Ginkgo biloba is a widely used herbal product that could potentially have a severe interaction with warfarin, which
is the most frequently prescribed anticoagulant agent in North America. Literature, however, provides conflicting
evidence on the presence and severity of the interaction. In this study, we developed text processing methods to
extract the ginkgo usage and combined it with prescription data on warfarin from a very large clinical data
respository. Our statistical analysis suggests that taking concurrently with warfarin, gingko does significantly
increase patients’ risk of a bleeding adverse event (hazard ratio = 1.38, 95%CI: 1.20 to 1.58, p