How to Know If Your Alcohol Has Gone Bad

Contrary to common belief, even though it is a preservative, alcohol can go bad. While the turn doesn’t happen quickly for most booze—for many bottles it takes years—it does happen eventually. And those bottles we obsessively save for special occasions or just use a couple times a year are prime candidates. But while almost all alcohol can go bad given enough time and improper storage, it doesn’t all go bad in the same way. Here’s how to know if your bottle has turned.

Vermouth is an aromatized, fortified wine, the key word for our purposes being “wine.” And while it will last longer than regular wine, it can, like its Cabernet cousin, turn to vinegar. A vinegar flavor isn’t the only way to know if your vermouth has turned, though. Other changes to look for are a dulling of flavors (this can happen before any more pronounced off flavors completely take over) and a slightly brownish color in dry vermouth.

Cream liqueurs, like Irish cream, will start to smell a little like spoiled dairy when they begin to go bad. And if they aren’t sealed and kept in the fridge, they can even start to get chunky and coagulate.

Liqueurs like amari are generally pretty shelf stable and will last for a long time. But if you don’t finish an open bottle, it will eventually oxidize and turn. If it does, you may notice that the liquid inside gets thicker—that’s because previously unfermented sugars turn into glycerin. As those sugars break down, it may also become browner, like vermouth. And finally, you might notice sediment form on the bottom of the bottle.

First thing’s first: This really only applies to open bottles. If a bottle that’s 80 proof or higher remains unopened and stored at room temperature or below, it will stay good almost indefinitely. Just make sure you store it upright or the alcohol can eat away at the cork. But, while it is less likely, full proof spirits can go bad. Once you open a bottle at home, you don’t want to keep it for much more than a year. If you have half a bottle left, you want to get through it in about eight months. If you have a quarter bottle, try to finish it in three to four months. If you don’t finish in time, the liquid that is left can oxidize. If that happens, the taste will become duller and, in some cases, slightly sweeter. Let this be a lesson to not hoard your open bottles. Have a party. It’s for your own good.