I have had a bottle of Xanax that my doctor prescribed me that has sat on a shelf for two years. I only have to take it every once in a while, and I'd rather not fill it again unless I have to. How long will it stay good?
According to experts, most prescriptions are still potent long past their expiration date - which is typically 2 to 3 years. It may be somewhat less potent or it could just as potent as it ever was. The expiration date does not indicate that a drug is no longer good - it simply indicates a date at which a drug manufacturer guarantees that it is good. A large Air Force study in conjunction with the FDA concluded that most drugs are good long past their expiration dates and they use them past their expiration dates.
If your Xanax has been properly stored in a temperature controlled room since you filled the prescription, and if it is in its own bottle (not mixed with other medications) it's probably still fine. If in doubt you can always call your pharmacist to see what they would advise.
You can store medications that are in tablet or capsule form in the freezer, thereby extending their life indefinitely. For more information about freezing your meds, read this article.