How Long Mayonnaise Stays Fresh in Your Refrigerator

Unopened mayonnaise lasts three to four months past the printed date; opened jars last about two months

Unopened mayonnaise in your refrigerator will stay safe to eat for three to four months after the "best by" date printed on the jar. Once you open it, the clock resets—an opened jar lasts about two months from the day you first use it, not from the date on the label. The printed date is the manufacturer's estimate of peak quality, not a hard expiration. Mayonnaise is acidic and high in oil, which naturally preserves it, but once air and a spoon enter the jar, oxidation and contamination begin.

The reason mayonnaise lasts so long is its chemistry. Eggs, oil, and vinegar or lemon juice emulsify into a stable product that resists bacterial growth. The acidity (pH below 4) is the real guardian—bacteria struggle to survive in that environment. This is why homemade mayonnaise, which often has less acid than store-bought versions, spoils faster and should be used within a week.

Key Takeaways

• Store unopened mayonnaise in the refrigerator, and it will last three to four months past the printed date.
• Once opened, use mayonnaise within two months; mark the jar with the opening date if the label doesn't have space.
• Keep the jar sealed between uses and always use a clean spoon to scoop, never double-dip from a serving dish.
• Discard mayonnaise if you see mold, smell sourness or fermentation, or notice separation that doesn't mix back in.
• Homemade mayonnaise lasts only about one week in the refrigerator because it lacks the preservatives in commercial versions.

Signs mayonnaise has gone bad

Visible mold is the clearest sign to throw the jar away. Mold can grow on the surface or inside the jar, especially if the lid was left loose or if a wet spoon was used. Even if you scrape off the visible mold, spores have already spread through the jar—discard it entirely.

Smell is your second line of defense. Fresh mayonnaise has a mild, slightly tangy egg-and-oil aroma. If it smells sour, fermented, or off in any way, do not taste it. A sour smell means bacteria or yeast has colonized the jar. Separation—where oil pools on top and doesn't mix back in when you stir—can happen naturally with age, but if it smells wrong alongside the separation, throw it out.

Discoloration is less common but worth noting. Mayonnaise should be pale yellow or off-white. If it has turned brown, gray, or pink, something has contaminated it. Trust your instinct: if the jar looks wrong, it probably is.

How to store mayonnaise to extend its life

Keep the jar in the coldest part of your refrigerator, usually the back of a shelf rather than the door. Refrigerator doors experience temperature swings every time you open them, which speeds up spoilage. A stable, cold environment slows oxidation and bacterial growth.

Always use a clean spoon and never double-dip. When you scoop mayonnaise into a bowl for a sandwich or salad, use a fresh spoon each time. Double-dipping introduces bacteria from your mouth or other foods back into the jar. If you're serving mayonnaise at a table, transfer what you need to a small dish and leave the jar in the refrigerator.

Seal the lid tightly after every use. Air exposure causes oxidation, which breaks down the emulsion and creates off-flavors. A loose lid also allows mold spores and bacteria to enter. If the original lid is damaged or doesn't seal well, transfer the mayonnaise to a clean container with a tight-fitting lid.

Write the opening date on the jar with a marker if it is not already printed. Most store-bought jars have a "best by" date, but once opened, you need to track when you first used it. A simple date on the lid or side of the jar takes the guesswork out of deciding whether it is still good.

Mayonnaise in different refrigerator zones

The back of the middle or lower shelf is ideal. These areas stay coldest and most stable. Avoid the door entirely—it is the warmest part of your refrigerator and experiences the most temperature fluctuation. If your refrigerator has a dedicated condiment shelf, that works if it is not on the door.

If you have a drawer or compartment labeled "cold zone" or "fresh zone," mayonnaise does not belong there. Those drawers are designed for vegetables and meats that need humidity and slightly warmer temperatures. Mayonnaise needs consistent, steady cold, which the main shelves provide.

Keep mayonnaise away from strong-smelling foods like onions, garlic, or fish. Although mayonnaise is sealed, it can absorb odors over time, especially if the lid is not airtight. A small gap or a slightly loose seal is enough for smell to transfer.

Homemade mayonnaise and food safety

Homemade mayonnaise made with raw eggs carries a small risk of salmonella, especially if the eggs are not from a reliable source. Even if you use pasteurized eggs, homemade mayonnaise lacks the preservatives and acidity levels of commercial versions. It will last only about one week in the refrigerator, sometimes less.

If you make mayonnaise at home, use pasteurized eggs or pasteurized egg products to reduce the risk of foodborne illness. Store it in a clean, sealed container and date it immediately. Do not keep it longer than one week, even if it looks and smells fine. The risk is not worth the small amount of time saved.

Commercial mayonnaise is safer for longer storage because manufacturers use pasteurized eggs and carefully controlled acid levels. If you prefer homemade flavor but want longer shelf life, look for recipes that use pasteurized eggs and extra lemon juice or vinegar.

What to do with mayonnaise nearing its expiration

If your opened jar is approaching the two-month mark, use it up in dishes where it will be heated or mixed with other ingredients. Mayonnaise in tuna salad, potato salad, or coleslaw will be consumed quickly and the other ingredients provide additional preservation. Avoid using old mayonnaise for raw applications like spreading on bread, where its condition is more noticeable.

If you have unopened jars approaching their printed date, they are still safe but may have lost some flavor or texture. Use them first, before opening newer jars. Rotate your stock so older jars get used before newer ones.

Do not freeze mayonnaise. The emulsion breaks when frozen, and thawing will not restore it. You will end up with separated, unusable mayonnaise. Refrigeration is the only storage method that works.

Frequently Asked Questions

Can I eat mayonnaise after the date on the jar?

Yes, if it is unopened and has been refrigerated. The printed date is when the manufacturer guarantees peak quality, not when it becomes unsafe. Unopened mayonnaise lasts three to four months past that date. Once opened, use it within two months from when you first opened it, not from the printed date.

Why does my mayonnaise separate?

Separation happens naturally as mayonnaise ages. Oil and water begin to break apart, especially if the jar has been stored in a warm spot or opened and closed many times. Stir it back together if it still smells and looks normal. If separation happens alongside a sour smell or visible mold, discard the jar.

Is it safe to leave mayonnaise out on the counter during a meal?

Mayonnaise can sit out for a few hours during a meal, but do not leave it unrefrigerated for more than four hours total. The acidity protects it somewhat, but bacteria can still grow in warm conditions. Return it to the refrigerator as soon as the meal is done.

Does store-bought mayo last longer than homemade?

Yes, significantly. Store-bought mayonnaise lasts two months after opening because of added preservatives and controlled acidity. Homemade mayonnaise lasts only about one week because it lacks these stabilizers. If you make it at home, use pasteurized eggs and store it in a sealed container.

What if I forgot to refrigerate mayonnaise overnight?

If it was unopened and left out for one night, it is still safe—refrigerate it and use it normally. If it was opened and left out overnight, discard it. The risk of bacterial growth is too high after eight or more hours at room temperature, even though mayonnaise is acidic.