Warfarin sodium can cause major or fatal bleeding. Bleeding is more likely to occur during the starting period and with a higher dose (resulting in a higher INR). Risk factors for bleeding include high intensity of anticoagulation (INR 4.0), age 65, highly variable INRs, history of gastrointestinal bleeding, hypertension, cerebrovascular disease, serious heart disease, anemia, malignancy, trauma, renal insufficiency, concomitant drugs (see PRECAUTIONS), and long duration of warfarin therapy. Regular monitoring of INR should be performed on all treated patients. Those at high risk of bleeding may benefit from more frequent INR monitoring, careful dose adjustment to desired INR, and a shorter duration of therapy. Patients should be instructed about prevention measures to minimize risk of bleeding and to report immediately to physicians signs and symptoms of bleeding (see PRECAUTIONS: Information for Patients). What are the possible side effects of Coumadin? • Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat. • Call your doctor at once if you have any of these serious side effects: · skin changes or discoloration anywhere on your body; · purple toes or fingers; · pain in your stomach, back, or sides; · severe dizziness, headache, or weakness; · diarrhea; · easy bruising or bleeding that will not stop · blood in your urine; · black, bloody, or tarry stools; · coughing up blood; · nosebleeds or bleeding gums; · urinating less than usual; · sudden headache, confusion, problems with vision, speech, or balance; · sudden leg or foot pain; or · sudden numbness or weakness, especially on one side of the body. • Other less serious side effects are more likely to occur, such as: · excessive gas or bloating; · diarrhea, nausea, or vomiting; · hair loss; or · loss of appetite, weight loss. • Side effects other than those listed here may also occur. Talk to your doctor about any side effect that seems unusual or that is especially bothersome.