A person holds two pills of aspirin in one hand and a glass of water in the other hand.For decades, the conventional wisdom held that regular use of aspirin could help reduce the risk of heart attack or stroke.

While this is still good advice for some, it’s not for everyone—and the restrictions only continue to tighten as it applies to aspirin as a preventative medicine.

Adults thinking about working aspirin into their diet should ask an important question: Does the reward outweigh the risk?

Health professionals offer a resounding “yes” on a daily dose for just one type of person: someone who has previously suffered a heart attack or stroke. These are people who use aspirin for secondary prevention of cardiovascular disease.

“There is no debate if you’ve had a heart attack or a stroke,” said Harland Holman, MD, medical director at the Spectrum Health Family Medicine Residency Center. “You should be on aspirin.”

A small daily dose of aspirin, about 81 milligrams, is a suitable starting point for a person to reduce the likelihood of experiencing another heart attack or stroke, Holman said, although he cautions that everyone should first consult a doctor on the matter.

Beyond this is what Dr. Holman and others consider a gray area regarding those people who may consider using aspirin to reduce the chance of heart attack or stroke even though they’ve never experienced such an event. They would be using the drug for what’s considered “primary cardiovascular disease prevention.”

This is a problematic group. If a person is at virtually no risk of cardiovascular disease, or even very low risk, he likely should not be taking a daily dose of aspirin, Dr. Holman said.

As an anti-platelet drug, aspirin keeps platelets from clumping, thus reducing the risk of blockages in blood vessels to the heart and brain. And, as with nearly every drug, there are inherent risks in the consumption of aspirin; in this case, gastrointestinal bleeding and hemorrhagic strokes.

“The biggest risk is that of gastrointestinal bleeding,” Dr. Holman said.

A study published recently in the Journal of American College of Cardiology found that many people simply do not meet the threshold considered acceptable to merit the daily use of aspirin. A person who wants to use aspirin for primary cardiovascular disease prevention should first consult a doctor, who can assess the overall risks and rewards.

“It helps to look at the whole big picture,” Dr. Holman said. “The thing called the Cardio Risk Factor.”

Resources abound to help people determine their Cardio Risk Factor, such as this risk assessment tool at the National Heart, Lung and Blood Institute website.  To determine individual risk of heart attack, the calculator factors in age, gender, cholesterol levels, blood pressure and whether someone is a smoker or non-smoker.

“There are a few out there,” Dr. Holman said. “You look at the overall risk … and kind of use that risk to decide if you want to use the aspirin.”

Doctors can use these pieces of information to tease out a reliable picture of a person’s health, roughly determining the odds a person will suffer a heart attack in the next 10 years.

But there is a risk factor a calculator simply cannot take into account. “Your family history,” Dr. Holman said, “which for aspirin is important. When you’re making a decision on this, you look at family history.”

This is where a doctor’s expertise is invaluable—a necessity, in fact, as it can help a person negotiate the endless if-then scenarios that seem to change with each new study. The FDA deviated from a long-held understanding that a daily aspirin was OK for many individuals at risk of a first-time heart attack. “The data do not support the use of aspirin as a preventative medication by people who have not had a heart attack, stroke or cardiovascular problems,” the FDA stated in a release.

On the other hand, a study in the Journal of American College of Cardiology found the use of aspirin to prevent heart problems is appropriate if someone stands more than a 1-in-20 chance of developing cardiovascular disease in the next 10 years. By this standard, according to the study, about 10 percent of people are using aspirin inappropriately.

There are other variables to consider.

“Tying into the debate, studies show (aspirin) can prevent colorectal cancer,” Dr. Holman said, which would indicate someone with a history of colon cancer may also benefit from regular use of aspirin.

Even in cases where there is a certain risk of stomach bleeding as a result of aspirin use, a person can still take aspirin, though accompanied by a stomach acid blocker such as Prilosec, Dr. Holman said. The benefits in such cases may simply outweigh the risks.

The findings in the latest and costliest studies can’t overshadow a core message from Dr. Holman and health care providers: Consult your doctor, no matter what your personal experience or family history. Dr. Holman cautioned he won’t advise a patient to use aspirin regularly—regardless of family history—until about age 40.