thanks to Yarnell/Abascal: herbalists

Any herbs that interfere with platelet
function, such as Allium sativum (garlic)
bulb, Ginkgo biloba (ginkgo) leaf, or Asian
ginseng, could theoretically potentiate
warfarin. In fact, there have been isolated
case reports with claims that garlic and
ginkgo each potentiate warfarin.13,14 No
changes in INR should be expected being
that these agents do not affect the clotting
cascade, only platelets. The risk of combining warfarin with any antiplatelet drug or herb is largely theoretical but is
still worth considering and being cautious.