7 signs that your yogurt has spoiled

You're about to scoop some yogurt when you suddenly notice the expiration date on the container. Whether the yogurt is nearing its expiration or has already passed it, you probably want to ensure it's still safe to eat. But how can you be sure? In this article, we’ll walk you through all the signs that indicate your yogurt has gone bad, so you can enjoy it without worries (or toss it out if necessary). We will also explain what the expiration date on yogurt means and what happens if you consume spoiled yogurt.

There's too much liquid on the surface of the yogurt. A bit of whey separation is normal, so if you notice a thin layer of liquid on top of your yogurt, it's usually fine—you can simply stir it in (or pour the liquid off) before eating. However, if you see a pool of liquid or a thick layer, it’s likely that your yogurt has lost its quality.

• Don't throw it out just yet—check for other signs of spoilage.
• The type of yogurt doesn’t matter—whether it's regular yogurt, fat-free yogurt, or Greek yogurt, the signs of spoilage remain the same.

The texture of the yogurt is lumpy instead of smooth. Stir the yogurt with a spoon to check its consistency. If you notice clumps or a gelatinous, hard-to-stir texture, it’s past its prime and starting to spoil.

The yogurt has a sour, unpleasant, or strange smell. Hold the container near your nose and take a gentle sniff. Fresh yogurt should have a mild, pleasant smell or no noticeable scent. Spoiled yogurt will have a sour, rancid, or yeasty odor, or just an odd smell altogether.

• If you're unsure whether the yogurt smells strange, check for other signs of spoilage and discard it if needed.

There is mold or unusual color on the surface.

This may seem obvious, but it’s always worth a close look—sometimes the mold is very small! If you see any pink, gray, or fuzzy spots on the yogurt's surface, throw it away immediately. You definitely don’t want to eat mold—it could make you sick!

The yogurt tastes sour, rancid, or unusually off. We don’t recommend tasting it, but if you’ve already eaten a spoonful before realizing something was wrong, or you’ve smelled and observed the yogurt and felt it was fine, the taste will tell you right away—spoiled yogurt will have a sour, unpleasant taste.

• Eating a spoonful of spoiled yogurt isn’t likely to make you sick, so there’s no need to panic if you’ve accidentally consumed a bit.

The yogurt container is swollen or deformed. If the plastic yogurt container is dented, it may indicate that the yogurt has been exposed to heat or moisture, so it’s almost certain that it’s no longer good. If the seal is broken, you should definitely throw the yogurt out—it’s likely contaminated.

The yogurt has been left out for more than 2 hours. You might have accidentally left the yogurt on the table—this happens to all of us! If the yogurt has been out for less than 2 hours, put it back in the fridge. However, yogurt left out will have a shortened shelf life, so be sure to eat it sooner.

• It’s hard to know the exact expiration of yogurt left at room temperature, so make sure to check for other signs before eating it.
• The warmer the temperature, the faster the yogurt will spoil. For example, if yogurt has been left in a place over 32°C for more than an hour, toss it out.

Once opened, yogurt will stay fresh in the fridge for up to 7 days. Make sure to store opened yogurt in an airtight container to protect it from warmth and contaminants. Avoid eating yogurt that's been opened for more than a week—it will lose its flavor quickly and bacteria can grow rapidly. Even if it looks and smells fine, it’s best to discard it. Better safe than sorry!

Greek yogurt typically has a shelf life of 1-2 weeks when properly stored in the fridge. The storage, expiration, and spoilage signs for Greek yogurt are the same as for regular yogurt. According to the USDA, all types of yogurt maintain quality for 1-2 weeks if kept refrigerated at 4°C.

• Greek yogurt is essentially regular yogurt that has had its whey separated, giving it a thicker texture. This whey-separated yogurt is often called Greek yogurt, but it doesn’t actually originate from Greece.

You can safely eat unopened yogurt within 15 days of the 'best by' date on the package. The 'best by' or 'use by' date is not the same as an expiration date; it marks when the yogurt’s quality starts to decline. As long as the yogurt looks and smells normal, it’s safe to eat.

• Always store yogurt in the fridge at 4°C to prevent spoilage. You can also freeze yogurt for 1-2 months, though its texture may change.

You may experience food poisoning symptoms if you consume spoiled yogurt. Mild symptoms include stomach pain, nausea, and vomiting. Symptoms (which some people may not experience) typically begin a few hours after eating spoiled food.

• Your illness severity will depend on the type of bacteria you’re infected with, the amount of food consumed, and whether your immune system is weakened.
• Symptoms can last from a few hours to a few days. You don’t need medical help for mild symptoms. To recover quickly, rest and stay hydrated.
• Seek medical attention if you have severe symptoms such as:
  • Vomiting or blood in stool
  • Severe abdominal pain
  • Diarrhea lasting more than 3 days
  • Severe fatigue, dizziness, or lightheadedness
  • Blurred vision or muscle weakness