Recommended treatment is warfarin for 3–6 months to reduce recurrence after a first DVT episode. In patients treated with intravenous heparin and then with warfarin for 3 months, continuation of warfarin for 2 years may more effectively reduce recurrence. However, after 2 years recurrence rates may be the same.

Extending the duration of oral anticoagulant indefinitely decreases recurrence compared with 6 months of therapy. However, this long-term therapy results in a higher incidence of major bleeding. Longer anticoagulant therapy is recommended for patients who are bedridden or immobilized or who have heart failure, cancer, antiphospholipid antibody syndrome, or factor V Leiden (clotting) defect or some other defects in clotting ability.

Bleeding is a major side effect of oral anticoagulants, usually due to surgery, trauma, peptic ulcers, or cancer. Serious bleeding may occur if the warfarin dosage is too high. A lowered dosage of warfarin generally reduces risk of bleeding.

Coumadin-induced skin necrosis (destruction of skin tissue).This is rare and usually occurs between 3 and 10 days after therapy is started. It most often involves the abdomen, buttocks, thighs, and breasts. When this happens, anticoagulant therapy is immediately stopped.