Moed and colleagues present a comprehensive review of cantharidin. They delineate the historical and folk uses of cantharidin as well as governmental regulatory issues. Although cantharidin lost Food and Drug Administration approval in 1962, it has been proposed for inclusion in the “Bulk Substances List” and may be obtained through compounding pharmacies or proprietary sources. The authors outline the mechanism of action of cantharidin and its dermatologic applications. Although topical treatment with cantharidin rarely results in scarring or systemic intoxication, they note that deaths due to ingestion have been reported. The authors also review the symptoms of and treatment for systemic cantharidin poisoning. With this article, Moed and coauthors offer reassurance that proper in-office application of topical cantharidin remains a safe and valuable therapeutic option for warts and molluscum.