How Long Can Oat Milk Sit Out? (Explained!)

As more and more people are concerned about our environment every day, Oat Milk has lately become nearly as popular as the classic milk we get from cows. You can buy it basically anywhere nowadays, and even your grandma probably knows what oat milk is.

That being said, though, it doesn’t mean many people would know a hell lot about it. Quite the contrary, the vast majority of people still don’t understand how oat milk is made, nor do they know the answer to this fundamental question:

How long can oat milk sit out? As the official safety guidelines by USDA say, an opened container of oat milk cannot sit out for more than two hours. The reason is that bacteria grow exceptionally fast at temperatures between 40 °F – 140 °F, which means drinking oat milk left out for longer than two hours might very likely be dangerous.

So that’s it, now you know the answer, right? Well, not really, since because this topic is a bit complicated, there’s actually much more to be told. But don’t worry, everything you need to know will be uncovered in this article.

So let’s not waste any more time and just get started!

How Long Can Oat Milk Sit OutPin

Does oat milk need to be refrigerated?

Although, in some cases, oat milk doesn’t require refrigeration, usually you’ll still have to put it into the fridge. While oat milk that is sold airtight sealed can be stored even outside the fridge, the rest always has to be refrigerated. 

Additionally, after you open your oat milk, you always have to put it into the fridge, no matter what type it is – once the sealing is broken, it doesn’t play its role correctly anymore, meaning the oat milk now requires refrigeration.

How long can oat milk sit out unopened?

Believe it or not, shelf-stable oat milk (the one with airtight sealed packaging) can sit out unopened for even a few months in some cases and still be good to go! To put it simply, shelf-stable oat milk indeed is shelf-stable, and you, therefore, don’t have to worry about putting it into the fridge.

But on the other hand, there’s also the kind of oat milk that can’t last on its own. So that one should be refrigerated literally always – according to the USDA, refrigerated oat milk cannot sit out for any more than two hours if you want to be sure it’s safe to drink.

How long can oat milk sit out after opening?

As the United States Department of Agriculture says, no perishable food should ever sit out for more than two hours if you want to be entirely sure that it’s safe to eat. Hence, oat milk sit out for no more than two hours after opening,

Is oat milk still good if you leave it out?

Because the vast majority of oat milk comes in airtight sealed containers, usually, oat milk is still good if you leave it out. However, some kinds of oat milk should be refrigerated, and these are not good to go when they’re left out for more than two hours.

And the same goes for every opened pack of oat milk, no matter its type – once you open it, you always have to store it in the fridge because an already opened pack of oat milk isn’t still good if you leave it out of the fridge.

Can oat milk be left out overnight?

In most cases, oat milk can be left out overnight – since oat milk is usually sold in airtight sealed containers, it most often doesn’t have to be in the fridge at all, meaning leaving it out overnight isn’t a problem.

With that in mind, though, we’ve got to mention that some kinds of oat milk should, on the contrary, be in the fridge always. And leaving this kind of oat milk out overnight can very likely make it dangerous to drink.

And even besides that, all kinds of oat milk have to be refrigerated after opening, because once opened, oat milk can spoil in a matter of two hours at room temperature. Hence, an already opened pack of oat milk cannot be left out overnight. 

How long can oat milk sit out in coffee?

According to the USDA, perishable food, including oat milk, can sit out for only two hours to be entirely safe for use. Since bacteria grow extremely quickly at room temperatures, chances are your oat milk will be dangerous to drink after being left out for a longer time.

And that goes even for oat milk that was put into the coffee – therefore, oat milk can sit out in coffee for no more than two hours if you want to be sure that it’s still safe to drink it.

How do you know if oat milk has gone bad?

Believe it or not, there are not many easier tasks than telling bad oat milk from the good one. To know if your oat milk has gone bad, you just have to take a good look, a good sniff and most conveniently also taste a bit of it.

If you saw, smelled, or tasted anything weird, it means that the oat milk has already gone bad; otherwise, it’s good to go. Yeah, it is simple as that!

What does bad oat milk taste like?

However, you might not be sure about what exactly does “weird” means. So what is the taste of bad oat milk? Look for acidity – bad oat milk tastes much, much sourer than normally, so throw it away as soon as possible when the milk is acrid.

What does bad oat milk smell like?

And it is nearly the same with the smell because when oat milk spoils, it develops a weird odor resembling its taste a lot. So bad oat milk simply smells bitter and sour, and not like sweet nuts like usually.

How do you keep oat milk fresh?

We’ve mentioned above that there are a lot of kinds of oat milk that don’t require refrigeration before opening because they’re airtightly sealed. Therefore, airtight sealed containers seem like the best choice while deciding how to store your oat milk.

So to keep oat milk as fresh as possible, firstly pack it into some airtight sealed containers (if it already is, you can skip this part). After that, put the milk into the fridge, making it last even longer.

What happens after drinking spoiled oat milk?

Just like with pretty much any other food, drinking oat milk that has already turned bad may cause some harm. After drinking spoiled oat milk, you might not unlikely experience some classic symptoms of food poisoning like vomiting or diarrhea.


In most cases, oat milk is sold in airtight sealed containers and therefore doesn’t require refrigeration before opening. However, if you bought your oat milk in the refrigerated section, it is not able to stay good on its own – this kind of oat milk can sit out for only two hours before being dangerous to eat, meaning you have to make sure it’s in the fridge all the time.

And the same goes for oat milk you’ve already opened as well – since opening it breaks the packaging, opened oat milk has to be always refrigerated because it cannot be left out of the fridge for more than two hours either, no matters its kind.

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Image credits – Canva

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