Sclerotherapy is one of the most common procedures used to treat spider veins. A solution containing a substance like saline, or polidocanol is injected into the affected veins. The solution causes the veins to collapse, sealing them shut. Sclerotherapy is a non-invasive procedure that’s done in a doctor’s office. You’ll likely have a few small bruises after the treatment, but they’ll go away within a few weeks. Sclerotherapy is best for veins that are close to the surface of the skin. With sclerotherapy, you can expect your veins to disappear completely in about three-quarters of patients, while they improve in the other quarter of patients.