Hypereosinophilia associated with echinacea use.

Echinacea, believed by herbal practitioners to enhance the immune system, is one of the most widely used herbal supplements in the United States. Like most herbal products, it lacks strict FDA regulation and more information is needed about its potential adverse reactions. Here, we report the case of a patient with eosinophilia of unclear etiology whose condition resolved after cessation of this supplement. We feel this likely represents an IgE-mediated allergic process to echinacea.