How Long Does Unopened Mayonnaise Last?
An unopened jar of commercially produced mayonnaise can often maintain its quality until the date printed on the packaging when stored according to the label.
Some products are shelf-stable before opening, while others require refrigeration. Always check the packaging rather than assuming every mayonnaise product should be stored the same way.
You may sometimes see mayonnaise that is past its best-before date, but this does not automatically mean it is unsafe. However, a sell-by, use-by, or expiration date can have a different meaning depending on the product and local labeling rules.
When in doubt, follow the manufacturer's guidance.
How Long Does Opened Mayonnaise Last?
Once you open a jar, proper storage becomes especially important.
Many commercial mayonnaise manufacturers recommend using opened mayonnaise within approximately two months when continuously refrigerated. Check the specific product label because recommendations can vary.
To help preserve its quality:
Refrigerate it promptly after opening.
Keep the lid tightly closed.
Use clean utensils every time.
Avoid leaving the jar on the counter during meals.
Never return used mayonnaise from a plate or serving bowl to the original container.
If you notice anything unusual about the product or know it has been stored incorrectly, don't rely on the two-month guideline. Throw it away if there is any reason to suspect contamination.
How Can You Tell if Mayonnaise Has Gone Bad?
Mayonnaise does not always spoil in an obvious way, so it's important to pay attention to changes in its appearance, smell, and storage history.
Here are some warning signs to look for.
1. An Unusual or Sour Smell
Fresh mayonnaise has a mild, slightly tangy smell. If it develops an unpleasant sour, rancid, or otherwise unusual odor, it may have deteriorated.
Do not taste mayonnaise to determine whether it is safe. If the smell seems wrong, discard it.
2. Changes in Color
Mayonnaise is usually creamy white, pale yellow, or another consistent shade depending on the ingredients.
If you notice unusual discoloration, dark spots, or visible mold, throw the entire container away.
Do not simply remove the affected portion and continue using the rest.
3. Unusual Texture
A little separation can sometimes happen in mayonnaise, particularly after prolonged storage or temperature changes. However, significant separation, unexpected lumps, or a texture that looks very different from when you opened it can indicate a problem.
If the product also has an unusual smell or appearance, discard it.
4. Visible Mold
Mold is a clear reason to throw mayonnaise away.
Because mayonnaise is a moist food, mold may spread beyond the area you can see. Scraping off the visible mold does not make the remaining contents safe.
5. An Unknown Storage History
Sometimes the biggest warning sign isn't the mayonnaise itself but how it has been handled.
If the jar has been left out for several hours, exposed to excessive heat, or repeatedly contaminated with used utensils, it may no longer be safe even if it looks normal.
Remember that harmful bacteria cannot always be detected through smell, appearance, or taste.
How Long Can Opened Mayonnaise Sit at Room Temperature?
Mayonnaise should not be left at room temperature for extended periods.
For perishable foods, the general food-safety rule is to refrigerate them within two hours. If the surrounding temperature is above 90°F (32°C), that window drops to one hour.
This is particularly important when mayonnaise is mixed with other ingredients, such as eggs, chicken, tuna, or potatoes.
For example, a bowl of homemade egg salad sitting on a picnic table in warm weather can become unsafe much faster than a properly refrigerated jar of commercial mayonnaise.
To keep things safe:
Take out only the amount you need.
Return the jar to the refrigerator promptly.
Keep serving bowls chilled when possible.
Avoid leaving mayonnaise-based salads outdoors in hot weather.
Discard perishable dishes that have been left out beyond the recommended time.
Even if mayonnaise smells perfectly normal, that does not prove it is safe after improper storage.
The Best Way to Store Mayonnaise
Proper storage helps maintain mayonnaise's flavor, texture, and quality.
1. Keep It Refrigerated
After opening, store commercial mayonnaise in the refrigerator at 40°F (4°C) or below.
A consistent refrigerator temperature helps slow bacterial growth and protects the product's quality.
2. Keep the Container Tightly Closed
Always replace the lid after using mayonnaise.
A properly closed container helps protect the contents from outside contaminants, odors, and unnecessary exposure to air.
3. Use Clean Utensils
One of the easiest ways to contaminate mayonnaise is by dipping a used knife or spoon directly into the jar.
For example, spreading mayonnaise on a sandwich and then returning the same knife to the container can introduce crumbs and bacteria.
Instead, use a clean spoon or knife each time.
4. Avoid Storing It in the Refrigerator Door
The refrigerator door experiences more temperature changes because it is opened frequently.
For more consistent cooling, keep mayonnaise on an interior shelf rather than in the door whenever possible.
5. Write Down the Opening Date
If you regularly forget when you opened a jar, write the date on a small piece of tape and place it on the lid.
This simple habit makes it easier to keep track of how long the product has been refrigerated.
Does Homemade Mayonnaise Last as Long as Store-Bought Mayo?
No. Homemade mayonnaise generally has a much shorter storage life.
Commercial mayonnaise is produced under controlled conditions and commonly uses pasteurized eggs. Homemade recipes may use raw eggs, which can carry harmful bacteria such as Salmonella.
For this reason, homemade mayonnaise should generally be refrigerated promptly and used within three to four days. If the recipe contains raw or lightly cooked eggs, using pasteurized eggs is a safer choice.
You should also:
Prepare it with clean equipment.
Use fresh ingredients.
Store it in a clean, covered container.
Keep it refrigerated at 40°F (4°C) or below.
Avoid leaving it at room temperature.
If you want homemade mayonnaise to last longer, consider preparing smaller batches rather than keeping a large container for several weeks.
Can You Freeze Mayonnaise?
Freezing mayonnaise is generally not recommended.
Mayonnaise is an emulsion, meaning oil and water-based ingredients are combined into a smooth, creamy mixture. Freezing and thawing can cause this mixture to separate.
After thawing, mayonnaise may become watery, grainy, or oily, even if it was safe to eat before freezing.
The flavor and texture may also change, making it unsuitable for sandwiches, dips, and dressings.
For the best quality, keep mayonnaise refrigerated and use it within the manufacturer's recommended period after opening.
What About Egg Salad, Potato Salad, and Other Mayo-Based Dishes?
It's important to distinguish between a jar of commercial mayonnaise and prepared foods made with mayonnaise.
A jar of commercial mayonnaise is an acidic product, but once you mix it with cooked eggs, potatoes, chicken, tuna, or other ingredients, the finished dish has different food-safety characteristics.
Most homemade egg salad, chicken salad, tuna salad, and potato salad should be refrigerated promptly and used within three to four days.
Keep these dishes at 40°F (4°C) or below, and don't leave them at room temperature for more than two hours, or one hour when temperatures exceed 90°F (32°C).
Frequently Asked Questions
1. Can I eat mayonnaise that has been open for three months?
It depends on the product and how it has been stored, but three months is beyond the approximately two-month recommendation commonly given by commercial mayonnaise manufacturers for opened jars. Check the label. If it is past the recommended period, the safest choice is to discard it.
2. Does mayonnaise need to be refrigerated before opening?
Not always. Many commercially produced mayonnaise products are shelf-stable until opened, while some varieties require refrigeration from the beginning. Follow the instructions printed on the container.
3. Why does my mayonnaise look watery?
Mayonnaise can sometimes separate, especially after temperature changes or prolonged storage. However, unusual separation accompanied by discoloration, an unpleasant odor, or other changes is a reason to discard it.
4. Can bad mayonnaise make you sick?
Yes. Contaminated or improperly stored mayonnaise and mayonnaise-based foods can cause foodborne illness. Symptoms may include nausea, vomiting, stomach cramps, diarrhea, and fever. Seek medical advice if symptoms are severe, persistent, or concerning.
5. Does mayonnaise go bad faster in summer?
It can become unsafe more quickly if left at warm temperatures. During summer picnics and outdoor meals, keep mayonnaise and mayonnaise-based dishes chilled and follow the one-hour rule when temperatures exceed 90°F (32°C).
6. Is it safe to eat mayonnaise past its best-before date?
A best-before date generally relates to quality, but labeling rules and product recommendations vary. An unopened, properly stored product may retain quality beyond that date, but you should follow the manufacturer's instructions and never use a product with signs of spoilage or an uncertain storage history.
7. Can I use mayonnaise if it smells normal but has been left out overnight?
No. A normal smell does not guarantee safety. If opened mayonnaise has been left at room temperature overnight, discard it rather than risking foodborne illness.
Final Thoughts
Mayonnaise is a convenient kitchen staple, but knowing how to store it properly can help you avoid unnecessary waste and reduce the risk of foodborne illness.
Commercial mayonnaise generally keeps for a relatively long time when unopened and properly stored. Once opened, many manufacturers recommend using it within approximately two months in the refrigerator. Homemade mayonnaise and prepared salads containing mayonnaise have much shorter storage lives.
Remember the basics: keep mayonnaise properly refrigerated, close the container tightly, use clean utensils, and avoid leaving it out for extended periods.
And if something about its smell, appearance, or storage history seems questionable, it's always better to throw it away than take a chance.
