How Long Does Oat Milk Last?

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Oat milk is now the second most popular plant-based milk in the US, trailing only almond milk. US consumers bought almost $250 million worth of the stuff last year, up 208% from 2019. And that number is likely to increase in 2021.

If you’re interested in milk alternatives for whatever reason, you’ve likely noticed a variety of brands infiltrating store shelves and cafe menus. I love it as a coffee creamer and an ingredient in espresso drinks because it has a smooth texture and mild flavor that complements coffee wonderfully.

Once I started buying oat milk for my house, I started to wonder “how long does oat milk last?” It doesn’t show obvious signs of spoilage after a few days in my fridge, and different brands have different numbers for oat milk shelf life. Even more confusingly, some brands are shelf-stable while others need refrigeration.

With so much variety in the oat milk market, we’ll need to get back to basics before we can solve the oat milk expiration mystery.

What is Oat Milk?

At its most basic, oat milk is a combination of ground oats and water. You can even make it at home if you have a powerful blender and a nut milk bag! Like most people, however, I choose to buy my oat milk at the store and commercially made milk tends to have additives in it that can affect its shelf life.

Most oat milk brands, including popular ones like Silk and Oatly, use oils, thickeners, and stabilizers to create a creamy texture that more closely replicates dairy milk. Store-bought oat milk also tends to contain flavorings and sweeteners to make it delicious.

The presence or absence of oils, flavorings, and sweeteners can all affect your oat milk expiration date. Some brands also add preservatives that extend shelf life. Your best bet is to check the date on the carton and follow it.

Shelf Stable vs. Refrigerated Oat Milk

You may have noticed that some kinds of oat milk are stocked in the refrigerated section of the grocery store, while others sit on the shelves at room temperature. The difference between them has more to do with the packaging than the product itself.

Shelf-stable oat milk is packaged in a sterile container that completely shuts out air and contaminants. A sealed container can stay fresh for months or even up to a year, depending on what the manufacturer recommends.

This long shelf life is only applicable while the package stays sealed, however. After opening, shelf-stable oat milk should be refrigerated and consumed within a few days.

Refrigerated oat milk, on the other hand, is packaged in a carton or a bottle and must be kept refrigerated even before opening. It is generally fresh before the date printed on the label, or within around one week of opening, whichever comes first.

Some companies, including Oatly, sell both refrigerated and shelf-stable oat milk, so don’t assume you can leave your oat milk out at room temperature just because of the brand! A good rule of thumb is to store your oat milk the same way you found it at the supermarket.

How to Tell if Your Oat Milk is Bad

Although the safest bet is to follow the manufacturer guidelines for when to toss your oat milk, you can also check for signs of spoilage yourself. Like any other food product, oat milk tends to let you know when it’s not fit to drink.


This should be a no-brainer, but visible mold in the milk or on the container definitely means it’s time to trash your oat milk. Mold can contain toxins that will make you very sick.

Strange Taste or Smell

If you notice that the taste or odor of your oat milk has changed, it’s time to throw it away. Spoiled oat milk can exhibit a sour or funky odor and a bitter flavor.

Gas in Carton or Bottle

When food goes bad, sometimes the starch and sugar in the food start to ferment. This produces carbon dioxide gas, which can inflate a milk carton like a balloon. Bulging sides or a hissing noise upon opening are telltale signs that fermentation has occurred.

Change in Texture or Appearance

Oat milk should be smooth, creamy, and light in color. Chunks are definitely a big no-no. A darker color is also an indication that you should chuck your oat milk.

How Long Does Oat Milk Last

So when does oat milk go bad? In short, it’s complicated. The packaging, ingredients, and storage of the oat milk all can have an impact on the shelf life.

Some brands like Toats that don’t use stabilizers or preservatives need to be consumed in four days or less. Conversely, some shelf-stable brands can stay fresh unopened for up to a year. Here are some guidelines for different types of oat milk:


Homemade oat milk must be consumed within 2-3 days after making it. You also need to shake it before use at it contains no stabilizers.

Shelf Stable

Once, opened, shelf-stable oat milk needs to be refrigerated or consumed relatively quickly. Ideally, try to finish it in less than a week.


Generally, you should consume refrigerated oat milk less than two weeks after opening. This time window depends on the specific brand as well as on the sell-by date printed on the carton.

Exploring Healthy Food Options

So now that we’ve answered the question “how long does oat milk last” we can get to the fun part: using our oat milk in delicious recipes!

Oat milk is tremendously versatile and can be used for any purpose you would use dairy milk for. Grab a recipe, get in the kitchen, and have a good time! If you need some inspiration, this vegan moussaka is a great place to start.

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