Asclera is a trade name for the sclerotherapy drug polidocanol.  While the name Asclera has been on the market for only a few years, polidocanol has been used around the world for a few decades.  Asclera is used primarily to treat spider veins.  The technique is called sclerotherapy.  Using a tiny needle, the medication is injected into spider veins (and sometimes small reticular veins and varicose veins).  The medicine causes the inner lining of the vein to get damaged, and the vein closes down.  The body then slowly absorbs the vein and it fades away.  It is quite safe.