http://www.fda.gov/cder/consumerinfo/dailyaspirin_brochure.htm
Center for Drug Evaluation and Research, U.S. Food and Drug Administration
Aspirin has been shown to be helpful when used daily to lower the risk of heart attack, clot-related strokes and other blood flow problems. However, no medicine is completely safe. Talk to your doctor to learn whether the risks of long-term aspirin use may be greater than the benefits.