You might want to stop taking an aspirin daily if you don't have a history of heart disease, according to a new study by Harvard researchers.

The study shows that aspirin may not reduce the risk of a heart attack in people with no prior history. Researchers also found that the drug could cause other side effects such as digestive tract bleeding.

According to the Harvard study, 29 million people ages 40 and up take aspirin every day, even though they have no history of heart disease.

Nearly seven million of them take aspirin without a doctor's recommendations.

Dr. Evelina Grayver is a cardiologist at North Shore University Hospital in Manhasset. She says patients should talk to their doctors before making any changes.

"The study showed there were people taking the drug that had an increased risk of bleeding that does occur," says Grayver. "But there's the other side, the side of the patients that have such high-risk factors or have truly proven heart disease with coronary stents that should never ever stop aspirin."

The Harvard study does say you should still take aspirin if you have a history of heart disease. Doctors say healthy eating and exercise are always good ways to reduce your chance of a heart attack.