Soda, like other beverages, has ingredients in it that spoil in time, so the expiration dates help consumers know how long a soda will remain safe to drink. Generally, sealed sodas last from 6 to 9 months past their expiration dates, whether stored in the refrigerator or in the pantry.
Opened bottles and cans of soda last only a few days after opening. In a pantry an open can of soda is only good to drink for 1 day and an opened bottle of soda should be consumed within 1 day. In the refrigerator, an open can must be consumed within 1 day, but an open bottle will be good for 2 to 5 days after it is opened.
It may be difficult to tell when a soda is not safe to drink. The first sign that a soda is old is when the carbonation begins to disappear. Although this does not mean the soda is bad, it does mean it is past its prime and will taste flat. Determining if a diet soda is bad is a little easier. The farther away it is from its best by date, the worse it will taste. Artificial sweeteners break down differently than sugar, making the soda taste bad.