Varicose veins are twisted, enlarged veins near the surface of the skin. They are most common in the legs and ankles. Varicose veins usually aren't serious. In rare cases, they may be a sign of a more serious problem that may need treatment, such as deep vein thrombosis.
Varicose veins are caused by weakened valves and veins in your legs. Normally, one-way valves in your veins keep blood flowing from your legs up toward your heart. When these valves don't work as they should, blood collects in your legs, and pressure builds up. The veins become weak, large, and twisted.
Varicose veins often run in families. You may be born with defective valves or weak walls in your veins, or you may develop them later in life.
Varicose veins are more common in women than in men. And they happen more often as people get older.
Varicose veins often form during pregnancy. They might become less prominent after pregnancy and may disappear completely.