Interesting question. For 2 reasons - 1. Not sure why a licensed physician in our very litiginous society would injected anything whose shelf life has expired. The flip side is 2. A product that is already in one's system may last way longer than it's expiration date. So, why are we so hung up on expiration date?well, reason being, it's medically deemed safe. And, if for any reason, patient suffers an unintended consequence, he/ she may be protected under the law. On the other hand, a physician knowingly using expired products may be liable.I've always believed that one should be particularly careful about having any substances injected into his/ her system. Because, no one should be taking chances with his/ her health trying to save a few bucks. As a physician, it's our principle, 'first do no harm.'My suggestion - do not compromise when it comes to your health. Best.