Interact is the largest computerized database of drug-drug interactions and references devoted to psychotropic drugs. An intuitive interface allows the program user to quickly create a list of up to 20 drugs and to search for clinically relevant drug interactions between the ssychotropic drugs and all others on the list, whether psychotropic or not. All interactions are described, their mechanisms (if knows) explained, and they are rated on their potential severity and how well-documented the interaction is thought to be. Specific supporting scientific literature is referenced, and explanatory notes are provided for many of the better-studied types of interactions with additional bibliographic citations.