Factor V Leiden (FAK-tur five LIDE-n) is a mutation of one of the clotting factors in the blood called factor V. This mutation can increase your chance of developing abnormal blood clots (thrombophilia), usually in your veins.

Most people with factor V Leiden never develop abnormal clots. However, some people with factor V Leiden develop clots that lead to long-term health problems or become life-threatening.

Both men and women can have factor V Leiden, but women may have an increased tendency to develop blood clots during pregnancy or when taking the hormone estrogen.

If you have factor V Leiden and have developed blood clots, medications can lessen your risk of developing additional blood clots and help you avoid potentially serious complications.

Sep. 06, 2012