Once just a handy pain reliever, aspirin has come to be seen as a powerful little pill that in some cases can reduce the risk of heart attack and stroke. Now we have reason to believe it might even lower the chances of developing cancer. Recent research from Harvard revealed that long-term aspirin use was associated with a 25 percent lower risk of colorectal cancer and a 14 percent reduced risk of stomach and esophageal cancers. And in case those stats aren't appealing enough, the U.S. Preventive Services Task Force—a medical organization that doesn't give advice lightly—has proposed that adults ages 50 to 59 with an elevated risk of heart disease take a low-dose aspirin (81 milligrams) daily to help prevent heart attacks, strokes and possibly colon cancer. But here's where things get a little tricky: Aspirin is a blood thinner that increases the risk of stomach bleeding, and it has even been linked to higher risk of hemorrhagic stroke (which occurs when a blood vessel in the brain ruptures). So should you take the pill regularly or not? Answer these questions first:

What's your risk of developing heart disease in the next ten years?

The U.S. Preventive Services Task Force review found that the benefits of aspirin outweigh the dangers of internal bleeding only for people whose ten-year likelihood of developing cardiovascular disease is 10 percent or higher. You can estimate your risk with the ASCVD Risk Estimator, a smartphone app from the American College of Cardiology and the American Heart Association, though your doctor should ultimately make the call.

Do you have a history of gastrointestinal bleeding or trouble with blood clotting?

If the answer is yes, you may want to pass on a daily aspirin to avoid increasing your chances of internal bleeding and ulcers. In fact, one study found that for every 133 women taking aspirin every other day, one would suffer a major bleeding episode (requiring hospitalization), and one out of 29 would have milder bleeding or ulcers. If you already suffer from clotting issues, aspirin could be dangerous.

Are you interested in aspirin only for the cancer benefits?

The Harvard scientist who led the study linking aspirin and lowered cancer risk has pointed out that while the findings are compelling, reduced probability of certain cancers is an extra benefit but should not be the primary reason for taking aspirin regularly. Until more is known, don't pop the pill without talking to your doctor first—even if cancer runs in your family.

Have you been protecting yourself from heart disease in other ways?

If your doctor does decide that a daily low-dose aspirin is a smart move for you, remember: Aspirin is not a foolproof defense against heart attack or stroke. You should still exercise regularly, maintain a healthy diet and weight, and refrain from smoking. It's also important to recognize that you're in this for the long haul. The preventive benefits of aspirin on heart disease may take up to five years to have an effect, so don't skimp on pill-free habits that can also help in the short term.

Mehmet Oz, MD, is the host of The Dr. Oz Show (weekdays; check local listings).

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