Sclerotherapy is a minimally invasive procedure done by your healthcare provider to treat uncomplicated spider veins and uncomplicated reticular veins. Sclerotherapy involves injecting a solution directly into the vein. The sclerotherapy solution causes the vein to scar, forcing blood to reroute through healthier veins. The collapsed vein is reabsorbed into local tissue and eventually fades. Sclerotherapy is considered the treatment of choice for spider leg veins. The treatment is minimally invasive. The procedure also can improve related symptoms such as aching, swelling, burning and night cramps. Treated veins tend to fade within a few weeks, although occasionally it may take up to two months to see the full results. In some instances, several sclerotherapy treatments may be needed.