Definition 

Sclerotherapy is the most commonly used treatment for small diameter (<5mm) veins, such as spider veins.  In Sclerotherapy, a liquid is injected with a tiny needle into the vein that causes inflammation of the vein wallsand causes the vein walls to stick to one another, collapsing the walls together. This solution and the use of a compressionm stocking, effectively prevents the vein from working and it stops carrying blood. The vein therefore disappears with time.

Small veins are effectively removed by Sclerotherapy but veins will often reappear if the underlying causes, incompetent blood vessels, are not treated. Sclerotherapy is associated with brown discoloration of the vein that may take up to one year to disappear and usually requires repeated treatments. It rarely can cause skin ulcers and as with all medications, some patients may have an allergy to the solution.