What Are Spider Veins?

Spider veins are the thread-like red and purple blood vessels that occur in patches on the legs and face. They are often as delicate as a spider's web, which is how they get their name. The patches also resemble tiny sunbursts, tree branches or just plain lines.

Spider veins (referred to medically as telangiectasias) and varicose veins aren't the same. Varicose veins are large, swollen and occur singularly on the legs. Spider veins are much more delicate, tend to develop in clusters anywhere on the body, and are caused by irregular blood flow. They are thought to be induced by hormones and are often associated with pregnancy and menstruation. Although spider veins generally don't have symptoms, the veins deeper in the skin that feed them may cause discomfort. Women are more likely than men to get spider veins. Exactly what happens in the body that leads to spider veins isn't certain.

Considered a cosmetic problem, spider veins don't pose a health threat, though sometimes the deeper veins feeding them are associated with aching and discomfort. Spider veins usually take on one of three basic patterns:

  • Thin separate lines - linear
  • Tiny branch-like shapes
  • A true spider-like shape radiating outward from a dark center

Linear spider veins are commonly seen on the inner knee, whereas the arborizing (branch- or spider-like) patterns often appear on the outer thigh in the form of a sunburst.