Does penicillin have an expiration from date issued?
Yes it does, not sure exactly how long it takes to expire, but I do know that it definitely does have an expiration date.
All penicillin will go bad after a period of time, but it is actually better to keep liquid penicillin refrigerated. It is a good idea to check the expiration date on your penicillin, and dispose of it when it expires. Penicillin that has gone bad will not help you, and you should be careful with medications that are past their date.
It depends. It does decompose, like all organic compounds, but not suddenly on the expiration date. If you're a few days or a month over, go for it if you're a year over ... it's time to trash it and buy a new bottle. As a general rule, the more "organic" the compound, the worse the stuff gets post expiration (aspirin lasts longer than penicillin)