Does Yogurt Go Bad? Because That Tub in the Fridge Has Been in There for Like Two Weeks

Creamy, tangy and sometimes sweet, yogurt is the refrigerator staple we reach for on the regular. Delicious as a quick snack, the foundation for a healthy breakfast, a cooling condiment for spicy and savory dishes (like this scrumptious couscous) and even in some of our favorite creamy desserts, yogurt might just be the most versatile ingredient in our fridge. But what sets yogurt apart is that it’s also really good for you: This protein-packed dairy product is rich with nutrients, and it contains strains of bacteria and yeast (i.e., probiotics) that promote digestive health. So yeah, we’re pretty big fans of the stuff. That said, we sometimes buy more yogurt than we can finish in a week. So what we really want to know is: Does yogurt go bad? Spoiler: The answer to that question is yes, but there’s more to it than that. Read on for everything you need to know about yogurt and food safety so you can make the most of the delicious dairy you’ve got in the fridge. 

Fellow yogurt-lovers, we’re sorry, but here it is again: Yogurt does indeed go bad and if you eat bad yogurt, it’s bad news (more on that later). You might be wondering how something that comes to you full of bacteria and yeast can spoil. The thing is that yogurt is packed with good bacteria, but that doesn’t make it magically resistant to growing the bad kind, too. Like any dairy product, certain conditions (particularly warm temperatures) encourage the development of bad bacteria. Also, yogurt that has been opened will spoil faster than an unopened container and according to USDairy.com, “bacteria...may grow more readily in yogurts with added sugar and fruit.” So what happens when you let your yogurt overstay its welcome in the fridge (or worse, never give it an adequately frigid place to call home)? Basically, you’re opening the door for “molds, yeast, and slow-growing bacteria to grow and spoil your yogurt.” Yuck. But never fear friends: For an all gain, no pain tango with your favorite tangy dairy product, just make sure you store it properly and give it a once-over before you dig in.

For optimal freshness and shelf life, yogurt requires prompt refrigeration at a temperature of 40 degrees Fahrenheit or less. (Hint: If your fridge is warmer than that, something isn’t working right.) In other words, put that quart of creamy Greek goodness in the fridge as soon as you get home from the store and return it to its preferred chilly climate as soon as you’re done spooning it into a bowl at breakfast time. When stored in this way, the experts at USDairy.com and USDA and say that the shelf life of yogurt is seven to 14 days from the day you open it, regardless of the sell-by date.

Good question, surprising answer. By the USDA’s own admission, any date you see on the packaging of your food has precious little to do with safe consumption. (How did we not know this earlier?) Just to reiterate: Best-by, sell-by, freeze-by, and use-by dates have no bearing on food safety. (That’s why it’s also perfectly safe to eat chocolate, coffee and even spices past their best-by dates, FYI.) In fact, these dates are only intended to provide a vague timeline for “optimum quality” to both retailers and consumers—and they’re determined by manufacturers according to a mysterious, undisclosed equation that includes a variety of factors. Bottom line: Packaging dates should be taken with a grain of salt. 

Experts agree that packaging dates be damned, you have seven to 14 days to consume your opened container of yogurt. But what if your eyes were bigger than your stomach and you walked away from an unfinished bowl of the creamy stuff? Answer: You might be able to enjoy that dairy another day. Per the pros at USdairy.com, yogurt that has been left out can still be refrigerated for future enjoyment as long as it hasn’t lingered at room temperature for more than two hours (or one hour at a temperature of 90 degrees Fahrenheit and up). Just keep in mind that this countertop time will significantly reduce the shelf-life of your yogurt, so don’t expect to revisit those leftovers two weeks later—instead plan to make short work of that yogurt within a day or two.

If you think you’ve followed all the best practices for yogurt storage but still have a funny feeling about the quart in your fridge, just follow these inspection tips and you’ll be able to glean where it falls on the freshness spectrum.

• Check for liquid: More often than not, some water will collect on the surface of yogurt and that’s perfectly fine—just give it a stir and enjoy your snack. However, if you notice an unusual amount of liquid sitting on top of the creamy stuff, that might be a sign of spoilage so you’re better off taking a pass.
• Smell: Another way to tell if yogurt has gone bad is simply by giving it a good sniff. But know that this method isn’t foolproof when it comes to yogurt that’s right on the edge of spoilage, especially since one’s sense of smell varies greatly from person to person. However, much like spoiled milk, few would mistake the smell of a truly rancid yogurt.
• Curdling: If a once smooth and creamy quart of yogurt has emerged from the fridge with a little extra texture, it’s probably best to toss it. Curdling is a sign that the yogurt has seen better days.
• Mold: This one is a no-brainer, but if you see any evidence of mold—white, green or any color of growth—on your yogurt, (don’t) kiss it goodbye. Because of its water content, yogurt that has been sitting around too long in the fridge is prone to mold...and it will make you sick.

If your spoiled yogurt comes from an unopened container, then you’ll likely only suffer a little bit of an upset stomach, food safety specialist Benjamin Chapman, PhD, a professor at North Carolina State University, told Women’s Health. If you eat spoiled yogurt from an opened container, then you may have some painful stomach cramps and diarrhea (possibly nausea) shortly after ingestion. But in both of these instances, the yogurt will taste bad—meaning, you likely won’t even want to eat it in the first place. 

Note: If you’re feeling sick after eating unpasteurized (i.e., raw milk) yogurt, your symptoms will likely be more severe. Per the CDC, any yogurt made with unpasteurized milk might be contaminated with some pretty nasty germs—listeria, salmonella, campylobacter and E. Coli, to name a few. Seek medical attention if you’re experiencing symptoms of dehydration associated with foodborne illness.