Sclerotherapy treatments are simple quick outpatient procedures. Most treatments take between fifteen and forty five minutes. As the procedure is almost painless, anesthesia is not typically required. During sclerotherapy, a chemical solution known as a sclerosing agent is injected at several points along spider veins. Sclerotherapy is commonly performed with a concentrated saline solution, although other chemical solutions or special foam may be used as well. The agent irritates the lining of the veins, which in combination with compression after treatment causes the vein walls to collapse. Over time, the veins will be absorbed by the body, restoring a smoother, more youthful appearance. Like other vein removal therapy, multiple treatments are usually required to achieve the desired results, but sclerotherapy can reduce the appearance of most spider veins and some small varicose veins significantly.