How Drug Expiration Dates Work (Video) (IMAGE) American Chemical Society Caption We've all seen the expiration dates on prescription and over-the-counter medications. What's less obvious to us as consumers is how these dates are determined and to what extent medicines actually go bad. In this video, Reactions explains where drug expiration dates come from: https://youtu.be/aT4qzgEQr-Y. Credit The American Chemical Society Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.