Hello, I assume you re talking about deep vein thrombosis. The usual treatment starts with a low molecular weight heparin like enoxaparin (lovenox) and continues with a coumarin-drug which raises INR to protective levels. Blood thinners help to stop ongoing thrombosis but they don t affect the already formed clots. This is very important because an expanding clot can detach from the vessel wall and occlude pulmonary vessels causing life threatening conditions. With time, the body will absorb the clot and sometimes the vein can become patent again although not as functional as before the thrombosis. I hope I ve helped you understand your condition better! If you d like more information, please let me know and I ll be glad to answer. Kind Regards!