The potential for interactions with current medications should always be considered when administering or prescribing any drug. Considering the staggering number of drugs patients may be taking, this task can be daunting. Fortunately, drug classes employed in dental practice are relatively few in number and therapy is generally brief in duration. While this reduces the volume of potential interactions, there are still a significant number to be considered. This article will review basic principles of drug interactions and highlight those of greatest concern in dental practice.