- A contraindication to the use of either warfarin or aspirin e.g. active peptic ulcer disease, active bleeding diathesis, platelets < 100,000*, hematocrit < 30*, clotting factor abnormality that increases the risk of bleeding, alcohol or substance abuse, severe gait instability, cerebral hemorrhage, systemic hemorrhage within the past year, severe liver impairment (SGOT > 3x normal*, cirrhosis), allergy to aspirin or warfarin, uncontrolled severe hypertension (systolic pressure > 180 mm Hg or diastolic pressure > 115mm Hg), positive stool guaiac that is not attributable to hemorrhoids, creatinine > 3.0*