http://scopeblog.stanford.edu/2012/10/08/study-expiration-dates-have-nothing-to-do-with-shelf-life-of-drugs/ Even years after the expiration date, potency not compromised.. according to the Stanford study. Pill makers are required by statute to put an expiration date on prescribed meds. They will not "guarantee" potency after that date. They are happy to comply with the statutes. Not scientific logic. No money in logic.