The cardiovascular system comprises the heart, blood vessels, and blood. Blood is made up of several components including: red blood cells, which carry oxygen; white blood cells or leukocytes, which fight infection; and platelets, also called thrombocytes, which assist in the formation of blood clots. Cholesterol and other fatty substances also circulate in the blood. The deposited cholesterol, or plaque, can build up over time, causing hardening and narrowing of the otherwise smooth artery walls. When a blood vessel is damaged due to plaque build-up, platelets repair it through a three-staged process called clotting. First, platelets attach to the injured vessel wall. Second, platelets release chemicals, such as adenosine diphosphate (ADP). ADP binds to receptors on platelets, changing other receptors to attract the molecule fibrinogen. Fibrinogen molecules make up fibrin which creates links between platelets. This structure traps red blood cells and other platelets to become a clot. Clotting occurs normally in the repair process. However, sometimes the amount of repairing platelets becomes too high. This can cause unnecessary clots to form. Clots make it harder for blood to flow and can result in cell death. Some risk factors for clot formation include: Coronary artery disease, obesity, smoking, genetic factors, and surgical recovery. Antiplatelet drugs can prevent unnecessary clots from forming. They work at different points during the clotting process. When taken orally, one such drug binds to ADP receptors, preventing other receptors from changing. As a result, fibrinogen does not link platelets together and a clot does not form, allowing blood to flow through the vessels. Antiplatelet drugs do not prevent plaque build-up which causes atherosclerosis. Please discuss with your doctor about taking cholesterol-lowering medications or any dietary changes which may be needed to treat this condition. As with all medications, side effects can occur. Excessive clot prevention can cause serious bleeding conditions. Therefore, it is important to discuss with your doctor before taking these medications.