That half-used jar of mayonnaise sitting in the back of your refrigerator may look perfectly normal, but appearance alone doesn’t tell you whether it’s still safe to eat.
Knowing how long mayo lasts—and recognizing the signs that it has gone bad—can help you avoid unnecessary food waste while reducing the risk of foodborne illness.
How Long Does Opened Mayonnaise Last?
For commercially prepared mayonnaise, a commonly recommended guideline is to use an opened jar within about two months when it has been continuously refrigerated and handled properly.
An unopened jar generally can be kept until the date printed on the package, provided it has been stored according to the manufacturer’s instructions.
Keep in mind that storage conditions matter. A jar that has repeatedly been left out on a warm counter may not remain safe for as long as one that has stayed properly chilled.
Check More Than the Date
A date on the package is useful, but it shouldn’t be the only thing you consider.
Before using older mayonnaise, look for noticeable changes such as:
- Mold
- An unusual or significantly altered color
- A strong sour, rancid, or unpleasant odor
- A major change in texture or consistency
If you see mold or notice significant spoilage, it’s safest to discard the entire container rather than trying to remove the affected portion.
And don’t taste questionable mayonnaise simply to determine whether it’s still good. When a food looks or smells suspicious, throwing it away is the safer choice.
What If Mayo Is Left Out?
Temperature is another important part of food safety.
Perishable foods should generally be refrigerated within two hours. If the surrounding temperature is above 90°F (32°C), that window drops to about one hour.
This becomes particularly important during outdoor gatherings, picnics, parties, and barbecues.
Foods such as potato salad, chicken salad, coleslaw, and other prepared dishes containing mayonnaise can spend too much time in the temperature danger zone if they’re left sitting outside for hours.
When serving these foods, keep them chilled and return leftovers to the refrigerator promptly.
Store Mayo Properly
You can also help preserve the quality of mayonnaise by following a few simple habits.
Keep an opened jar refrigerated and tightly sealed when you’re not using it.
Always use clean utensils rather than dipping utensils that have already touched other foods back into the jar. Cross-contamination can introduce bacteria and other contaminants.
It’s also a good idea to avoid leaving the jar sitting on the counter for extended periods while preparing a meal.
Homemade Mayo Is Different
Homemade mayonnaise shouldn’t automatically be treated like commercial mayonnaise.
Depending on the recipe and ingredients, homemade mayo can have a considerably shorter refrigerated shelf life. This is particularly important when raw or lightly cooked eggs are used.
If you’re making mayonnaise at home, follow a reliable recipe and appropriate food-safety guidance for the ingredients you’re using.
What About Mayo-Based Leftovers?
Sometimes the mayonnaise itself isn’t the biggest concern.
Once mayo is mixed into foods such as chicken salad, egg salad, or potato salad, the entire prepared dish needs to be treated as a perishable food.
The amount of time it has spent at room temperature, how it was prepared, and how quickly it was refrigerated all matter.
If a dish has been sitting out too long, don’t rely solely on its appearance or smell to decide whether it’s safe.
When in Doubt, Throw It Out
Food can sometimes appear completely normal while still posing a health risk.
That’s why questionable mayonnaise isn’t worth taking chances with.
If you can’t remember how long an opened jar has been sitting in the refrigerator, or it has been stored improperly, replacing it is usually the simplest option.
A new jar of mayonnaise is inexpensive compared with the potential consequences of eating spoiled or improperly stored food.
The Bottom Line
For commercially prepared mayonnaise, about two months after opening is a useful general guideline when the jar has remained properly refrigerated. Unopened mayonnaise can generally be kept until its package date when stored correctly.
However, storage temperature and handling are just as important as the date.
Keep opened mayo cold, seal it properly, use clean utensils, and discard it if you notice obvious spoilage or if it has been left unrefrigerated for too long.
When you’re uncertain about an older jar, the safest choice is simple: don’t taste it to find out—when in doubt, throw it out.
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