Expiration date is on your pharmacist's bottle. Most meds are good for 2-3 years but you don't know how old it was when you got it. Play it safe and discard it. Also technically in the US (dunno aboot canada) tylenol with codeine is controlled substance. If by any chance you got cought with it without prescription (as in putting it in plain bottle in your psk) you will be in trouble if someone wanted to be stupid about it.