Complication of warfarin (360/1700)

A 72 yo man has been on warfarin for 2yrs because of past TIA and stroke. What is the most
important complication that we should be careful with?
a. Headache
b. Osteoporosis
c. Ear infection
d. Limb ischemia
e. Diarrhea

answer A for fear of subdural hemorrhage