Illustration of white pills and red hearts.

Nearly 30 million Americans who are 40 or older—who don’t have cardiovascular disease—take aspirin every day anyway, with the aim of protecting their hearts. Of these, 6.6 million do it without any recommendation from their doctor, according to new research published online today in the Annals of Internal Medicine.

That’s concerning, the researchers say: This over-the-counter (OTC) pain reliever can be a lifesaver—helping to reduce the likelihood of heart attack or stroke for some people, especially in those with known heart disease. But regular use may cause serious side effects, notably internal bleeding.

Until fairly recently, many members of the medical community supported the use of daily low-dose aspirin as a way to prevent a first heart attack or stroke—considered primary prevention. But in the past few years, new research has emerged showing that for many people without diagnosed heart disease, the risk of bleeding may outweigh the benefits of daily aspirin.

More on heart health

This is especially true for older adults. In fact, guidelines released by the American Heart Association (AHA) and the American College of Cardiology (ACC) in March recommend against daily use of aspirin to prevent a first heart or stroke in people older than 70 (and in adults of any age who are at increased internal bleeding risk).

Before 2019, the AHA offered no specific guidelines for adults older than 70. Instead, the organization recommended low-dose daily aspirin for all adults with a high 10-year risk of heart disease. 

And previously, the U.S. Preventive Services Task Force (USPSTF), an independent group that develops recommendations on preventive healthcare, said there was insufficient evidence to assess either the benefits or harms of aspirin in adults 70 and older.

What follows is expert advice on who should—and who shouldn’t— take daily aspirin, and for those who should, how to take it safely.

Risks and Benefits of Daily Aspirin

Cardiovascular disease, or CVD, is often caused by narrowed arteries. Aspirin is an anti-platelet medication. That means it prevents platelets (a type of blood cell) from clumping together and forming blood clots in those arteries.

For people with established CVD, especially those who have already had a heart attack or stroke, there’s strong evidence that taking a daily low-dose aspirin significantly lowers the risk of a second cardiovascular event.

If you’re in this group, “do not stop taking your daily aspirin unless advised to do so by your physician,” says Guy L. Mintz, M.D., director of cardiovascular health and lipidology at Sandra Atlas Bass Heart Hospital in Manhasset, N.Y.

The net benefits of daily aspirin use are less clear-cut for older adults who are at only moderate risk of CVD. (Your doctor can help you determine your risk.) 

Here’s why: Although age can boost the likelihood of cardiac events that may be prevented by daily aspirin use, it can also raise the risk of internal bleeding. A study published in The Lancet in June 2017, for instance, showed that the risk of serious, potentially fatal, gastrointestinal bleeding was highest in people 75 and older.

And three randomized controlled trials published in 2018 showed few heart benefits from daily aspirin use but an increase in internal bleeding risk for those using the drug for primary prevention. One of the studies focused on adults at average risk of heart disease, a second on adults older than 70, and the third on people with diabetes.

In part because of these 2018 studies, the 2019 AHA/ACC guidelines now recommend that aspirin not be used daily for the primary prevention of heart attack or stroke in two groups: all people older than 70 and, as older guidelines did, adults at higher risk of internal bleeding—such as those with peptic ulcers. 

What about people between ages 40 and 70? The new guidelines says that those in this age group who have no known heart disease but do have conditions that increase their likelihood of heart attack and stroke—such as type 2 diabetes—may be considered for daily low-dose aspirin. But that’s only if they don’t have an increased likelihood of bleeding and if their cumulative risk is high enough. 

But as the new Annals of Internal Medicine study suggests, many people for whom daily aspirin is not advised may be taking it. The researchers estimate that 23.4 percent of all U.S. adults 40 and older without heart disease (including nearly half of all adults 70 and older with no known heart disease) use daily aspirin for prevention. Of those, 22.8 percent do so without the recommendation of their doctor.

The study also found that people with peptic ulcers, which hike the risk of internal bleeding, were no less likely to use daily aspirin than other people. 

“The findings don’t necessarily mean that people—and doctors—aren’t following the new recommendations,” says senior study author Christina Wee, M.D., associate professor of medicine at Harvard Medical School and director of the Obesity Research Program at Beth Israel Deaconess Medical Center in Boston. That’s because the study, which queried 14,328 U.S. adults about their aspirin use, was conducted in 2017, prior to the new research and guidelines.

But what the study does show, Wee says, is that a concerningly large number of older Americans may be taking daily aspirin, sometimes on their own.

Using Daily Aspirin Safely

What should you do? “The best approach is to have a discussion with your healthcare provider about the potential risks and benefits of aspirin therapy for you specifically,” says Samia Mora, M.D., a cardiologist at Brigham and Women’s Hospital in Boston.

If you and your doctor determine that daily aspirin is appropriate for you, take smart steps. Because the risk of bleeding rises with dosage, take the lowest possible amount. “For most people, that’s an 81 mg ‘baby aspirin,’ ” Mora says.

Your doctor may also recommend the use of a medication known as a proton pump inhibitor (PPI), such as lansoprazole (Prevacid and generic) and omeprazole (Prilosec and generic), or an antacid—especially if you’re at higher risk for internal bleeding (this includes those with a history of ulcers, clotting disorder, or heavy alcohol use) but need daily aspirin for the protection of your heart.

PPIs help safeguard against gastrointestinal bleeding. But regular use has been linked to increased susceptibility to hip fracture and serious bacterial infections, such as Clostridium difficile and pneumonia.

Some OTC painkillers, such as ibuprofen (Advil and generic), can interfere with aspirin’s heart-protecting action. So for pain relief, use acetaminophen (Tylenol and generic) instead. If you must use ibuprofen, the Food and Drug Administration says it’s best to wait 30 minutes or longer after taking aspirin.

If you’re thinking about stopping your daily aspirin regimen, be sure to discuss it with your doctor first. Quitting suddenly could be risky for longtime users. A Swedish study published in September 2017 in the journal Circulation found that those who did faced a 37 percent increased risk of heart attack or stroke.

What About Cancer Protection?

The longterm use of daily low-dose aspirin appears to lower the risk of colorectal cancer. But the task force doesn’t recommend it solely for cancer prevention.

It recommends low-dose daily aspirin for the prevention of CVD and colorectal cancer only for people ages 50 to 59 who also are at risk for CVD in the next 10 years and meet other criteria. Adults between age 60 and 69 who meet certain criteria—such as a life expectancy of at least 10 years and not being at higher risk of bleeding—may also benefit, thought the USPSTF says aspirin therapy in this group should be an individual choice.

Other ways to cut your risk of colorectal cancer include regular exercise, quitting smoking, and upping your intake of fruits and vegetables while cutting red and processed meats from your diet, Mora says.

If you have a strong family history of colorectal cancer, Mora suggests that you talk to your doctor about appropriate strategies. 

Editor’s Note: A version of this article appeared in the February 2018 issue of Consumer Reports On Health. It was updated July 22, 2019, to reflect new guidelines and research.