Blood thinners are usually prescribed for people who have conditions that affect healthy blood flow, including:
Atrial fibrillation, a type of irregular heart beat that can cause blood to pool in the top chambers of your heart, which can cause blood clots to form
Congenital heart defects, or heart problems that you are born with
Deep vein thrombosis, or a blood clot in a large vein, usually in your leg
Heart valve surgery
A history of heart attack or stroke
A history of blood clots