How Long Does Oat Milk Last?

Written by: Kelly Donovan

In the last five years, oat milk has gone from a complete unknown in the global grocery world to the second most popular plant-based milk – and shows absolutely no signs of slowing down. The demand for oat milk is almost unprecedented.

At the same time, supply to meet this demand has slowed down quite a bit, and people are hoping their oat milk will stretch a little longer because of it. 

Just how long will oat milk last before going bad, though? You can expect oat milk to stay fresh for anywhere between 7 and 10 days after opening it.

Below, we dig a little deeper into the ins and outs of oat milk, how long it will keep before it spoils, how to properly store oat milk to extend its longevity, and so much more.

Let’s get right into it, shall we?

Does Oat Milk Go Bad?

Oat milk, just like traditional dairy (and most other plant-based milk), has a shelf life before it spoils – and that shelf life is a little bit shorter than most people might expect.

According to most oat milk manufacturers, you can get anywhere between seven days and about ten days of “freshness” out of your oat milk.

That clock starts when you open your container, though.

Shelf-stable oat milk (milk that doesn’t have to be refrigerated right from the jump) can last a little longer, provided it hasn’t been opened yet.

That kind of oat milk can last a couple of months before it goes bad!

You should also know that oat milk producers recommend that refrigerate oat milk within two or three hours of opening it.

Let it sit out any longer than that, and you risk spoilage.

You don’t want to leave oat milk out overnight after opening it before it hits the refrigerator, that’s for sure.

does oat milk go bad

How to Store Oat Milk

Storing oat milk is pretty straightforward, but you have to be careful about how you go about it.

Here's how to store store-bought oat milk and homemade oat milk to extend its shelf life.

Storing Store-Bought Oat Milk

You’ve got two different kinds of store-bought oat milk available on the market today. 

On the one hand, you have the shelf-stable oat milk mentioned above.

This kind of oat milk is sold at room temperature and will be found in the inner aisles of your grocery store. 

Shelf-stable oat milk can be stored in your pantry at room temperature for at least a couple of months (though you’ll want to check the expiration date on your oat milk before you pull the trigger on the purchase).

Once you open shelf-stable oat milk, it needs to be refrigerated within two hours.

The other kind of oat milk sold in stores is refrigerated oat milk. You’ll find that right alongside traditional dairy products like milk, half-and-half, coffee creamer, etc.

This kind of oat milk will need to be refrigerated at all times—opened or unopened.

Refrigerated oat milk lasts between seven and ten days before it spoils. Again, though, check the expiration date before you use it.

how long will oat milk last

Storing Homemade Oat Milk

Maybe you have started to get into making your oat milk, though, and want to know how long that homemade batch is going to keep in the refrigerator.

As long as you have taken your time to blend and strain your oat milk and put it into an airtight jar (like a mason jar, for example), homemade oat milk will last 7 to 10 days before it spoils.

You should know this, though:

Unless you add emulsifiers (sometimes called stabilizers) to your homemade oat milk, the chances are pretty good that the concoction will separate as it sets up in your refrigerator.

That’s not a big deal as long as you don’t let the appearance of separated oat milk throw you off. Just shake the milk to mix it back together and you are good to go.

homemade oat milk shelf life

How Long Does Oat Milk Last?

Opened containers of oat milk will stay fresh and safe to drink for about a week and maybe up to 10 days or so – possibly even longer than that, depending on how fresh the oat milk is.

How Long Does Shelf Stable Oat Milk Last?

Unopened shelf-stable oat milk should last between six months and 12 months.

You might even be able to stretch that out to 18 months, depending on how fresh the oat milk was before it went through the shelf stabilization process.

As soon as you open up that shelf-stable of milk, though, you are right on the clock. You have between seven and ten days to use the oat milk before it goes bad.

How Long Does Refrigerated Oat Milk Last?

Refrigerated oat milk will last for a couple of weeks before you open it and then only a couple of days past that expiration date.

You’re pushing things if you try to use your refrigerated oat milk five or six days beyond that expiration date.

If you haven’t hit that expiration day window, you should be able to use your refrigerated oat milk within a week or so without any ill effects.

Just try not to push things to (or beyond) that expiration date. You won’t be happy with the results!

how long does oat milk last

Does Oat Milk Need to Be Refrigerated?

Oat milk needs to be refrigerated after being opened.

Oat milk's ingredients are natural and have a finite shelf life.

Shelf-stable oat milk gives you the longest amount of time before it needs to be pitched (or before they need to be refrigerated, even). But even shelf-stable oat milk has to be stored in the refrigerator after opening.

How Long Can Oat Milk Sit Out?

As a general rule of thumb, most oat milk manufacturers recommend that you refrigerate it within two or three hours of opening it.

Wait any longer than that (some people forget about oat milk and leave it set out overnight, even), and you run the risk of some pretty nasty harmful bacteria building up in the product.

Get your milk into the fridge ASAP!

How Long Can Oat Milk Sit Out

How to Tell if Oat Milk is Bad

The easiest way to tell if oat milk has gone bad is to sniff it.

If it smells funky, sour, off, or anything different from when it was new and fresh, the chances are pretty good that your oat milk has gone bad.

It’s essential to smell your oat milk as soon as you open it to get a feel for what the baseline should be.

Anything different probably means you should pitch the milk and get your hands on a new batch.

What Does Bad Oat Milk Smell Like?

One of the most interesting things about bad oat milk is that it has the smell that spoiled dairy milk has – a sour, off-putting, almost unbearably bitter, and pungent odor that you will recognize the first time it gets up into your nostrils.

If you smell your oat milk turning rancid, it’s time to pitch it down the drain.

Can You Drink Expired Oat Milk? 

Expired oat milk is safer to drink than expired dairy milk (but not much).

For starters, the flavor of oat milk that has passed will be pretty funky. That alone should stop you from drinking down a glass.

Secondly, while you’re not going to get the same amount of harmful bacteria and mold in oat milk that you would have with traditional milk, there will still be plenty of those “bad nasties” swimming around in this expired liquid.

As a general rule of thumb, do your level best to throw out oat milk the day after the expiration date has passed.

You’ll always be glad you did!

Can Bad Oat Milk Make You Sick?

You bet it can!

Bad oat milk can lead to food poisoning, intestinal inflammation, upset stomach, extreme gas buildups, and even vomiting and diarrhea.

Steer clear of bad oat milk.

About the Author

Kelly Donovan is a freelance writer. She enjoys helping people reach their wellness goals by educating them about how food plays a role in their health.