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How Long Does Oat Milk Last? Does It Go Bad?

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When it comes to alternative milk options, the choice in the grocery store is vast! The surge in dairy-free milk options has led to many of us trying different versions, and oat milk is becoming a popular favorite.

How long does oat milk last? And does it go bad? Oat milk does go bad over time, particularly if kept in the wrong conditions. Shelf-stable oat milk can be stored for up to 9 months in a cool dry place, whereas refrigerated oat milk must always be kept chilled. Once opened, oat milk lasts between 4-7 days if kept in the refrigerator. 

Want to make sure you always have a fresh supply of oat milk in the pantry? We have got all the answers and more for you!

We will take a look at how long oat milk lasts and give you some tips on the best way to store this delicious milk alternative.

What Is Oat Milk?

If you look at a bag of whole oats, it can be difficult to imagine how they could be turned into milk! However, through some clever processing, they can be used to create dairy-free milk that is deliciously rich and creamy.

To create this milk, oats are soaked in water then blended into a pulp. This is strained through a fine material such as cheesecloth, or a nut milk bag. The strained liquid is the oat milk, and the oat pulp remains inside the bag.

The flavor of oat milk is surprisingly similar to cows’ milk, with a slight hint of oats. It is slightly sweeter than dairy milk, making it a popular addition to hot drinks.

One of the great advantages of oat milk is that it is packed full of nutritional goodness. The range of vitamins and minerals in oat milk includes manganese, phosphorus, folates, zinc, selenium, iron, and copper. 

Oat milk is also very similar in terms of calories to dairy milk but is much lower in sugar. It is also richer in fiber, whereas cow’s milk contains none.

When it comes to protein, oat milk is lower in protein than dairy milk. However, it does contain more protein than most other types of non-dairy milk.

The great thing about oat milk is that it is suitable for anyone who is allergic or intolerant to dairy or nuts.

Oats are also gluten-free but check the packaging carefully as some oat milk varieties are processed in factories that also process grains containing gluten.

Does Oat Milk Need To Be Refrigerated?

When purchased from the store, oat milk comes in 2 different forms: shelf-stable and refrigerated.

Shelf-stable oat milk has been packaged using a method that eliminates all unwanted microorganisms.

This means that, until the carton is opened, the milk is completely stable and should not spoil. Shelf-stable oat milk does not need to be stored in the refrigerator until it has been opened.

However, you still need to keep your carton of oat milk in the best possible conditions.

A cool shelf in your pantry or kitchen cupboard will help to keep the milk at a consistent temperature. The advantage of shelf-stable oat milk is that it has a very long shelf life.

Refrigerated oat milk is considered to be a fresher product, and will not have been processed to eliminate microorganisms.

This means it must be stored in the refrigerator at all times, before and after opening. Refrigerated oat milk has a much shorter shelf life than its shelf-stable counterpart.

If you are not sure about how you should be storing your oat milk, have a look at where you buy it from in the store!

If it was sat on the shelf, then it can be stored on your pantry shelves. If it was in the chilled foods section, then it needs to go in the refrigerator—simple!

Whatever type of oat milk you have, it must be stored in the refrigerator once opened. And although we all tend to keep our milk in the fridge door, this is actually the worst place for it!

The door of the refrigerator is subject to much higher temperature fluctuations than the shelves of the fridge.

It’s not the end of the world if you keep your oat milk in the door, but it may not stay fresh for quite as long. If possible, keep your oat milk on one of the refrigerator shelves instead.

Does Oat Milk Go Bad?

While oat milk is relatively stable and will stay fresh for longer than dairy milk, it definitely can go bad! The thing to remember is that, unlike milk, it will start to deteriorate gradually rather than turning bad suddenly.

Oat milk can be stored for a long time; however, you do not want to risk drinking oat milk that has gone bad! As well as risking an unpleasant stomach upset, oat milk that has gone bad will not taste at all pleasant.

A carton of oat milk that has been opened will turn bad much more quickly than an unopened one. However, even unopened oat milk can turn bad, whether it is the refrigerator kind or the shelf-stable version.

So, if your oat milk has been open for a few days, or is past its use-by date, it is vital to check it carefully to make sure that it is still safe to drink.

How To Tell When Oat Milk Has Gone Bad

Here are the best ways to check if your oat milk has gone bad:


Often, the first sign of deterioration of oat milk you will notice is a change in the texture. It will start to go lumpy, with the remaining milk taking on a watery appearance. Bad oat milk can also appear slimy.

If your oat milk is thicker than usual, has a slimy texture, or you see lumps, then throw it out. These are all signs that it has started to turn bad.


The tricky thing with non-dairy milk is that the smell does not change much until it is really past its best. So, if your oat milk smells the same as normal, this does not mean that it is not starting to deteriorate!

However, if your oat milk has a sour smell, it has definitely gone bad and should be discarded.

Color & Appearance

The normal color of oat milk is creamy-white. If the color is not as you would expect it, don’t risk drinking it.

If the oat milk is inside a clear plastic bottle, look carefully for any patches of mold on the surface of the milk or inside of the bottle.

This can be difficult to check if your oat milk is in a carton unless you pour out the milk and cut the carton open.


If your oat milk has passed the first three tests, try giving it a taste. A small amount of bad oat milk is unlikely to cause any harm, but only take a tiny sip just in case!

If the flavor is not the same as when you first opened the carton, it may have started to go bad.

If it tastes, smells, and looks exactly like fresh milk, then it is most likely perfectly safe to drink!

However, if it has been open for much longer than the manufacturers recommend, then we would advise that you don’t take the risk and open a fresh carton of oat milk instead.

How Long Does Oat Milk Last In The Pantry?

When you buy a shelf-stable carton of oat milk, it will have an expiration or best-before date printed on it. However, this date is purely a recommendation from the manufacturers, and the oat milk may be perfectly safe to drink after this time.

Shelf-stable oat milk normally has a reasonably long shelf-life, normally at least 9 months from the production date.

This gives you a reasonable chance of consuming it well before the best-before date. But what happens if you’ve found a carton lurking at the back of the shelf which has gone beyond this date—is it OK to drink?

If kept in the right conditions, shelf-stable oat milk will normally last for at least a few months beyond the best-before date. 

The best way to ensure that your carton of oat milk does not deteriorate is to keep it in a cool, dark, dry place, away from direct sunlight and extremes of temperature.

As with anything past its best-before date, check it carefully to ensure it hasn’t gone bad before consuming! We would recommend that older oat milk be used as soon as possible once it has been opened.

How Long Does Oat Milk Last After Opening?

Once a carton of oat milk has been opened, it will start to deteriorate. This is the same whether you are using shelf-stable oat milk or refrigerated.

Your oat milk will clearly state on the label how quickly it should be consumed once open.

This is normally around 4 days, but might be less for refrigerated oat milk. The reason for this is that refrigerated oat milk has not been purified of bacteria, whereas shelf-stable oat milk has.

As soon as you open a carton or bottle of oat milk, bacteria can enter the container and will start to colonize the milk. However, the speed at which they can multiply depends on the temperature that the milk is stored.

You may be able to extend the life of an open container of oat milk so that it is safe to consume for up to 7 days.

To do this you must keep it refrigerated at all times, and keep the lid tightly closed to prevent contamination. However, check it carefully each time you use it, in case it has started to turn bad.

To enjoy your oat milk at its absolute best, consume it within 2-3 days of opening. Even if oat milk does not go bad, the flavor starts to change after a couple of days once the carton has been opened.

It will still be safe to drink for 1-2 days after this, but the flavor will not be as fresh.

Can Oat Milk Be Frozen?

If you’ve opened a carton of oat milk and think you may not use it before it goes bad, you might be wondering if you can freeze it to preserve it for longer?

The good news is that yes, you can!

Freezing is a great way to store oat milk and can save you the trauma of having to pour away half a carton of oat milk that has gone past its best.

However, the texture of oat milk does change slightly once it has been frozen and thawed. It will lose that lovely smooth texture and become grainier.

This means that oat milk that has been frozen might not be the most appetizing for pouring on cereal or adding to hot drinks, but it is perfectly good for use as a baking and cooking ingredient.

It is a good idea to pour your oat milk into containers that hold the right amount for cooking, so you do not need to defrost it all at once.

For example, if your favorite pancake recipe requires 2 cups of oat milk, then freeze this amount in each container.

As with anything you are adding to the freezer, keep your oat milk in an airtight container to prevent freezer burn. Label the container carefully with the contents and date it was frozen.

Oat milk can be stored for up to 3 months in the freezer before it starts to deteriorate.

What Is The Best Way To Store Oat Milk?

So, in summary, here are the best ways to store oat milk in all its different forms:

  • Unopened shelf-stable oat milk should be stored in a cool, dark, dry place, away from direct sunlight and extreme temperatures. Once opened, shelf-stable oat milk should be stored in the fridge.
  • Refrigerator oat milk should be stored in the fridge, whether it is open or unopened.
  • Both types of oat milk will keep for 4-7 days in the refrigerator once opened.
  • If you are not going to use your oat milk within this time, it can be frozen for up to 3 months. Frozen oat milk can be used for cooking and baking, but will be too grainy for hot drinks and cereals.

Related Questions

Now that we’ve gone over how to properly store oat milk, let’s take a look at a few related questions on the subject!

How long does oat creamer last?

Oat creamer is a health and dairy-free option if you are looking for an indulgent creamer for your coffee. But once you’ve opened a container of oat creamer, how long does it last?

To keep it at its best once opened, oat creamer should be stored in the refrigerator in a sealed container. It is at its best when consumed within 5-7 days, although it could last for up to 14 days under the right conditions.

If the oat creamer has a sour smell or has started to turn yellow in color, then it has gone bad and should not be consumed.

Can you make oat milk at home?

If your carton of oat milk has gone bad, is it possible to whip up a batch of oat milk at home?

This dairy-free milk is simply a fine blend of oats and water, that is strained to separate the milk from the oats. So yes, you can definitely make oat milk at home!

To make oat milk, add 1 cup of rolled oats and 4 cups of water to your blender bowl. Leave to stand for 5 minutes, then blend on high speed for 1 minute.

Strain this mixture through a fine material such as muslin, or a nut milk bag. Voila, you have oat milk! Store your homemade oat milk in the refrigerator and consume it within 5 days.

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