In women, aspirin prevents strokes and doesn't have any real effect on heart attack, and in men aspirin prevents heart attacks but has no effect on the prevention of strokes. So there appears to be a gender-based difference in the beneficial effect of aspirin.

Aspirin affects platelets differently in men and women.

In both men and women, there was an approximately 70 percent increase in the risk of bleeding associated with the taking of aspirin. And it is known that the bleeding risk associated with aspirin is dose-related.

While our analysis showed that aspirin may have different effects in men and women, the relatively small number of heart attacks among women and strokes among men suggest that more research is needed to better understand any differences in cardiovascular response to aspirin.

Aspirin prevents the blood in the body from clotting, and because stroke and heart attack are both caused by the formation of blood clots in the body, anything that prevents blood clotting from forming would be expected to have a beneficial effect in those diseases.

Women often have atypical symptoms of heart attacks when compared to men.