Daily aspirin for primary prevention can do more harm than good. New guidelines from the American College of Cardiology and the American Heart Association say healthy adults without known heart disease should no longer take a daily aspirin to prevent a heart attack. The new guidelines reflect the findings of several major studies published recently in the New England Journal of Medicine, which showed that low-dose aspirin did not extend life in otherwise healthy older adults and any preventive benefits were offset by the danger of internal bleeding and other adverse effects in people considered to be at low or moderate risk for heart disease. To read the guidelines, go to http://www.ahajournals.org/doi/pdf/10.1161/CIR.0000000000000678.