Prescription drug laws are ALL federal. It wouldn't do that much good to carry a written prescritpion with you, because it would expire in 6 months whether or not it had been filled. To be perfectly safe from a legal standpoint, keep whatever you are going to keep in the original container, which was small since a dentist wrote the order; it couldn't have been for more than 8-12 tablets. The earlier post about the fact that the pharmacist can tell what the expiration date is is correct is you contact him/her while he/she is still using the same open bottle. That expiration date is on the container. As a practical matter though, I would take those tablets 20 years from now. The only thing that might happen is a reduction in potency of the codeine. Now, tylenol (acetaminophen) taken in large doses is toxic to the liver, and arguably could be if it degraded into something else over a couple of decades as in my example above. But this is not going to cause a significant health hazard with four tablets to relieve joint pain over a 24hour period, as you would be using it. By the way, should you decide to take the tablets out of the original container and put them in something else, I would just say they were acetaminophen tablets unless they were embossed with the '3'. If someone had the nerve to ask, I would have the nerve to tell them whatever I wanted them to know.