Medical treatments carry unique benefits and risks which patients must understand in order to decide which of their options is best for them. Prior research has demonstrated that patients are ill-equipped to understand both medical terminology and the statistical information presented to them through standard decision aids. Patients are unable to use the information about treatments to make decisions and as a result make poor choices with regards to their healthcare. The contributions of this work are 1) a multi-dimensional model for describing the content of decision aids; 2) TreatmentExplorer, a prototype interactive decision aid designed to communicate treatment risks and benefits through the use of visualization, animation, and guided narration; 3) an evaluation of TreatmentExplorer with four experts in health communication; 4) a preliminary usability evaluation comparing the performance of TreatmentExplorer against design alternatives, and 5) guidelines for interactive decision aids based on the results of these preliminary user evaluations.