SN instructed patient / caregiver regarding medication Coumadin / Warfarin. SN explained to patient / caregiver that Coumadin / Warfarin is an anticoagulant which is prescribed to people with an increased tendency for thrombosis or as secondary prophylaxis ( prevention of further episodes ) in those individuals that have already formed a blood clot ( thrombus ). Explained that Warfarin treatment can help prevent formation of future blood clots and help reduce the risk of embolism. Informed that Warfarin will prolong bleeding time, instructed to avoid activities that increase risks of trauma. SN explained to patient / caregiver that the adverse effects of this medication includes: hemorrhage, nosebleeds and blood in urine or stool ( black tarry stools ). Instructed to notify physician if experiencing unusual bleeding while on this medication.