Daily aspirin is not a routine way to prevent a first heart attack or stroke. For some people with higher cardiovascular risk and low bleeding risk, it may offer a small benefit. For others, bleeding risk can outweigh that benefit. The decision depends on your health, age and medicines—not simply on whether aspirin is sold without a prescription.
What daily aspirin means for primary prevention
Primary prevention means trying to prevent a first cardiovascular event in someone who has not had one. Aspirin reduces the blood’s ability to form clots, which may help prevent some heart attacks and ischemic strokes. That same effect can make bleeding harder to stop, including bleeding in the stomach or, less often, the brain.
This is different from secondary prevention: treatment after a heart attack, ischemic stroke, transient ischemic attack or another established cardiovascular condition. Aspirin has a clearer role for many people in secondary prevention. If you take it because of a past event, a stent or another diagnosed condition, do not stop or change it without speaking to your clinician.
When daily aspirin may help—and when it may harm
The potential benefit depends partly on how likely you are to have a cardiovascular event without aspirin. When that starting risk is low, even a reduction in risk may prevent few events. The chance of bleeding still matters. Age, blood pressure, cholesterol, diabetes, smoking and other health factors can all shape the cardiovascular-risk estimate a clinician uses.
Three large randomized trials published in 2018 helped prompt more cautious recommendations: ASCEND studied people with diabetes but no known cardiovascular disease; ASPREE studied older adults; and ARRIVE studied people considered at moderate cardiovascular risk. Taken together, these trials reinforced that any cardiovascular benefit from aspirin for primary prevention may be offset by increased bleeding.
A clinician will also consider bleeding risks such as a history of stomach ulcers or bleeding, a bleeding disorder, chronic kidney disease, and use of medicines including anticoagulants, steroids or non-steroidal anti-inflammatory drugs (NSAIDs). These factors do not automatically determine the answer, but they can change the balance enough to make aspirin a poor choice.
Why age and regional guidance matter
In the United States, the 2022 U.S. Preventive Services Task Force recommendation says adults aged 40 to 59 with a 10-year cardiovascular risk of at least 10% may consider starting low-dose aspirin after an individual discussion; the expected net benefit is small. It recommends against starting aspirin for primary prevention at age 60 or older. The Task Force also says it may be reasonable to consider stopping around age 75, but that is not a reason to stop on your own.
U.S. cardiology guidance has a somewhat different age range: the American College of Cardiology and American Heart Association say aspirin may be considered for selected adults aged 40 to 70 at higher cardiovascular risk who are not at increased risk of bleeding. They advise against routine use in adults over 70. In Europe, the European Society of Cardiology advises against routine aspirin for people without established cardiovascular disease, while allowing consideration in some people with diabetes and high or very high cardiovascular risk.
These differences reflect how organizations weigh small possible benefits, bleeding harms and the groups most likely to benefit—not a guarantee that aspirin works differently across borders. Recommendations can change, and a threshold used in one country may not be the one used in yours. Ask a local clinician to assess your risk and explain which guidance applies to you.
What to discuss before starting or stopping
Do not start daily aspirin just because you are getting older or have heard that it “thins the blood.” Ask your clinician to review your cardiovascular risk, bleeding history and medicines together. If you take a blood thinner or regular NSAIDs, mention it; combining medicines that affect bleeding may raise concern. If you already take aspirin, check why it was prescribed before making a change. The balance for primary prevention is different from the balance after a heart attack or stroke.
For many people, attention to blood pressure, cholesterol, smoking and other modifiable risk factors is central to cardiovascular prevention. A clinician can help you understand how those factors affect your risk and whether aspirin adds enough potential benefit to justify its harms. This article cannot determine what is right for an individual; seek medical advice before starting or changing aspirin.
