Warfarin is widely used in clinical practice all over the world. We report a man in whom prominent eosinophilia appeared after the initiation of warfarin administration following aortic valve replacement. Laboratory data following the administration and discontinuation of warfarin suggested that this drug was responsible for the eosinophilia. It is important to recognize the possibility of warfarin-induced hypereosinophilia as a latent adverse effect even when there are no clinical signs or symptoms.
2012 by The Japanese Society of Internal Medicine