Sclerotherapy is a medical procedure designed to treat varicose veins and spider veins. During the treatment, a sclerosant solution is injected directly into the affected veins. This solution irritates the vein walls, causing them to collapse and eventually fade from view. Sclerotherapy is typically performed in a doctor's office and requires little downtime, making it a convenient option for many patients. Most individuals notice improvements within a few weeks, though full results may take several months to become evident.