The Food and Drug Administration is recommending against taking an aspirin a day to prevent a heart attack.
FDA researchers say the risk of internal bleeding is the primary concern.
"Bleeding from the stomach is quite common, more rarely bleeding in the brain. So, if you have a low risk of a heart attack then the bleeding risk may overwhelm any potential benefit of aspirin," Dr. Steve Nissen said.
Doctors say aspirin thins the blood, which would make it less likely to clot.
Clotting is associated with heart attacks, so the logic was taking an aspirin a day would help to prevent heart attacks.
But researchers say they've carefully examined major studies and conclude the data does not appear to support the use of aspirin as a preventative medication by people who have not had a heart attack, stroke, or cardiovascular problems.
There're only a select few who may benefit from aspirin therapy.
"It's somebody that has every risk factor: high blood pressure, high cholesterol, strong family history, diabetes, if you have all of those things- smoking. If you have all of those risk factors, then some of those people we will treat with aspirin, but it's not very many," Dr. Nissen said.
Even if you only have one of the risk factors, like a strong family history, FDA researchers say the data does not show a benefit from aspirin therapy.
They say their recommendation applies to doses ranging from 80 milligrams in a low-dose tablet to the 325 milligrams in a regular strength tablet.
If you're taking aspirin to prevent a heart attack and have never had heart disease, or a heart attack before- stop and talk to your doctor