Sclerotherapy is a minimally invasive injection procedure used to eliminate small varicose veins and spider veins. This treatment technique injects a saline solution directly into damaged veins, causing them to swell and stick together. Several weeks after the injection, the patient’s treated veins will collapse and become reabsorbed by nearby tissue, forcing blood to reroute to healthier veins. After sclerotherapy, patients may notice a significant improvement in the appearance and function of their treated veins. Several sclerotherapy treatments may be needed for severe cases of spider and varicose veins.