Injection sclerotherapy is used to treat spider veins and sometimes small varicose veins. The vein is injected with a sclerosing agent using a very fine needle. This chemical compound causes the blood vessel to close up and eventually disappear. The procedure is virtually painless, and most patients report feeling only a slight tingling or burning sensation. While sclerotherapy does not provide a complete elimination of the problem veins, the majority of patients experience very good results. Some patients do report poor results, and in rare cases the patient’s condition has worsened after treatment. If the vein is not located near the surface of the leg, it may be necessary to use Ultrasound Guided Injection Sclerotherapy.