Potential interaction of Ginkgo biloba leaf with antiplatelet or anticoagulant drugs: what is the evidence?

Some writers hold the view that the combination of Ginkgo biloba with anticoagulant or antiplatelet drugs represents a serious health risk. Such concerns are largely based on the assumption that Ginkgo has clinically relevant antiplatelet activity, as well as accounts of bleeding episodes associated with Ginkgo consumption. To investigate whether these bleeding episodes have a pharmacodynamic, idiosyncratic or coincidental basis, a review of controlled clinical studies and case reports was undertaken. Results from controlled studies consistently indicate that Ginkgo does not significantly impact haemostasis nor adversely affect the safety of coadministered aspirin or warfarin. Most of these studies were undertaken using EGb 761, a well-defined extract of Ginkgo biloba. In contrast, EGb 761 has not generally been implicated in the case reports. In general, the quality of these case reports is low. Nevertheless, the possibility of an idiosyncratic bleeding event due to Ginkgo use cannot be excluded on the basis of the available information. However, there is scant information from case reports or controlled trials to support the suggestion that Ginkgo potentiates the effects of anticoagulant or antiplatelet drugs. Such high-level safety concerns for this herb are deemed to be unsupported by the currently available evidence.