Expired Mayonnaise Safety (Shelf Life Guide)

Commercial mayonnaise that is unopened and shelf-stable can generally be kept according to its label; refrigerate it after opening. Keep refrigerated mayonnaise and mayonnaise-based foods at 40°F (4°C) or below. Discard perishable food left out over 2 hours, or over 1 hour above 90°F (32°C). Homemade mayonnaise with raw eggs needs extra care and should be used within 3–4 days.

A date on a mayonnaise jar can be worrying, but the date alone does not tell the whole story. Safety depends on the product, whether it has been opened, how it was stored, and how long it sat out. These checks help you decide what to keep and what to discard without tasting it.

When I assess a jar, I start with its label and refrigeration history, not just its appearance. A clean-looking jar can still have an unsafe history, while a “best by” date is not, by itself, a universal safety cutoff. Use the steps below to make a calm, practical decision.

Product Type, Label Dates & Refrigerated Storage

Mayonnaise storage depends first on whether it is commercial or homemade and whether it is opened. Commercial products may be shelf-stable until opened if the label says so. Once opened, refrigeration matters. Homemade mayonnaise is different: it is perishable, needs refrigeration, and should not be treated as shelf-stable.

Check the product and date

Start by reading the storage instructions on the package. An unopened commercial jar labeled for pantry storage can generally stay there until opened, as long as it remains sealed and the package is intact. Follow any colder storage directions on the label.

A “best by” date mainly concerns quality; it is not a universal safety deadline. However, that does not mean every jar is safe after its date. If the package says “use by,” gives a specific discard instruction, or has special storage directions, follow those instructions. If you do not know how the product was stored, do not use the date as proof of safety.

After opening, promptly refrigerate commercial mayonnaise at 40°F (4°C) or below, or colder if the label directs. USDA FoodKeeper guidance lists about 2 months refrigerated for best quality for opened commercial mayonnaise. This is a quality guideline, not a promise that a jar remains safe for two months regardless of handling.

Homemade mayonnaise made with raw eggs carries a risk of harmful bacteria. Use pasteurized eggs, refrigerate it promptly, and use it within 3–4 days. Pasteurized eggs reduce risk but do not make the finished mayonnaise shelf-stable. When in doubt about when homemade mayonnaise was prepared, discard it.

Make a quick safety check

I use four checks before deciding whether to keep mayonnaise:

• Identify it: Is it commercial or homemade? Is the jar opened? What do the label and date say?
• Check its history: Has it stayed refrigerated when required? Do you know when it was opened or made?
• Inspect it: Discard it if you see mold, unusual discoloration, or notice an abnormal odor.
• Decide without tasting: Smell and appearance cannot prove that food is safe. Do not taste questionable mayonnaise to test it.

If the storage history is unknown, the safer choice is to discard it. That is especially important for homemade mayonnaise or an opened jar that may have been left warm.

Time-Temperature Checks and Safe Serving

Time and temperature are essential for deciding whether refrigerated mayonnaise and foods made with it are safe to keep. Keep them at 40°F (4°C) or below. If a perishable mayonnaise product or dish has been above that temperature too long, discard it. Refrigerating it again does not undo the time spent warm.

Use the two-hour and one-hour limits

The general limit for perishable food is 2 hours above 40°F (4°C). If the surrounding temperature is above 90°F (32°C), such as at an outdoor meal on a hot day, the limit is 1 hour. These limits apply to mayonnaise and mayonnaise-based foods, including sandwiches, potato salad, and pasta salad.

Count the time the food is out of refrigeration, including preparation and serving. If you cannot tell how long it has been out, do not assume it is safe. For a jar that is meant to be refrigerated after opening, return it to the refrigerator promptly rather than leaving it on the counter throughout a meal.

A temperature reading now cannot tell you how warm the food was earlier or for how long. If you are unsure whether a dish stayed cold, the clock and its history matter more than a single thermometer reading.

Remember mixed dishes

Mayonnaise in a sandwich, salad, or other mixed dish does not make that dish exempt from time limits. The acidity in commercial mayonnaise does not protect a finished dish from unsafe handling. Ingredients such as eggs, cooked potatoes, pasta, poultry, or seafood also affect the dish’s storage needs.

For example, a potato salad can look and smell normal after sitting out too long and still be unsafe to eat. Do not rely on mayonnaise’s smell, appearance, or acidity to judge a mixed dish. If the dish exceeded the time limit, discard it instead of chilling it again or stirring it into fresh food.

Handling, Cross-Contamination & Disposal

Clean handling helps prevent germs from moving into a jar or onto food. Use a clean utensil each time, keep the jar rim and lid clean, and avoid letting a utensil that touched other food go back into the mayonnaise. If storage or handling was unsafe, discard the food rather than trying to repair it.

Keep the jar clean and cold

Use a clean spoon or spreader, and do not double-dip a utensil that has touched bread, meat, or another ingredient. Close the lid and return the jar to the refrigerator promptly. Store it in line with the label, at 40°F (4°C) or below if refrigeration is required.

If you transfer mayonnaise to another container, use a clean, food-grade, nonreactive container with a lid. Mark it with the date you opened or prepared the mayonnaise. This makes it easier to track time in the refrigerator, especially for homemade mayonnaise, which should be used within 3–4 days.

Know when to throw it out

Discard mayonnaise if it has mold, unusual discoloration, or an abnormal odor. Also discard it if it has exceeded the time-temperature limits or if you cannot verify its storage history. Do not taste it to decide whether it is safe.

Do not try to rescue mayonnaise or a mayonnaise-based dish by reheating it, chilling it again, or mixing it with fresh ingredients. Those steps do not make food safe after it has spent too long at unsafe temperatures. Put discarded food in a closed bag or container, then wash hands and clean any surfaces it touched.

Serving Presentation and Chilled Holding

Serving mayonnaise-based foods safely means keeping them cold from preparation through the meal. Put out only what you expect to serve, keep the rest refrigerated, and track the time at room temperature. Attractive presentation should not come at the cost of leaving perishable food warm for too long.

For a meal that lasts, set a small portion on the table and replenish it from the refrigerator as needed. You can place the serving dish inside a larger container with ice to help keep it cold; keep the food dish stable and avoid letting meltwater enter the food. A food thermometer can check temperature, but it cannot replace tracking how long the dish has been out.

Do not combine fresh mayonnaise salad with leftovers that have already been on the table. If the served portion crosses the 2-hour limit, or the 1-hour limit when the air is above 90°F (32°C), discard it. Keep remaining portions cold and separate.

A practical example

Imagine you open a commercial jar for lunch, then use it to make sandwiches for a picnic. The jar belongs back in the refrigerator promptly. The sandwiches also need cold storage; the jar’s commercial acidity does not extend the sandwiches’ safe time out. If the picnic is hot and the sandwiches have been above 40°F for more than an hour, discard them.

This is the key distinction: the storage rules for the jar do not automatically cover food made with it. Treat the finished dish as perishable and use the time limits.

Frequently Asked Questions

These quick answers address common questions about dates, storage, and signs of spoilage. They are a starting point, not a substitute for the package instructions or a known storage history. When the time or temperature is uncertain, do not taste the food to decide; discard it.

Can I eat unopened mayonnaise after its “best by” date?
A “best by” date is mainly about quality, not a universal safety cutoff. Check the package instructions and condition, and do not use a jar if its storage history or seal is in doubt.

How long does opened commercial mayonnaise last in the fridge?
USDA FoodKeeper guidance gives about 2 months refrigerated for best quality. Keep it at 40°F (4°C) or below, follow the label, and remember that the time is not a safety guarantee.

Does mayonnaise need to be refrigerated before opening?
Follow the label. Commercial mayonnaise labeled shelf-stable can generally be stored unopened as directed. Refrigerate it after opening unless the package gives different instructions.

What if mayonnaise sat out overnight?
Discard it if it is a perishable product that was above 40°F for more than 2 hours. Do not taste it or put it back in the refrigerator for later use.

Can I eat potato salad that sat out for a few hours?
Discard it if it was above 40°F for more than 2 hours, or more than 1 hour when the air was above 90°F. A normal smell or appearance does not prove it is safe.

How long can homemade mayonnaise last?
Homemade mayonnaise made with raw eggs should be refrigerated promptly and used within 3–4 days. Use pasteurized eggs, and do not treat homemade mayonnaise as shelf-stable.

Can I tell if mayonnaise is unsafe by smell or appearance?
Mold, unusual discoloration, or an abnormal odor are reasons to discard it. But mayonnaise can look and smell normal and still be unsafe after poor temperature control.

Does adding mayonnaise make a sandwich safe at room temperature?
No. A sandwich made with mayonnaise is still perishable. Keep it cold and follow the 2-hour limit, or 1 hour when the air is above 90°F.

Can I chill mayonnaise again after it has sat out too long?
No. Chilling it again does not undo time spent above safe refrigeration temperature. Discard it if it exceeded the time limit.

What temperature should my refrigerator be?
Keep it at 40°F (4°C) or below. Use a refrigerator thermometer if you are unsure, and follow colder storage directions on the product label.

The most useful rule is to combine the label, product type, and storage history. Keep refrigerated products cold, track how long dishes sit out, and discard food when the limit is exceeded or its history is unknown.

(This article was written by one of our staff writers, Richard K. Ellison. Visit our Meet the Team page.)