Sodium tetradecyl sulfate is an anionic surfactant which occurs as a white, waxy solid. Sodium tetradecyl sulfate is the active component of the sclerosant drug Sotradecol. Sotradecol (sodium tetradecyl sulfate injection) is a sclerosing agent. Intravenous injection causes intima inflammation and thrombus formation. This usually occludes the injected vein. Subsequent formation of fibrous tissue results in partial or complete vein obliteration that may or may not be permanent. Sotradecol® (sodium tetradecyl sulfate injection) is indicated in the treatment of small uncomplicated varicose veins of the lower extremities that show simple dilation with competent valves. The benefit-to-risk ratio should be considered in selected patients who are great surgical risks. Sodium tetradecyl sulfate is a potent toxin for endothelial cells in that brief exposure to even low concentrations are effective in stripping endothelium over a considerable distance and exposing highly thrombogenic endothelium in the process. Diluted sodium tetradecyl sulfate is also able to induce a hypercoagulable state, possibly by selective inhibition of protein C, and can also promote platelet aggregation. 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%