Ginger-associated overanticoagulation by phenprocoumon.

Objective: To report a case of ginger-phenprocoumon interaction resulting in an elevated international normalized ratio (INR) and epistaxis.

Case Summary: A 76-year-old white European woman on long-term phenprocoumon therapy with an INR within the therapeutic range began using ginger products. Several weeks later, she developed an elevated INR up to 10 and epistaxis. The INR returned to the normal range after ginger was stopped and vitamin K1 was given.

Discussion: There have been a number of investigations resulting in conflicting opinions on the effect of ginger on hemostasis, specifically, platelet inhibition. Nevertheless, based on these investigations, recommendations have been issued to refrain from ingesting ginger and other herbals like garlic or ginkgo biloba in situations where bleeding may be critical. An objective causality assessment revealed that the adverse drug event as a result of the phenprocoumon and ginger interaction was probable.

Conclusions: As of writing, this was the first case report that may support an interaction between an oral anticoagulant and ginger together with a brief review of the literature on ginger and hemostasis. As this interaction was observed only by chance, this case highlights the importance of self-control of anticoagulation with coumarins particularly for the detection of unknown interactions.