Even though your clot has disappeared, you are at an increased risk for having another clot. Treatment with Coumadin (warfarin) helps to lower that risk and prevent another clot. The typical length of treatment with Coumadin for a blood clot in the leg is 3 to 6 months. If you have higher risk of developing a clot, the length of treatment may be longer. Since every patient is different, your doctor is the best person to answer how long you will need to continue Coumadin.