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Can Mustard Go Bad?

If you don’t eat mustard regularly, it probably takes months for you to finish a jar.

And at a certain point, you start to wonder if mustard can actually go bad. And if it does, how to tell it’s bad.

Or perhaps you’ve just opened a jar, and need to know if you need to refrigerate the condiment or how long mustard lasts.

All of the above are fair questions, and we’re going to cover them in this article.

Sounds interesting? Read on.

Opened mustard jar
Opened mustard jar

Can Mustard Go Bad?

Like pretty much any food, mustard can go bad. But unlike most foods, it’s quite unlikely to happen.

On Wikipedia ([WIKI]), you can read that mustard can stay safe indefinitely due to its antibacterial qualities. And it makes sense if you look at the ingredients list.

Mustard includes mustard seeds, vinegar, and lemon juice, all of which last a long time. Plus vinegar and lemon juice are often used as preservatives in various foods and dishes.

Plus an unopened jar or squeeze bottle protects its contents from the outside world, so it’s not like a bunch of rogue bacteria will get inside and start to multiply.

In short, an unopened container should easily last many years without ever going bad. But even knowing that, I’d be quite hesitant to open mustard that’s 10 years old, and I guess you would be too.

Blob of mustard
Blob of mustard

Once you open the mustard, oxidation and general “access to the outside world” kick in.

Oxidation can cause browning ([WIKI]), and the condiment might dry out and lose some of its flavors after extended storage. But unless a bunch of microorganisms gets into the jar, it should still stay safe quite a long time.

Even though mustard can stay safe to eat indefinitely, it doesn’t mean it always does.

If it’s opened for more than a few months, make sure to regularly check the insides of the jar or bottle for any signs of mold. Giving the condiment a good whiff before pouring it onto your hot dog is also a good practice.

If there’s no organic growth inside the container and the mustard smells alright, it should be safe to eat. But safe to eat doesn’t always mean it’s good in terms of quality.

Speaking of which, let’s talk about how long mustard keeps well.

Mustard jar inside
Inside a mustard jar

How Long Does Mustard Actually Last?

Okay, so you already know that mustard can last indefinitely, at least in theory. But as I mentioned above, it doesn’t mean it will be tasty forever.

Similar to other popular condiments such as mayonnaise and ketchup, mustard degrades in quality over time. And while the speed of that process differs a bit between various styles of mustard, the general guidelines are pretty much the same.

That means they apply no matter if you have horseradish mustard, American mustard, or you went with the Dijon, French, or Chinese.

Date on a mustard jar
Date on a mustard jar

As long as the mustard is unopened, you can easily store it for a year or two past the date on the label.

An open jar of mustard should retain quality between 6 and 12 months if it sits in the fridge, and about a month or two if you store it at room temperature.

And what if the quality isn’t that good anymore? Should you just discard the mustard?

Not necessarily. Some of the typical quality issues can be easily fixed.

Mustard on sausages closeup
Mustard on sausages closeup

Mustard Quality Issues and How To Fix Them

Here are the quality issues that you might experience if your mustard has been opened for a while:

  • Separation. You can fix it by merely giving the condiment a good stir. Separation is a natural process and it’s harmless, so it’s not like you’re “fixing” spoiled mustard, or something.
  • Drying out. It usually happens if you keep the container unsealed for a long time, or when there’s only a little mustard left at the bottom. To fix it, try mixing some wine or vinegar ([WIKI]). Start with a teaspoon, and add more if required. Give that mustard a taste before using, and if the flavors didn’t blend well, just discard it.

If the mustard has turned bitter, it’s past its prime, and it’s probably best to throw it out.

Breakfast with sausages and mustard
Breakfast with sausages and mustard

How To Store Mustard? Do You Have To Refrigerate It?

An unopened container should sit in a cool and dark place, away from heat sources. Once you open the jar, it’s up to you if you refrigerate it or not.

As you can tell, the guidelines are quite similar to those of BBQ sauce or horseradish.

As I mentioned earlier, mustard won’t go bad if not refrigerated after opening, but its quality will degrade much faster.

If you accidentally left mustard out overnight, it’s not a big deal.

But as a general rule of thumb, keep this condiment refrigerated after opening. Most companies suggest this practice anyway.

I know restaurants often keep mustard bottles on tables, but the customers go through a single one within a few days tops. Keeping mustard at room temp for such a short period is not an issue.

Sausages with mustard, and veggies on the side
Sausages with mustard, and veggies on the side


  • Mustard can stay safe for months, but its quality can’t stay great forever.
  • As long as the jar is unopened, mustard retains quality for years; once opened, it keeps best for 6 months up to a year in the fridge.
  • You can fix dry mustard by mixing in some vinegar or vine, and separated mustard by simply stirring it.


Mustard jar
Mustard jar