Thread or ‘spider’ veins are dilated capillary veins in the skin. They may be red, blue or purple. They may run in lines or be arranged in clusters. These veins may be flat or raised above the skin surface.

A solution is injected into the vein to ‘sclerose’ or scar the vein shut. The solution irritates the vein, causing the vein walls to become sticky. Over time, the vein seals shut and is reabsorbed back into the body.