There is an expiration date for a reason! Drugs like everything have a shelf life, the older they are, the more inneffective they become. Get the prescription renewed, refill...
Yes- I have used exp nexium that is more than a year old... while not recommended because of course they will not say it will still work... it still does for the most part. It doesnt harm you either way. Might not help the heartburn... at which point you are no further behind than you were anyhow.