A bout 30 percent of adults in the U.S. age 65 and older report taking  aspirin daily to prevent a heart attack or stroke. This over-the-counter (OTC) pain reliever can be a lifesaver, but regular use may cause serious side effects, notably internal bleeding.

Here’s expert advice on who should and shouldn’t take daily aspirin, and if you do, how to take it safely.

Risks and Benefits of Daily Aspirin

Cardiovascular disease, or CVD, is often caused by narrowed arteries. Aspirin is an antiplatelet 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 aspirin significantly lowers the risk of a second cardiovascular event, says Marvin M. Lipman, M.D., Consumer Reports’ chief medical adviser.

More on heart health

The net benefits of daily aspirin use are less clear-cut for older adults who are only at moderate risk of CVD.

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 (GI) bleeding was highest in people age 75 and older.

However, the U.S. Preventive Services Task Force, an independent group that develops recommendations on preventive healthcare, says there is currently insufficient evidence to assess the benefits and harm of aspirin in adults age 70 and older.­­

“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.

Online calculators for GI bleeding risk and heart risk, such as Aspirin-Guide and Heart Risk Calculator, can help facilitate shared decision-making between you and your provider, she adds.

Using Daily Aspirin Safely

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 more after taking aspirin.

If you’re thinking about stopping your daily aspirin regimen, be sure to discuss it with your doctor first. Quitting suddenly may be risky for long-time 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 long-term 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 age 50 to 59 who also are at risk for CVD in the next 10 years and meet other criteria.

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, says Mora.

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

Editor's Note: This article also appeared in the February 2018 issue of Consumer Reports on Health