Key takeaways

Daily low-dose aspirin has been traditionally recommended to prevent cardiovascular events, but recent studies and revised guidelines suggest it may not benefit healthy individuals and could pose risks.
The American Heart Association and the American College of Cardiology now advise against daily aspirin use for primary prevention in certain groups due to the potential for increased bleeding, particularly in healthy older adults and those with bleeding risks.
Aspirin remains recommended for individuals with a history of heart disease or those who have had a heart attack or stroke, as it can significantly reduce the risk of a second cardiovascular event.
It’s important for individuals, especially those aged 40 to 59 or with major risk factors for heart disease, to consult with their healthcare provider before starting or stopping aspirin therapy to weigh the benefits against the risks.

Taking a low-dose daily aspirin has long been recommended by cardiologists as an easy and effective way to help prevent cardiovascular events such as heart attacks and strokes, which are the leading killers in the United States. Aspirin has blood-thinning abilities and fights the formation of blood clots that can block blood flow in the arteries and lead to cardiovascular disease.

Two recently published studies, known as ASCEND and ARRIVE, have called this recommendation into question, especially for the millions of healthy people who use aspirin as a way to reduce their risk of having a first-time heart attack or stroke. In light of these studies, the American Heart Association (AHA) and the American College of Cardiology (ACC) have recently revised their recommendations on daily aspirin use, noting that for many Americans, especially healthy older adults and those with bleeding risks, the dangers outweigh the benefits.

“There’s research showing more death and more bleeding with no reduction in cardiovascular events in healthy individuals taking a daily aspirin,” says Erin Michos, MD, MHS, the associate director of preventive cardiology at Johns Hopkins University School of Medicine who also served on the writing committee for the 2019 AHA/ACC Guideline on the Primary Prevention of Cardiovascular Disease. “In people without a history of heart disease or without certain risk factors for it, daily aspirin use can do more harm than good.”

On Oct. 13, 2021, a federal advisory panel said people over the age of 60 should not start taking aspirin for heart disease because the risk of bleeding outweighs the benefits. People ages 40 to 59 should discuss it with their clinicians.

Daily aspirin and heart disease

Most heart attacks and strokes are the result of blocked blood flow, according to the AHA. This occurs when plaque—a fatty substance made up of cholesterol, cellular waste, calcium, and other products—builds up on artery walls. Plaque narrows the arteries making it harder for blood to pass through. Ruptured plaques can also trigger the formation of blood clots that can lodge in arteries and clog them. When blood flow to the heart is affected, heart attacks can happen. If blood flow to the brain is restricted, a stroke can occur.

Aspirin is technically known as an antiplatelet medication. Platelets are tiny blood cells that help your blood clot. Aspirin thins blood and interferes with its clotting mechanism, making it less likely blood clots will form and clog arteries. While some studies have suggested that aspirin can lower blood pressure (having high blood pressure is a risk factor for cardiovascular disease), experts caution that the studies have not been well-conducted and the results have been conflicting.

Benefits of daily aspirin use

One in five people who have had one heart attack will be hospitalized with another one within five years, reports the AHA. Doctors recommend low-dose aspirin use in people with a history of heart disease because research—some 200 studies in over 200,000 people—shows it reduces the chances of having a second cardiovascular event. One of the first studies pointing to a connection was printed in the Lancet in 1988 and showed that one month of low-dose aspirin use started immediately after a heart attack or stroke could prevent 25 deaths in 1,000 patients and 10-15 nonfatal cardiovascular events.

What are some other benefits of aspirin?

It appears to reduce the incidence of certain cancers, particularly colon cancer, but more research is needed.
It’s widely available and fairly inexpensive.

Risks of daily aspirin use

Aspirin may seem like a harmless enough drug, but, in fact, its use carries side effects.

According to research published in the journal PLoS One, the use of aspirin increases a person’s risk of gastrointestinal bleeding by 40%. And while you might think some intestinal bleeding is preferable to a major heart attack, think again.

“There are certainly good reasons to take aspirin, but it’s not a completely benign drug,” notes Christina Wee, MD, MPH, an assistant professor of medicine at Harvard Medical School and co-author of a recent article published in the Annals of Internal Medicine on the prevalence of aspirin use for the primary prevention of cardiovascular disease. “If you’re middle aged or younger and healthy, a bleeding ulcer may be something you can recover from. But if you’re frail or an older adult with underlying issues, that bleeding ulcer can cause you to lose a lot of blood, which could actually precipitate a heart attack seeing as your heart now has to pump much harder to get oxygen-carrying blood to your system.”

“Gastrointestinal bleeding can be major,” adds Dr. Michos. “It can lead to anemia, and it can put a lot of stress on your heart. Bleeding is not a trivial thing. It can cause a lot of morbidity and mortality.”

Because of this increased bleeding risk, the AHA/ACC guidelines on the primary prevention of cardiovascular disease have changed with respect to aspirin use. While it’s still advised that those who’ve already had a heart attack or stroke use a daily low-dose aspirin to prevent another cardiovascular event (ditto those who have stents or had bypass surgery) things are different for those who don’t have heart disease. The new guidelines now advise against using aspirin to prevent a heart attack or stroke in certain groups who have a high risk of internal bleeding.

Higher risk patients include:

those who are 70 and over who are trying to prevent a first heart attack or stroke
those of any age who have conditions (such as ulcers) or take drugs (such as anticoagulants or nonsteroidal anti-inflammatories, or NSAIDS, such as ibuprofen) that can raise their bleeding risk.

What if you don’t have diagnosed heart disease but you have some major risk factors for it—for example, you smoke or have diabetes? Aspirin use may be appropriate, but you’ll need your doctor’s help in assessing and defining your actual risk. If you’re advised to quit taking aspirin, don’t worry about health risks. Stopping aspirin cold turkey shouldn’t pose any dangers, says Dr. Michos.

How much aspirin should you take a day?

Most of the studies surrounding aspirin and heart attack prevention focus on daily low-dose aspirin (sometimes referred to as “baby aspirin,” which is a misnomer since babies should not generally take aspirin), defined as 75-100 mg per day. According to research published in the BMJ, this lower dose was found to be as effective as higher doses in preventing secondary heart attacks and strokes.

But before you reach for a tablet, have a discussion with your healthcare provider. Your medical history may make you an inappropriate candidate for daily aspirin therapy, or your doctor may think you’ll be better served by statins and other drugs that treat heart disease.

“Using aspirin or not is something you need to talk about with your physician,” cautions Dr. Michos. “Just because a drug like aspirin is available over the counter does not mean it’s safe or appropriate. Discuss everything you take with your doctor.”