I'm a retired neurosurgical anesthesiologist with 37 years of experience. Medications one day after their so-called expiration dates are just as effective as they were 24 hours earlier. Loss of potency and therapeutic efficacy over time varies tremendously depending on storage conditions: drugs kept refrigerated and in the dark will likely work just fine for YEARS after their expiration date. Pharmaceutical companies have noted that they are extremely conservative when it comes to expiration dates, much preferring to err on the side of caution. Dept. of eating your own dogfood: I had an anaphylactic/allergic reaction of unknown etiology in late 2015, my first ever; I had to go to the ER for IV steroids and Benadryl for treatment. No recurrence since. I immediately bought two Epi-Pens, one for my house and one for my car. Their expiration date was March 2017. I am completely comfortable not having purchased new ones, especially considering their now inflated prices even after all the bad publicity that focused on their markup. So I have bet my life on my belief that these "expired" epinephrine injectors will save my life should I ever have another anaphylactic/allergic reaction. However — if someone asked me for advice, I would tell them to get up-to-date ones; as a former practicing physician, this is one of those cases where what you advise is quite different from what you yourself would do.