A spider vein is a condition in which the valves controlling blood flow or the walls of the veins become weak. The causes of spider veins are different under different circumstances. It generally affects women but men are also affected and the most commonly affected body parts are the legs and the thighs but it can affect the nose and the face also.

Some of the common causes of spider veins are aging, hormonal imbalance, smoking, drinking, obesity, occupational hazards and poor blood circulation. Spider veins can also be caused by over exposure to sun and heredity also plays a major role in some cases.