Sclerotherapy involves the injection of a sclerosing agent into superficial veins of the leg. In response to this the vein collapses and is reabsorbed by the body. The response to treatment is dependent on the size of the spider veins (diameter of the vein), and the surface area required for treatment. It is not unusual for patients to require multiple treatments. Compression stockings need to be worn for several weeks after this procedure. Consequently, this procedure is best done during the cooler months of fall, winter, and early spring.