How to tell when yogurt is bad?

In this brief article, we are going to answer the question “how to tell when yogurt is bad” with an in-depth analysis of different ways to spot bad yogurt. Moreover, we are going to discuss the health implications of eating bad yogurt and whether or not you can consume the yogurt that is past its best-by date.

How to tell when yogurt is bad?

If you are not sure whether your yogurt has gone bad or not, here you can find five different signs that will help you to determine if your yogurt may have been spoiled:

Important: eating yogurt that has passed its prime increases the risk of getting a serious foodborne disease (1-5). So, you should not eat spoiled yogurt!

  • Mold Growth: Check the surface of the yogurt for any visible mold or strange growth. Mold can appear as fuzzy patches, spots, or discoloration on the surface, and it is a clear indication that the yogurt has spoiled. 

Remember that molds produce dangerous mycotoxins that can make you very sick, so you should never eat yogurt contaminated with molds (6).

  • Off-putting Odor: you should always smell your yogurt before consuming it. If it has a strong, sour, or unpleasant odor that is different from its usual smell, it is likely spoiled. 

A foul smell can be an indication of bacterial growth or fermentation gone wrong.

  • Separation or Watery Texture: Fresh yogurt typically has a creamy and smooth consistency. If you notice excessive liquid separation, a curdled appearance, or a watery texture, it could be a sign of spoilage. 

This separation may occur due to the breakdown of proteins and the growth of unwanted bacteria.

  • Unusual Texture or Color: Check the texture of the yogurt. If it feels excessively lumpy, grainy, or slimy, it is a warning sign. 

Similarly, if the color appears significantly different from its normal shade, such as grayish or pinkish hues, it may indicate spoilage.

If you observe any of these signs, it is best to discard the yogurt to avoid the risk of foodborne illnesses. Remember that your safety comes first!

Can you get sick from eating spoiled yogurt?

Yes, eating spoiled yogurt can pose health risks due to the presence of harmful pathogens (1-5). 

Here are some examples of pathogens that can cause foodborne illnesses and the associated symptoms:

  • Salmonella: This bacteria can cause salmonellosis, resulting in symptoms such as diarrhea, abdominal cramps, fever, and vomiting (4). 

While yogurt is not a common source of Salmonella contamination, if the yogurt was contaminated during production or storage, it could lead to illness if consumed.

  • Certain strains of E. coli: E. coli strains like E. coli O157:H7, can cause severe food poisoning. Symptoms may include diarrhea (often bloody), abdominal pain, nausea, and vomiting (3). 

While yogurt is not a typical source of E. coli contamination, cross-contamination during handling or improper sanitation could lead to its presence.

  • Listeria monocytogenes: Listeria contamination is a serious concern, especially for vulnerable populations such as pregnant women, newborns, elderly individuals, and those with weakened immune systems (2). 

Listeriosis symptoms can include fever, muscle aches, nausea, diarrhea, and in severe cases, it can lead to meningitis or bloodstream infections. If the yogurt has been contaminated with Listeria, it can pose a risk.

  • Staphylococcus aureus: Staphylococcus aureus is a common bacteria that can cause food poisoning when its toxins are present in food (1). 

Symptoms may include rapid onset of nausea, vomiting, stomach cramps, and diarrhea. If the yogurt has been contaminated with Staphylococcus aureus and its toxins, it can lead to illness if consumed.

It is important to note that the likelihood of encountering harmful pathogens in commercially produced yogurt that is within its shelf life and stored properly is generally low. 

However, if the yogurt is already spoiled, has an off smell or taste, or exhibits signs of contamination, it is highly recommended to avoid consuming it to minimize the risk of foodborne illnesses.

What should you do if you suspect you have eaten spoiled yogurt?

If you have consumed spoiled yogurt and suspect it may have made you sick, you should firstly assess your symptoms. Look out for signs of foodborne illness such as nausea, vomiting, diarrhea, abdominal pain, fever, or discomfort (7). 

It is also important to stay hydrated by drinking plenty of fluids like water or oral rehydration solutions, especially if you experience vomiting or diarrhea (8). 

It is also very important that you rest and monitor your condition, as most symptoms of foodborne illnesses tend to resolve within a few days. 

However, if symptoms worsen, persist, or become severe (e.g., high fever, bloody diarrhea), it is essential to consult a healthcare professional for guidance and treatment. 

If you suspect the spoiled yogurt caused your illness, consider reporting the incident to local health authorities or food safety agencies to ensure public safety.

Remember that it is always best to consult with a healthcare professional if you have specific health concerns or questions. They can provide personalized guidance based on your situation and help ensure appropriate care.

Is yogurt safe to use after the best-before date?

The “best by” or “best before” date that is written on the pack of yogurt refers to the quality rather than safety so the yogurt does not necessarily go bad immediately after the best before date.

This date refers to the time during which you can enjoy the peak quality and flavor of yogurt but you can still use yogurt that is past this date as long as it was stored properly, there is no leakage in the pack and no signs of spoilage are present.

If the yogurt has been stored in the refrigerator at the recommended temperature and has not been opened for an extended period, it may still be safe for consumption. 

On the other hand, if the yogurt has been stored at room temperature, exposed to fluctuating temperatures, or has been opened for an extended period, the risk of spoilage increases, and it’s advisable to exercise caution.

Consequently, iit is very important to use your judgment and consider other factors such as the storage conditions and the length of time beyond the best-before date.

It’s always a good idea to rely on your senses and evaluate the product before consuming it. If you notice any unusual changes in smell, appearance, or taste, it is always  best to discard the yogurt to avoid the risk of foodborne illnesses.


In this brief guide, we answered the question “how to tell when yogurt is bad” with an in-depth analysis of different ways to spot bad yogurt. Moreover, we discussed the health implications of eating bad yogurt and whether or not you can consume the yogurt that is past its best-by date.


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