Can I drink oat milk left out overnight?


Oat milk has become a popular plant-based milk alternative in recent years. Its creamy texture and natural sweetness make it a favorite for coffee, cereal, and more. But like any perishable food or beverage, oat milk does have some storage limitations. So what happens if you accidentally leave an opened carton of oat milk out on the counter overnight? Is it still safe to consume? Here is a comprehensive look at how long oat milk lasts at room temperature, how to tell if it has gone bad, and the safety issues surrounding consuming oat milk that has sat out overnight.

How Long Does Oat Milk Last at Room Temperature?

The shelf life of oat milk depends on several factors:

Factor Shelf Life
Unopened oat milk 7-10 days past the sell by date when refrigerated
Opened oat milk refrigerated 7-10 days
Oat milk at room temperature 2 hours

As you can see, oat milk has a very limited shelf life at room temperature. Dairy and plant-based milks can spoil quickly when left unrefrigerated due to the growth of bacteria. For optimal freshness and flavor, oat milk should be stored in the refrigerator after opening.

But what if you left out an opened carton of oat milk, say on your kitchen counter or dining table? At room temperature, opened oat milk will only last for about 2 hours before spoiling. Leaving it out any longer than this in an environment above 40°F poses safety risks.

How to Tell if Oat Milk Has Gone Bad

Oat milk that has been left out too long and spoiled will show the following signs:

– Sour smell
– Curdled texture; milk separates into watery whey and clumps
– Mold visible on surface
– Off-tastes like bitter, sour, or unpleasant flavores

If your oat milk exhibits any of these characteristics, it has spoiled and should be discarded. Safety experts advise against drinking or tasting oat milk that is past its prime.

Oat milk that has just barely expired but has been refrigerated the whole time may still smell and taste normal. But oat milk left out overnight will show more dramatic signs of spoilage like clumping, separation, or the growth of visible mold.

Is it Safe to Drink Oat Milk Left Out Overnight?

Dairy and plant-based milks should never be left out at room temperature for more than 2 hours, according to food safety recommendations. If oat milk sits out overnight (8-12 hours), it enters the “danger zone” of 40-140°F when bacteria can multiply rapidly.

Consuming oat milk that has been left unrefrigerated for more than 2 hours poses some risks:

Risk Explanation
Food poisoning Bacteria like Bacillus cereus, Staphylococcus aureus, Salmonella, and E. coli can grow and produce toxins that cause vomiting and diarrhea.
Mold exposure Oat milk may develop visible mold from Penicillium, Aspergillus, and other genera that release allergenic spores.
Off-flavors Spoiled oat milk will taste unpleasant due to microbial growth and chemical changes.

So while an accidental sip of oat milk left out overnight may not make you violently ill, it is not recommended from a food safety standpoint. The bacteria count could be high enough to cause foodborne illness, especially in those with weakened immune systems. Babies, elderly people, pregnant women, and those with chronic illnesses are at higher risk for complications.

How to Store Oat Milk Properly

To get the most shelf life out of your oat milk and avoid safety issues, follow these storage guidelines:

– Refrigerate oat milk after opening. Keep it as cold as possible at 40°F or below.
– Drink refrigerated oat milk within 7-10 days of opening. Write the date you opened it on the carton.
– Keep unopened, shelf-stable oat milk in a cool, dry pantry. Drink within 5-7 days of opening.
– Never leave oat milk out for more than 2 hours at room temperature.
– Keep opened oat milk in the back of the fridge where it is coldest.
– Check for expiration dates and don’t drink oat milk past its sell by date.
– Check refrigerated oat milk for signs of spoilage like smell, appearance, and texture before drinking.

Following proper refrigerated storage will keep your oat milk fresh and safe to drink. Discard any oat milk you suspect has been left out too long and may be contaminated or spoiled. Don’t take risks with perishable dairy-free milks and stick to the 2 hour room temperature rule.

Can Spoiled Oat Milk Make You Sick?

Yes, consuming oat milk that has been left unrefrigerated for too long can make you sick. Here’s a look at how:

Bacteria Growth

Bacteria like Listeria, Salmonella, E. coli, and Staphylococcus can grow in oat milk left out overnight, producing toxic byproducts that cause illness. Symptoms usually appear 12-72 hours after ingesting contaminated milk and include:

– Nausea, vomiting, diarrhea
– Fever, chills, body aches
– Abdominal pain and cramping
– Headache

Mold Contamination

If oat milk develops visible mold from being left out too long, it may contain dangerous mycotoxins. These chemicals can cause allergic reactions or even liver damage if enough contaminated milk is consumed.

Chemical Changes

Proteins and fats in oat milk degrade faster at warm temperatures. Rancid fats and proteins can irritate the stomach lining and cause vomiting, diarrhea, and cramps.

So while drinking oat milk that’s over 2 hours old may not make you acutely ill every time, it’s simply not worth the risk. Stick to refrigerated storage and pay attention to expiration dates to keep your oat milk safe. Discard any that you think may be compromised.

Does Spoiled Oat Milk Taste Bad?

Yes, oat milk that has spoiled due to improper storage usually tastes bad. The high bacterial growth and chemical changes create off-flavors and odors.

Here are some of the unpleasant tastes and smells you may notice in bad oat milk:

– Sour, buttermilk-like taste
– Sharp, vinegar flavor
– Bitter taste
– Moldy, musty taste
– Rancid, unpleasant aftertaste
– Rotten egg odor
– Stale cardboard flavor

The clumpy, curdled texture of spoiled oat milk also makes it very unpalatable. Consuming rancid and bitter oat milk is not harmful in small amounts. But the unpleasant taste and smell should deter you from drinking milk that is clearly past its prime.

Can You Make Oat Milk Safe to Drink Again?

Unfortunately, there is no way to make oat milk safe to consume again once it has spoiled from sitting out too long:

– Boiling or microwaving oat milk will not kill the bacteria or mold that has developed.
– Stirring or remixing curdled oat milk does not reverse the spoilage.
– Cooling or chilling sour oat milk does not restore its safety or quality.

Once opened oat milk exceeds the 2 hour room temperature limit, it’s best to discard it. The bacteria levels may be high enough to tolerate reheating. And the unpleasant flavors persist even if cooled again. Do not take chances with oat milk that has been left out overnight.

The bottom line? Stick to safe refrigerator storage times and discard any oat milk that you suspect has spoiled, rather than trying to salvage milk that has been improperly stored. It’s simply not worth the risk.


Oat milk is a nutritious, tasty milk alternative, but it does carry a risk of foodborne illness if left out at room temperature too long. Drinking oat milk that has been left out on the counter overnight is dangerous, as bacteria can multiply to unsafe levels after 2 hours.

Look for signs of spoilage like curdling, off-smells, mold growth, and strange textures. Oat milk that sits out all night will taste unpleasant as well, with a sour, rancid, or bitter flavor. Do not drink oat milk if you suspect it is spoiled. Remember to always refrigerate opened oat milk within 2 hours and discard any milk that exceeds this time limit at room temperature. Proper storage and handling will keep your oat milk safe and your risk of getting sick low.

Similar Posts

Leave a Reply

Your email address will not be published. Required fields are marked *