Ticlopidine is a drug that acts on platelets, the tiny cells in the bloodstream that help blood to clot. Ticlopidine is therefore sometimes used to reduce the risk for strokes by preventing clotting in patients whose arteries leading to the brain are greatly narrowed. It is also used to prevent clots from blocking cardiac stents (tunnel-like devices that are sometimes used to open narrowed blood vessels in the heart), thus cutting down the risk of heart attacks. Thrombotic thrombocytopenic purpura (TTP) is a medical condition that can occur on its own, but it has also been reported as a side effect of ticlopidine. TTP, a potentially serious and sometimes fatal illness, includes kidney problems, fever, bleeding, confusion, and seizures. It is not known how ticlopidine leads to TTP. However, in cases of TTP not related to a drug, a substance found normally in the bloodstream that helps blood to clot (called von Willebrand factor) is involved.