Soft drink cans or bottles often carry a printed date. If you've discovered an older drink that's past this date, you may be wondering about whether you can still drink it. Although several factors can influence this decision, the answer is usually yes: This is a "best-before" date rather than an expiration date. Sealed soft drinks usually retain their quality for months after this date.
Soft drinks may not go bad in the same way that a loaf of bread or a package of hot dogs can, but that doesn't mean that they retain their quality forever. Over time, a soft drink can lose its carbonation. Additionally, its flavor can break down.
The simplest way to minimize the loss of carbonation from soft drinks is to keep them cold. As the drink heats, the liquid's ability to absorb CO2 decreases, causing more gas to escape from the solution. As a result, chilled drinks retain their fizz longer -- and even unrefrigerated drinks will stay fresh longer if kept in a cool place.
There's no hard-and-fast rule for how long a bottle or can of pop will last after its best-before date. However, you should usually be able to keep a drink for at least three months if not longer after the date on the container as long as it's been stored properly. If in doubt, open the container and have a sniff or a sip; if the taste has changed or if the soda doesn't smell like you'd expect, it's probably time to throw it out.