How To Tell If Mayo Is Bad? Plus Storing it The Correct Way

Mayonnaise is arguably one of the most popular condiments in the U.S. Approximately 277 million Americans reportedly used mayo or a mayonnaise-type dressing in 2020. The number is expected to reach a whopping 283 million in 2024!

And this immense popularity of mayonnaise can easily be boiled down to its versatility. Given its mild flavor, you can add mayonnaise to a wide variety of foods, including sandwiches and salads, or use it as a dip. The easy availability of low-fat mayo also added to the condiment’s popularity as Americans become more health-conscious.

But as delicious as it is, it’s also important to make sure your mayo is good when eating your breakfast. This brief guide will help you understand why it’s so important to check whether mayo is spoiled and the signs to look for.

Signs Your Mayo Is Going Bad

Eating any expired food, including mayo, can often give you a stomach ache or diarrhea or cause you to experience nausea or vomiting.

But how can you tell if the mayo is bad? Here are some telltale signs:


Mold grows in the presence of moisture, so it can grow on mayo, too. When you see the mayo changing its color, it’s probably mold growth. Mold may grow in green or black clumps like you see in bread and other food items. It spreads through spores, which will cause the mayo to change its color from creamy white to a yellowish or brownish substance.

Once you see it changing color, throw away the mayo immediately. Some people think they can just remove the moldy part of the food and continue eating the rest. But that’s not a good idea. Since mold grows spores, it is not always visible to the eyes, so you may end up ingesting it without knowing.

Eating moldy food can be harmless or lead to nausea, diarrhea, shortness of breath, or fever. Since it can go either way, it’s best to err on the side of caution.


In case the mayo doesn’t change color but you have your doubts about its quality since it has been in your refrigerator or pantry for some time, check the smell.

Mayo has a distinct smell, and fans of the condiment will be familiar with it. It should have a very tame sour smell. But if you smell an intense odor, so much so that it almost smells like vinegar, then the mayo has probably turned bad.

The mayo is obviously bad when you open the jar and are immediately met with an acidic or pungent smell. Don’t try to salvage it by removing the top half. When it smells bad, every part of it is already bad.


Perhaps the mayo passed the color and smell tests, but when you ate it, it tasted bitter or sour. Mayo does have a tangy taste with a hint of saltiness. However, it should not be overwhelmingly sour or even slightly bitter.

When you are in doubt about the quality of the mayo because you forgot how long it has been in its storage place, just take a tiny taste of the condiment.

How To Tell If Mayo Is Bad

How Long Does Mayo Last?

Luckily, commercial mayonnaise comes in jars that tell you by when you should consume it.

Check the label for the “best before” or “best by” dates. The dates are sometimes referred to as the expiry dates even when they are not. The dates are suggestions on the best time to consume the mayo. It is an indication that, after the date on the label, the food product will start to lose its quality. But it is not yet expired.

As a rule of thumb, the mayo is still good two to three months after its “best before” or “best by” dates if it is unopened. But when you open it, make sure to do the color, smell, and taste test before adding it to your sandwich, salad, or whatever food you are making that needs the creaminess and slight tanginess of mayo.

Once the jar is opened, put it in the refrigerator right away. Unopened ones can be stored in the pantry.

In case you forget to put the opened jar of mayonnaise back in the refrigerator after using it, it will still be good for around eight hours. According to the United States Department of Agriculture, an opened jar of mayonnaise must be discarded if it was left in an environment above 50℉ temperature for over eight hours.

Eggs spoil easily when left unrefrigerated, and eggs are the main ingredient in mayo. Harmful bacteria will penetrate inside the condiment when left at room temperature for a long time.

An opened mayonnaise jar can last for at least two months as long as it is stored properly in the refrigerator. Ideally, you should write the date you opened the mayo on the jar, so you can monitor if it’s been two months or not.

However, homemade mayonnaise doesn’t have that type of lifespan. Experts suggest using up homemade mayo within two to three days, although it can last 7-10 days when stored properly in the refrigerator. Unlike commercial mayo, the homemade one doesn’t have preservatives that extend its shelf life.

What Happens When You Eat Bad Mayo?

How To Tell If Mayo Is Bad

Eating expired food, in general, will cause food poisoning. The Centers for Disease Control and Prevention notes that food-borne illnesses affect one in seven people, or around 48 million people, in the U.S. every year. Of that number, about 128,000 people are hospitalized.

Symptoms of food poisoning include the following:

  • Abdominal cramps
  • Diarrhea
  • Headache
  • Loss of appetite
  • Mild fever
  • Nausea
  • Vomiting
  • Weakness

In some cases, you will get better within 30 minutes. Without treatment, you may get better in a week. However, in dire cases, food poisoning may last for eight weeks.

Seek immediate help when your symptoms are worse, such as:

  • More than three days of diarrhea
  • High fever (102°F)
  • Difficulty speaking or seeing
  • Severe dehydration
  • Blood in urine

So, it’s important to be careful with how we store and consume food, including condiments like mayo.

How to Store Mayo – The Correct Way

To avoid getting Mayo spoiled, you should have some basic knowledge of storing mayo. I will tell you my personal way of storing Mayo. Below I have written my way of storing mayo, and by implementing the same way as mine, you will never ever face the problem of mayo going bad.

  1. What I always do before buying mayo, I check the best-before date, this way I can get to know exactly for how long my mayo will remain good.
  2. The next thing after purchasing mayo, I make sure that I am keeping it away from heat.
  3. I always keep in it cold temperature.
  4. If you have a fridge then the best way is to store mayo in the fridge only.

And that’s how I never ever faced the issue of mayo going bad, and I suggest you the same.

Also Read:

  1. Does Frozen Meat Weigh More Than Thawed Meat
  2. Can I Use Buttermilk Instead Of Milk?
  3. How to Reheat A Subway Sandwich


Americans love their mayo. But mayo lovers also need to keep track of their condiments. Consuming mayo that has spoiled can cause illness, which may range from a simple tummy ache to a high fever.

As soon as you see discoloration in your mayo or get a hint of a pungent smell, discard the jar immediately. The same goes when the condiment tastes overwhelmingly acidic or bitter. Remember to keep track of its “use by” date so you can enjoy this creamy condiment safely!


Campbell, A. & Rusciano, A. (2023, April 9). How to Tell if Mayo is Bad. WikiHow.

Ferdman, R. (2014, January 29). Ketchup Isn’t the King of American Condiments. Mayonnaise Is. Quartz.

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