mayo left out overnight
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Mayo Left Out Overnight – Is It Still Good?

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Everyone likes to put condiments on their sandwiches and burgers!

Have you ever used your favorite condiment like mustard, mayonnaise, or maybe even something like ketchup and then forgot to put it back in the fridge? 

Maybe you walked out the next morning only to find that mayonnaise still sitting on the counter. Have you found yourself in this situation?

The next question becomes do you have to toss it out or can you toss it back into the fridge? Every condiment is different and some people wouldn’t risk it at all. 

So is mayo left out overnight still good? The truth is that it depends on just how long the overnight was. If the mayo was left out for 12+ hours, it probably needs to go in the trash. If it was closer to 8 or fewer hours, you might still be able to salvage it. 

In this guide, we are going to answer this question in full detail. We will talk about whether or not your mayo is still good after it has been sitting out or if it will make you sick.

We will also cover signs to know whether it is bad so you can know for sure whether or not that mayo is safe to eat. 

Keep reading to learn more about whether mayo left out overnight is good or not! 

What’s in Mayo? 

Understanding what is in mayonnaise will make a significant difference in helping you to truly know what could cause your mayo to go bad.

Most condiments would really probably be just fine after a night sitting on the counter but mayonnaise is a little something special. 

It’s the ingredients that are in mayo that make us a little bit more cautious when it comes to leaving it out.

This is specific to real mayonnaise which contains eggs as one of its primary ingredients. The FDA has a specific definition of what real mayonnaise is.


There are several different imitation mayonnaise options out there as well. You should be cautious about those but they are not the same as real mayonnaise. 

Real mayonnaise is made with raw egg yolks. When it comes to eggs as an ingredient, you have to be careful because there is the risk of salmonella poisoning if something isn’t handled properly with these ingredients. 

In fact, mayonnaise is almost solely eggs with the addition of some vinegar, lemon juice, and some salt. The vinegar and lemon juice help to keep the eggs from going bad in a sealed container. 

The official word from the FDA is that your mayonnaise shouldn’t be left at room temperature for more than 8 hours.

If it is hotter than room temperature, this length of time is significantly reduced as warm temperatures are a breeding ground for bacteria. 

The Catch

So here’s the deal. Your mayonnaise was definitely made with eggs. It was also made with things like vinegar or lemon juice.

You certainly don’t buy your mayonnaise from the refrigerated section in the grocery store so why would it matter if it sits out on the counter? 

Of course, if you are using homemade mayonnaise, it’s a whole different story

Here’s the thing. Store-bought mayonnaise is pasteurized and processed before it gets sealed and shipped out to buy from the store. The eggs are pasteurized so you have a little bit of leeway on timing. 

When it comes to raw eggs, the guidelines are that they can’t be out of the fridge for more than 2 hours and only about an hour in hot temperatures. But the thing is, you aren’t dealing with your average raw eggs here. 

mayo left out overnight

Remember that the eggs in mayonnaise are pasteurized and processed. This gives you some extra time when it comes down to it. 

When mayonnaise is sealed from the store, it doesn’t have to be in the fridge. When you pop the seal on that mayonnaise, that’s when you have to be more cautious about the times your mayo is left out. 

The good news is that you still have a much larger window than you would with homemade mayonnaise or raw eggs. The key word here is pasteurization. 

You will notice that your jar of mayonnaise does have instructions to refrigerate after opening.

If you happen to forget to put it back in the fridge, the best rule of thumb is that your mayonnaise will be fine for about 8 hours at room temperature. 

What Happens if You Eat the Mayo Left Out Overnight? 

In most cases, eating bad mayonnaise will not be life-threatening but it certainly will not be a great experience either. When you eat mayonnaise that is bad, you are likely to get food poisoning from doing so. 

Eating bad mayonnaise could leave you with the nasty side effects of food poisoning or salmonella. Neither of these are fun experiences so it is best not to risk it if you do suspect that your mayonnaise could be bad. 

Signs That Mayonnaise Has Gone Bad

The best thing that you can do is be familiar with the signs that mayonnaise has potentially gone bad. Remember that the FDA has pretty much given you an 8-hour window of time when it comes to mayo left out overnight

However, it’s still a good idea to know the signs that mayonnaise is no longer good so you can make an educated judgment call. It might be better not to take the chance in some cases.

The eggs can attract and grow bacteria and it may not always last for 8 hours so this is something to be aware of

Mayonnaise should be stored in the fridge after it was been opened and when you accidentally leave it out, know the signs as a backup. 

There are signs that will help you notice if the mayonnaise has potentially gone bad. Here are a few of them:

  • Check for smells. If the mayonnaise smells putrid, sulfuric, or acrid, this is a sign that it has gone bad and you probably shouldn’t eat it. 
  • Do you notice an odd color such as white or yellow or even a hint of brown? These are often signs that your mayonnaise is going bad. 
  • If you notice anything like mold or mold spores, your mayonnaise needs to be thrown out. 
  • You can taste a small sample of the mayonnaise. If it is at all off in flavor, you need to go ahead and throw it out. Do not eat anymore. 

Some experts also mention that if you notice a lot of separation in your mayonnaise, this could be a sign that it needs to be tossed out.

A little bit of separation is normal as the oil can settle. Stir it up and evaluate the smell and appearance after you’ve stirred it in this case

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