Question: I have been diagnosed with a blood clot in my leg and have been on blood thinners for two weeks. How long does it normally take for a blood clot to dissolve?

Dr. Hibberd's answer:
Deep vein thrombosis (DVT, also called venous thrombosis) is a blood clot that develops in a vein deep in the body. The clot may partially or completely block blood flow through the vein. Most DVTs occur in the lower leg, thigh or pelvis, though they can occur in other parts of the body as well.
Blood thinners (anticoagulants) decrease your blood’s ability to clot. They are used to stop clots from getting bigger and to prevent a blood clot from moving, but they do not break up blood clots that have already formed. Your body’s natural system may help dissolve the clot. In some cases, however, the clot will not completely dissolve. Warfarin (Coumadin) is a pill while heparin or low-molecular-weight heparin, including enoxaparin sodium (Lovenox) Fragmin (dalteparin sodium), and fondaparinux sodium (Arixtra) are injections. Heparin (or low-molecular-weight heparin), fondaparinux and warfarin may be given at the same time. Heparin and fondaparinux will act quickly, while the warfarin will take 4 to 5 days before it starts to work. Once the warfarin is working, the other anticoagulants will be stopped, but usually only after a minimum of 4 to 5 days of combined therapy.
Treatment for DVT with anticoagulants usually lasts for 3 to 6 months. The most common side effect of anticoagulants is bleeding. You should call your doctor right away if you are taking warfarin, heparin, low-molecular-weight heparin, or fondaparinux and experience easy bruising or bleeding.