Skip to Content

How can you tell if oat milk has gone bad?

Sharing is caring!

*This post may contain affiliate links. Please see my disclosure to learn more.

Oat milk is one of the most popular dairy free beverage choices for people of all ages. You may question whether or not oat milk can expire and how do you know if oat milk has spoiled.

Whether you drink oat milk everyday, or purchase bulk quantities, if you do not use oat milk regularly then you will have to store unopened containers in a cool, dry and dark area. When stored properly, unopened oat milk has a shelf life that can easily last six to nine months.

How do i know when oat milk is bad? When the seal is broken and the container has been opened for the first time, then oat milk is considered a perishable food that can quickly turn rancid. It should be consumed within 4 to 7 days, but it may even last up to 10 days. 

The date labels are recommended guidelines, but your sense of sight, smell and taste will ultimately tell you if the oat milk has gone bad.

The important concern is how do you know if oat milk has already gone bad or expired? If you have questions about the storage of oat milk and these things are bothersome, then you have come to the right place and this article will help.

What Is Oat Milk?

Oat milk is a beverage that is made by blending oats with water. The liquid is strained to separate the residual pulp from the cream liquid left behind looks like cow’s milk, which is why it’s called oat milk.

The dairy free milk has gained popularity in recent years because it is vegan, lactose free, nut free, soy free and gluten free. That is because oat milk benefits include being a perfect substitute for anyone that experiences issues with lactose intolerance, celiac disease or allergic to nuts.

Oat Milk Storage

If you want to store unopened oat milk, then no rocket science degree is required. In the case of sealed or unopened oat milk containers, the beverage is shelf stable and can be kept in a cool and dry place, it will last long without any problems. 

Placing the sealed oat milk containers in a cupboard or dry storage area is a great choice, a fridge also works well but that may not be the most economical or efficient use cold storage space. 

You can not store sealed oat milk containers in the freezer. Water is the primary ingredient in oat milk, and water expands as it freezes, therefore the packaging will explode and oat milk will be all over the place.

If you have a separate pantry in your kitchen or downstairs basement area, then it is recommended to store bulk oat milk for the long term. If the room temperature is stable, then you should be able to maintain quality and freshness of the sealed containers for as long as nine months, and possibly much longer.

Once the seal has been broken and the container is opened, oat milk is perishable and no longer shelf stable. The package must be airtight to reduce export to air and moisture, and transferred to the refrigerator where the oat milk will stay fresh for up to 7 days.

As you can see, oat milk may go bad and spoil, but you can maintain quality and freshness by extending the shelf life when properly stored.

Oat Milk Date Labels

Best before, use by, sell by and best by are expiration date labels that confuse consumers with unclear information. So, how do you determine if the date label on your oat milk is correct?

In fact, a majority of manufacture date labels are not based on exact science.

To be honest, date labeling is provided to help consumers and retailers decide when food is of best quality, but label dating is not an exact science and does not accurately determine food safety. When it comes to oat yogurt, a cultured oat milk product, it can last for weeks beyond the expiration date without any problems.

Once the packaging has been opened, the freshness of the product is compromised after being exposed to air. The clock is ticking and the oat milk need to be consumed sooner rather than later.

Unopened oat milk shelf life

Packaged oat milk is shelf stable, and does not require refrigeration until the seal has been broken. The shelf life for packaged oat milk is about 9 months, but this is just a recommended date label.

Does oat milk expire? When stored in a cool, dark and dry area, unopened oat milk can last three to five years without any problems. 

If the container is sealed, there is no risk of bacteria exposure, mold and spoilage.

How long is oat milk good for after best by date? The best by date is just a manufacturer recommendation for quality and freshness, it is not a determination for the exact expiration date. 

Use your best judgement of sight, smell and taste to determine if the oat milk is still good after the best by date.

Does oat milk go bad if not opened? If you have any concerns about the shelf life of unopened oat milk, your senses should be able to make the final determination. 

A change in color, smell, taste and texture will help you determine whether or not the unopened oat milk has gone bad.

Does oat milk go bad if you leave it out? Unopened oat milk is sold in the dry goods area of the supermarket, and not kept in cold storage. 

Opened oat milk will go bad if you leave it out. Manufacturer guidelines recommend that oat milk be refrigerated after opening and used within 7 to 10 days.

How Long Does Opened Oat Milk Last?

Unopened oat milk is shelf stable, however once the package has been opened the oat milk becomes perishable and must be kept under refrigeration. 

How long can you leave oat milk in the fridge? Once the oat milk has been opened, it is best when consumed within 4 to 7 days, however it may last for up to 10 days

It’s important to refrigerate oat milk and oat creamer immediately after opening and make sure the container is sealed airtight.

When determining how long opened oat milk lasts, key factors are time, temperature and air exposure.

  • Time: If the container was opened and left at room temperature for a few hours, then the oat milk may spoil much faster. According to the USDA temperature danger zone guidelines, perishable food items need to be refrigerated or frozen within 2 hours. After you use the oat milk, place it back in the fridge so it stays cold and fresh.
  • Temperature: When oat milk is left out on a hot summer day, then the chance of spoilage is much greater than being left out in the cold of winter. The ambient room temperature will have an effect of the longevity of the oat milk storage, even if you place in into the fridge after an hour or two. Store it in the fridge to keep it as fresh as possible. 
  • Air exposure: It is important to minimize contact with air as that increases the risk of the oat milk going bad. For optimal storage conditions, an airtight container should be used with minimal amount of air left inside the vessel, otherwise, it will spoil quickly.. Most manufactured oat milk brands come in an airtight container, so this shouldn’t be an issue.

Can you drink oat milk after 7 days? Yes, oat milk typically lasts between 7 to 10 days after opening when properly stored in the refrigerator. 

The key to extending the length of time is minimized exposure to air, temperature extremes and time outside cold storage. 

How long can you drink oat milk after the expiration date? If stored properly, below 40 degree Fahrenheit, then oat milk may even last up to 14 days.

Manufacturer recommendations state 7-10 days on the packaging, but your senses will help to determine if something is wrong before or after that length of time. Changes in color and flavor will be a clear indication that the oat milk has past its prime.

How do know if oat milk has expired?

If date labels are not a concrete determination examined as fact, then what are the best ways to decide if your oat milk has expired? Ultimately, we recommend relying on your senses to determine the freshness and quality of the beverage. 

Look and smell, then taste to evaluate whether the oat milk is still safe to consume. Oat milk should have a sweet nutty smell, look beige in color, have a smooth consistency without lumps and taste neutral without any off-putting, bitter or strong foul flavors. 

It’s common to see oat milk separating, so that is not a detrimental factor. Give the container a good shake and the oat milk should emulsify back together.

Discoloration: Fresh oat milk has a milky, light brown or cream-like color. Any difference in color could result from the growth of mold inside the storage container. Do not proceed any further and the milk should be flushed.

Mold: Though it generally takes longer time, mold can grow on liquid. When the container is opened, airborne spores can enter. Given a long enough time period, the spores can multiply and visually appear on the surface. If there is any mold, discard immediately.

Off-putting smell: When oat milk is poorly stored or kept years beyond the expiration date, it may develop an off-putting smell that no longer resembles a sweet nutty aroma, but rather a pungent, sour or bitter odor.

How do you tell if oat milk has gone bad

Drinking Bad Oat Milk

Many commercial oat milk packages come with ‘best if used by’ date printed on the container. However, this does determine a particular date or month the the beverage will go bad.

Unopened oat milk has a long lifespan. If the containers are properly stored at room temperature, then they will not go bad after the expiration date.

Can expired oat milk make you sick? The idea of an expiry date is a common misconception. 

In general, expired oat milk can still be good for months if not years beyond the label date marked on the packaging. Therefore, it is possible that drinking expired oat milk will not be harmful at all.

What does bad oat milk taste like? Expired oat milk can be safe to drink, but if you notice any kinds of molds, different colors or off-putting smells, then do not to consume.

Use your senses to determine the freshness, quality and safety of the expired oat milk. If something looks or smells off, then don’t even take a chance.

Can you get sick from expired oat milk? Expired oat milk and spoiled oat milk are completely different things. Just because the ‘best by’ date has past doesn’t necessarily mean that the oat milk is bad.

What happens if you drank spoiled oat milk?

Yes, you can consume expired oat milk, however you can get sick from drinking spoiled oat milk. Bad oat milk can cause food poisoning, which may lead to intestinal inflammation, vomiting or diarrhea.

Furthermore, opened oat milk is exposed to oxidation that can cause rancidity. This means that the liquid is exposed to air, which brings bacteria, spores and microbial growth. 

When oat milk is no longer fresh, then it will become less nutritious as the vitamins and minerals are degraded over time. Though you can consume expired oat milk without any concern, it is not advisable to ingest spoiled oat milk.

What can you do with expired oat milk?

If you have old or expired oat milk, then you should not rush to throw it out. 

It is an automatic assumption that because the use by date has past, the beverage has expired and should be thrown out. But, you should avoid the urge. 

You can use old oat milk for body care to add vitamins and minerals that will make your skin smooth. Body scrubs, soap bars and bath bombs are easy to make with old oat milk that has seen better days.

Oat milk has been used to hydrate skin, as a natural remedy for acne and also to alleviate dry and irritated skin. 

Heat the oat milk in a pot over the stovetop and the liquid will thicken up into a smooth paste. Allow it to cool before applying it to the affected areas, you will notice a soothing effect the will heal open pores and inflamed areas.

Apply the thickened oat milk paste as a face mask and let sit for 15 minutes before washing off.

Oat milk also works well as a soft and gentle moisturizer to neutralize pet odor. Has your dog ever been skunked? Trust me from experience! 

Make crafts for young kids. If your kids are easily amused, then you can turn the old oat milkinto paper mache projects.

After cooking the oat milk, the starch will thicken similar to the traditional paper mache projects with newspaper, water and flour. Add a paint brush and some colors if you want to expand on the creativity.

Expired Oat Milk: Final Thoughts

Oat milk is a healthy beverage choice enjoyed by many. It goes well with granola, baked goods, overnight oats, smoothies and more.

However, they’re some concerns over oat milk going bad and if you can you still drink expired oat milk. 

Easily extend the shelf life of not opened oat milk by following the recommended storage tips. Unopened oat milk must be stored in a cool, dry and dark area to maintain freshness for a long term. 

Package oat milk is labeled with a shelf life of 9 months, but that date label is purely a recommendation. When stored effectively, unopened oat milk can easily last three to five years

If oat milk has past their expiration date, they are most likely safe to consume. Check for concerning factors such as discoloration, mold, off-putting smell and critters

Once the seal is broken for the first time, oat milk must go into the fridge right away. Time, temperature and exposure to air can cause the oat milk to go rancid much quicker.

In general, opened oat milk will stay fresh between 4 to 7 days, but may last up to 10 days when refrigerated properly.

If the quality of the oat milk has come into question or been compromised in any way, then do not consume the beverage. However, it may not be necessary to throw away the liquid as it might possibly be used for body care, kids crafts and to counteract bad odors.

Sharing is caring!


Sunday 17th of July 2022

Hi, I am very concerned. I was not aware at how fast oat milk goes bad, nor that there was black mold growing in the bottle. I drank some of it today, and it seemed funny and it was the last of the container. I opened the container and there were green and black spots growing on the sides of it. I don't know if I drank some of the mold this morning, should I contact a doctor?


Monday 18th of July 2022

I would contact a physician and see what they advise for this specific situation. Wishing you the best!


Sunday 1st of May 2022

I have some shelf stable Chobani plain oat milk, but upon looking at the date on the packaging, it is 2 months past. As this is shelf stable, has not been opened, and stored in a dark place, would this still be fine to drink?


Wednesday 4th of May 2022

Hello Sandy, thanks for sharing. I would open the container, give it a smell and determine if it is sour. Then I would look at it, and if nothing seemed out of the ordinary, I would probably consume a small amount to give a quick try. If it passes the smell, look and taste test, then you should be good to go.


Friday 7th of January 2022

Hi. Just opened a container of oat milk and the seal beneath the cap was opened. Pouring out some of the milk, it was a darker color than I had previously seen.

On Planet oat, does the seal open when you remove the cap and, should I be concerned about the color (almost like milk chocolate)



Monday 2nd of May 2022

@Phil, I noticed the same thing with the Planet Oat milk in cartons. The inner seal is broken on every one but the outer seal is intact.I decided to put it on my cereal anyway and it was ok.


Friday 7th of January 2022

Hello Phil, thanks for reaching out. The top of the carton says, "Do not use if seal under cap is broken." Therefore, I would throw it out because it seems like that container has been compromised. Furthermore, it should not look dark like milk chocolate unless you purchased a chocolate flavored beverage.


Monday 4th of October 2021

I've got some oat milk in the fridge that has been open for awhile. It now has a tangy flavor, kinda like its begun to ferment. Is this possible? The thing is, I actually like this tangy oat milk better than when it was fresh/just opened. So far, it hasn't made me sick. I'll keep drinking it until it looks or tastes bad unless I experience any stomach upset.


Tuesday 5th of October 2021

Hello Kat, yes it is absolutely possible for the oat milk to ferment and become slightly tangy. This happens because grains will ferment when exposed to liquids such as water, similar to the process for making beer. It should be safe to drink the fermented oat milk as long as it does not mold or get exposed to other types of bacteria. A slightly sour smell is totally different that a spoiled and off-putting odor. Enjoy while you still can, Joshua


Friday 2nd of July 2021

Hello, thanks for all the great information. I'm wondering though about the safety of unopened shelf stable oat milk that has been exposed to high ambient temperatures? Having just gone through the severe heatwave here in Portland, Oregon in an apartment with no A/C - so inside temps in triple digits for about 3 days, so much shelf stable food already spoiled... Do the tetrapacks offer any insulation that protects from these prolonged high temps or is the oat milk just shelf stable at room temperature and slightly above? Any guidance most appreciated, thanks so much, take care.


Saturday 3rd of July 2021

Hello K, thanks for reaching out. I am definitely not a packaging expert, but my guess is that it should all be fine. First of all, I would check one or two unopened containers with basic observations like look, smell then taste a couple drops. If you don't see anything off visually, smell foul odors or taste sourness, then it should be fine. In a sealed environment, the unopened oat milk should not really be exposed to harmful bacterias. If the container is at all punctured because it expanded and contracted due to heat, then it is definitely no good. Although the expiration date is just a recommendation, I would assume that the longevity would be compromised so it might be best to use them up sooner rather than later. Hope this answer helps, don't hesitate to reach out with any further thoughts. Best, Joshua