For the official dates and deadlines of the respective academic year please consult the circular of the specific year. Academic Year. The academic year begins on October 1st of a given year and ends on September 30th of the following year. Semester. If the tums in your medicine cabinet have expired, consider them bad and discard them as other medicines. Do unopened tums go bad? Yes, treat tums as a medication. Once the tums expiration date has passed, the tums should be discarded the same as you would discard any other expired medication. How long do tums last in the fridge? 9hdZl.