets called COX-1. That enzyme is needed to produce a chemical that makes platelets clump together and form clots. Since platelets can’t repair themselves, a single dose of aspirin keeps each affected platelet from clotting for the rest of its roughly 10-day lifespan. This is why even a small daily dose has a cumulative, powerful effect on your blood’s ability to clot.
That anti-clotting action is exactly why aspirin can both help and harm. It reduces the chance of a clot blocking an artery to your heart or brain, but it also makes it harder for your body to stop bleeding when it needs to.
Who Still Benefits From Daily Aspirin
If you’ve already had a heart attack, stroke, or been diagnosed with cardiovascular disease, daily aspirin remains a standard part of treatment. This is called secondary prevention, and the benefits here are well established and substantial.
For people without existing heart disease (primary prevention), the picture is much murkier. The USPSTF says adults aged 40 to 59 who have a 10% or greater chance of a cardiovascular event in the next 10 years can consider aspirin, but only after weighing the tradeoffs with a clinician. Your 10-year risk is calculated based on factors like blood pressure, cholesterol, smoking status, and diabetes.
For adults 60 and older who have never had a heart attack or stroke, the task force recommends against starting aspirin. The conclusion, stated plainly: initiating aspirin use in this age group has no net benefit. For people in their 70s, modeling shows aspirin initiation actually results in a net loss of both life-years and quality-adjusted life-years at essentially every cardiovascular risk level studied.
The Bleeding Risks
The most significant danger of daily aspirin is bleeding, particularly in the digestive tract and brain. A systematic review for the USPSTF found that daily aspirin (at doses ranging from 50 to 500 mg) increased the risk of major gastrointestinal bleeding by 59% compared to not taking it. That includes bleeding serious enough to require hospitalization or transfusion.
Brain bleeding is rarer but more dangerous. A study from the National Institute on Aging found that daily low-dose aspirin increased brain bleeding events by 38%, regardless of gender, age, or baseline cardiovascular risk. The same study found no statistically significant difference in overall stroke rates between people taking aspirin and those on placebo, meaning aspirin’s ability to prevent one type of stroke (caused by clots) was essentially offset by its tendency to cause another type (caused by bleeding).
These bleeding risks climb as you get older. The absolute incidence of bleeding increases with age, which is the core reason the guidelines now discourage starting aspirin after 60 for primary prevention.
Aspirin and Cancer Prevention
Earlier guidelines from the USPSTF, issued in 2016, suggested that daily aspirin could help prevent colorectal cancer in adults aged 50 to 59 who were already taking it for heart protection. That potential benefit was part of the original rationale for some people. However, the updated 2022 recommendation no longer includes colorectal cancer prevention as a reason to start aspirin. The evidence wasn’t strong enough to maintain that recommendation as a standalone benefit.
Dangerous Combinations With Other Medications
Daily aspirin becomes riskier when combined with other drugs that affect clotting or irritate the stomach lining. Common over-the-counter pain relievers like ibuprofen and naproxen (NSAIDs) affect how platelets work and can interfere with normal clotting on their own. Taking them alongside aspirin compounds the bleeding risk, especially in the digestive tract.
Prescription blood thinners like warfarin or newer oral anticoagulants work through a different mechanism than aspirin, lengthening the time it takes blood to clot rather than targeting platelets directly. Combining these with aspirin raises bleeding risk even further. If you’re on any blood-thinning medication, adding daily aspirin without medical guidance introduces real danger.
Why You Shouldn’t Stop Abruptly
If you’ve been taking daily aspirin for a long time, stopping suddenly carries its own risk. A large study published in the American Heart Association’s journal Circulation found that people who discontinued long-term low-dose aspirin (without a reason like major surgery or a bleeding event) had a 37% higher rate of cardiovascular events compared to those who continued. That translated to roughly one additional cardiovascular event per year for every 74 people who stopped.
The increased risk appeared shortly after discontinuation and didn’t diminish over time. This rebound effect is thought to occur because the body’s clotting system, long suppressed by aspirin, ramps back up. If you’re considering stopping, tapering or transitioning under medical guidance is safer than quitting cold turkey.
The Bottom Line by Age Group
- Under 40: Daily aspirin for heart prevention is not recommended for most people in this age group, as cardiovascular risk is generally too low to justify the bleeding trade-off.
- 40 to 59: If your 10-year cardiovascular risk is 10% or higher, daily low-dose aspirin may offer a small net benefit. This is an individual decision that depends on your specific risk factors and bleeding history.
- 60 and older (no prior heart disease): Starting daily aspirin is not recommended. The bleeding risks at this age consistently outweigh the cardiovascular benefits in people who haven’t already had a heart event.
- Any age with existing heart disease: Daily aspirin typically remains beneficial and is considered standard care. Stopping it without guidance can be harmful.
The shift in guidelines reflects better data, not a change in aspirin itself. Newer, larger trials showed that the benefits in otherwise healthy people were smaller than earlier studies suggested, while the harms, particularly bleeding, were consistent and significant. What changed is our understanding of who truly benefits and who is better off without it.