A: Aspirin inhibits blood clotting by reducing the “stickiness” of platelets. This helps lower the incidence 
of stroke and heart attacks, but may increase the risk of bleeding. In general, people at low risk of having a heart attack or stroke shouldn’t take daily aspirin because the chance of bleeding outweighs any potential benefit. In contrast, low-dose aspirin therapy is beneficial for those who carry an increased risk of heart attack or stroke, including people with the irregular heart rhythm called atrial fibrillation.

Low-Dose Aspirin for Heart Health The Saturday Evening Post