I can answer that question for you as a physician. The American College of Cardiology and the American Heart Association just updated the recommendations THIS YEAR. For the purposes of preventing a stroke or heart attack, the recommended dose of aspirin is between 75 and 162 mg/day, down from the previous guide of 75 to 325 mg/day. (A baby aspirin contains 81 mg and an adult aspirin contains 325 mg, so the recommendation calls for 1 to 2 baby aspirin a day.) This change is because all of our research suggests that the lower dose of aspirin is AS EFFECTIVE in reducing strokes and heart attacks as the higher dose and is LESS LIKELY to lead to serious bleeding. Having said that, you should consult your physician before starting any medications such as aspirin. For people with a history of ulcers or bleeding, aspirin may not be recommended OR may need to be started in conjunction with another medication to prevent bad side effects.