High Quality Content by WIKIPEDIA articles! Sodium tetradecyl sulfate (STS) is a sclerosant drug. It is commonly used in the treatment of varicose and spider veins of the leg, during the procedure of sclerotherapy. Being a detergent-based chemical, its action is on the lipid molecules in the cells of the vein wall, causing destruction of the internal lining of the vein and eventual sclerosis of the vein. It is used in concentrations ranging from 0.1% to 3% for this purpose. In the UK, Ireland, Italy, Australia, New Zealand and South Africa, it is sold under the trade-name Fibro-Vein in concentrations of 0.2%, 0.5%, 1.0%, and 3%.