Coumadin is a medication commonly used as an anticoagulant, which means it helps prevent blood clots from forming. It works by inhibiting the action of vitamin K, a nutrient essential for blood clotting. Patients may be prescribed Coumadin to reduce the risk of stroke, heart attack, or other serious conditions related to blood clots. While taking Coumadin, regular blood tests are necessary to monitor its effectiveness and ensure the dosage is appropriate. Patients must also be cautious about their diet, as certain foods high in vitamin K can affect how the medication works.