Overview

Factor V Leiden (FAK-tur five LIDE-n) is a mutation of one of the clotting factors in the blood. This mutation can increase your chance of developing abnormal blood clots, most commonly in your legs or lungs.

Most people with factor V Leiden never develop abnormal clots. But in people who do, these abnormal clots can lead to long-term health problems or become life-threatening.

Both men and women can have factor V Leiden. Women who carry the factor V Leiden mutation 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, anticoagulant medications can lessen your risk of developing additional blood clots and help you avoid potentially serious complications.