Sclerotherapy is treatment of spider veins mostly on the legs. It is a technique in which a very fine needle is used to inject a solution such as Sotradecol or Asclera, directly into the blood vessel. The solution causes an inflammation of the cells that line the vein. In response, the veins close up and collapse, no longer visible on the surface of the skin. The procedure itself takes just a few minutes and the veins disappear in 4 to 6 weeks. People resume normal activities immediately and can lead to success rate over 90-percent.