Does Mayo Need to be Refrigerated?

Does mayo need to be refrigerated? Mayonnaise is a must-have for salads, sandwiches and for even for making crab cakes, but whether you’re using store-bought mayo or whipping up a homemade batch, proper storage is key to maintaining flavor, freshness, and food safety.

In this guide, we’ll cover:

• When mayo needs refrigeration
• How long mayo lasts
• Best storage practices for homemade vs. store-bought mayo
• Signs of spoilage
• Official food safety guidelines

Here’s everything you need to know:

Does Mayo Need to Be Refrigerated?

Most store-bought commercial mayonnaise is shelf-stable and doesn’t require refrigeration until after you open the jar (or bottle). This is because it contains preservatives, pasteurized eggs, and acidic ingredients that help prevent bacterial growth.

So yes: once it’s opened, refrigerate mayo to maintain freshness and flavor.

Here’s why:

• Refrigeration slows spoilage and prevents bacterial contamination.
• Preservatives lose effectiveness over time, especially when exposed to air.
• Temperature fluctuations (like leaving it out during a meal) can shorten shelf life.

How Long Does Store-Bought Mayo Last?

Unopened: Up to 1 year in a cool, dry pantry.
Opened (Refrigerated): 2–3 months for best quality.
Opened (Room Temperature): 1 month max, but flavor may degrade faster.

For official food storage guidelines, check the USDA’s recommendations.

Does Homemade Mayo Need to Be Refrigerated?

Unlike store-bought varieties, you must refrigerate homemade mayo immediately because it lacks commercial preservatives.

One of its main ingredients is raw egg yolks, which can spoil quickly when exposed to air and warm room temperatures.

Mayonnaise Ingredients & Their Role in Preservation

Understanding the ingredients in mayo can help explain why it lasts and how it spoils:

Egg Yolks: Provide emulsification but can spoil quickly if raw.
Oil: Acts as a stabilizer but can turn rancid over time.
Vinegar/Lemon Juice: Adds acidity, which helps prevent bacterial growth.
Salt & Sugar: Extend shelf life by reducing moisture content.

Do Different Mayo Types Have Different Storage Needs?

Traditional Mayo: Requires refrigeration after opening.
Vegan Mayo: Often contains stabilizers but still benefits from refrigeration.
Flavored Mayo (Chipotle, Garlic, etc.): May spoil faster from added ingredients. 
Japanese Mayo (Kewpie): Contains extra egg yolk, making refrigeration essential.

It’s best to check the label for individual storage recommendations, but either way the refrigerator is mayo’s friend.

Does Mayo Go Bad Faster in Certain Conditions?

✔ Warm Climates: Mayo spoils faster if left unrefrigerated in hot environments.
✔ Cross-Contamination: Using dirty utensils can introduce bacteria.
✔ Exposure to Air: Leaving the lid loose can speed up oxidation.

Best Storage Practices for Homemade Mayo

• Refrigerate immediately after making to prevent bacterial growth.
• Store in an airtight container to limit air exposure.
• Use within 5–7 days for best flavor and safety.
• Freeze for up to 3 months if making a large batch.

For more food safety insights, refer to the FDA’s refrigerator storage chart.

What Do Experts Say About Storage?

According to FoodSafety.gov, opened mayonnaise should be thrown away if left above 50°F (10°C) for over 8 hours.

Signs Your Mayo Has Gone Bad

Even refrigerated mayo can spoil.

Watch for these warning signs:

• Mold or discoloration (especially around the lid).
• Off-putting smell (icky, sour or rancid).
• Separation of ingredients (excessive wateriness).
• Unusual taste (sour, bitter or overly acidic).

If you notice any of these, discard the mayo immediately.

How Does Mayo Spoil?

Mayonnaise, like any condiment, can spoil over time from exposure to air, moisture, and bacteria.

While its high acidity and fat content help preserve it, improper storage can cause it to go bad.

Factors That Cause Spoilage

Oxidation: Once opened, mayo is exposed to air, which can cause ingredients to break down and alter flavor.
Bacterial Growth: If contaminated (e.g., using a dirty spoon), bacteria can multiply, leading to spoilage.
Moisture Exposure: Excess moisture can dilute preservatives, making the mayo more susceptible to mold.
Temperature Fluctuations: Leaving mayo out for extended periods, especially in warmer temperatures, can quicken spoilage.

How to Prevent Mayo from Spoiling

✔ Store in an airtight container to limit air exposure.
✔ Refrigerate after opening to slow bacterial growth.
✔ Use clean utensils to prevent contamination.
✔ Check expiration dates and discard mayo past its shelf life.

FAQ: Does Mayo Need to Be Refrigerated?

1. Does mayo need to be refrigerated after opening?

Yes. Store-bought mayo should be refrigerated after opening to maintain freshness. Homemade mayo should always be refrigerated since it lacks preservatives.

2. Can you store mayo at room temperature after opening?

Store-bought (jarred or bottled) mayo can be kept at room temperature for a short period (up to a month), but refrigeration is recommended for long-term freshness. Homemade mayo should always be refrigerated.

3. What ingredients help mayo last longer?

Vinegar & Oil: Natural preservative that slows bacterial growth.
Lemon Juice: Adds acidity, which prevents spoilage.
Salt & Sugar: Help extend shelf life.

4. How can I tell if it’s bad?

• Mold or discoloration (especially around the lid).
• Sour or rancid smell.
• Separation of ingredients (excessive wateriness).
• Unusual taste (bitter or overly acidic).

5. Can mayo be frozen?

Yes, but the experts over at Hellman’s don’t recommend it. While freezing can extend shelf life up to 3 months, it can change the texture and cause the ingredients to separate.

If you decide to freeze, store in freezer-safe containers for best results.

6. How do I thaw frozen mayo?

Refrigerator method: Thaw overnight for best texture.
Quick method: Stir well after thawing to restore consistency.

7. Does mayo expire?

Yes. Even store-bought mayo has a best-by date, though it may still be safe to eat beyond that if stored properly. Always check for signs of spoilage before consuming.

8. Are there any official food safety guidelines for storage?

While the FDA and USDA don’t have mayo-specific guidelines, they recommend refrigerating homemade sauces to prevent bacterial growth.

You can check their general food storage recommendations at:

USDA Shelf-Stable Food Guidelines
FDA Refrigerator and Freezer Storage Chart

Final Thoughts: Does Mayo Need to Be Refrigerated?

✔ Store-bought mayo can last 1 year unopened, but should be refrigerated after opening.
✔ Homemade mayo should always be refrigerated and used within 5–7 days.
✔ Proper storage ensures longer shelf life, better taste, and food safety.

Further Reading

Does BBQ Sauce Need to Be Refrigerated?

Does Ketchup Go Bad? Everything You Need to Know.

Should Mustard Be Refrigerated?

Does Peanut Butter Go Bad?

Should Soy Sauce Be Refrigerated? 

Should Honey Be Refrigerated?