How Long Does Mayonnaise Last?

How long does mayonnaise last in the fridge after opening?

Opened commercial mayonnaise lasts about 2 months in the refrigerator. The acidity from vinegar or lemon juice (mayo typically has a pH between 3.6 and 4.0) combined with the high oil content makes mayo inhospitable to most bacteria, which is why it keeps longer than many condiments. Store it on a refrigerator shelf rather than the door, where temperature fluctuates with each opening; refrigerator doors run 5-10 degrees warmer than shelves on average. Always use clean utensils when scooping mayo; the most common spoilage source is double-dipping with a knife that touched raw meat or other contaminated foods. Light mayo, olive oil mayo, and avocado oil mayo may have slightly shorter fridge lives (about 6-8 weeks) due to different formulations. Vegan mayonnaise generally matches conventional mayo's timeline.

How long does unopened mayonnaise last?

Unopened mayonnaise lasts 3-4 months past the printed best-by date when stored in a cool, dark pantry below 70 degrees F. The shelf life depends more on temperature than time; mayo stored in a warm cabinet near the stove or above the refrigerator degrades faster than mayo in a cool pantry. The best-by date is a quality indicator from the manufacturer, not a safety cutoff, so a few months past doesn't make it dangerous. Once opened, all mayo (regardless of how new the jar is) needs refrigeration; opening exposes the mayo to airborne bacteria and breaks the manufacturer's seal. Squeeze bottles and individual packets follow the same timeline; packets last 6-9 months past the printed date because the smaller volume limits oxygen exposure. Check for separation, discoloration, or off odors before using mayo past its date.

Can you leave mayonnaise out at room temperature?

No, opened mayonnaise should not be left at room temperature for more than 2 hours. While the mayo itself is acidic and not particularly hospitable to bacteria, it can still spoil and cause illness if left out, especially if it gets contaminated by other foods. For picnics and outdoor events, keep mayo-containing dishes (potato salad, sandwiches, chicken salad, dips) in a cooler at or below 40 degrees F with ice packs that last the duration of the event. The 2-hour rule drops to 1 hour when the ambient temperature is above 90 degrees F (typical summer outdoor temperatures). Discard any mayonnaise or mayo-containing food that's been out longer than these limits, even if it looks and smells fine.

How do you tell if mayonnaise has gone bad?

Spoiled mayonnaise shows clear warning signs. The color may darken from cream-white to yellowish, brownish, or develop dark spots; the texture separates with oil pooling on the surface that won't mix back when stirred (some minor separation is normal, but persistent unmixable oil layers are a warning); the smell becomes sour, sharp, or fermented rather than the neutral, slightly tangy smell of fresh mayo; and the consistency may become unusually thick, lumpy, or watery. Mold growth (any color, including white or green specks on the surface or around the rim) means immediate disposal. Trust your nose: if mayo smells off, discard it even if it's within the 2-month window. When in doubt, throw it out; the risk of food poisoning isn't worth keeping questionable jars.