Foam sclerotherapys a procedure that involves injecting “foamed sclerosant drugs” within a blood vessel using a syringe. Foam is created by mixing of sclerosant (Sodium Tetradecyl Sulfate or polidocanol) with air or a physiological gas like carbon dioxide in a syringe . This increases the surface area of the drug. The foam sclerosant drug is more effective than the liquid one in causing sclerosis for it does not mix with the blood in the vessel and in fact displaces it, thus avoids the dilution of the drug and causing maximal sclerosant action. It is therefore useful for longer and larger veins.