How Long Can Milk Sit Out?

Milk is one of the most commonly bought food items in the world. Everyone knows that milk needs to stay in a cool, refrigerated state to maintain its shelf life.

If it stays outside its desired cold temperature for too long, it will result in growth of bacteria and will curdle. 

How Long Can Milk Sit Out?

The last thing you want is to see that you accidentally left a bottle of milk out on the kitchen counter for several hours. If you open it up and it smells acrid, there’s a high chance that the milk has gone off and cannot be saved. 

So, how long can milk sit out? The short answer is that you shouldn’t leave milk to sit out longer than two hours.

Any longer than that, and you risk the chance of bacteria growing inside the milk. 

Here is everything you need to know about how long milk can stay outside the refrigerator, and how to prolong the shelf life of milk. 

How Long Can Milk Sit Out?

The general rule of thumb is that milk should not be left out of the refrigerator for longer than two hours. Two hours is the absolute maximum time milk should be left to sit out – any longer than this, and bacteria will begin to grow. 

However, in summer when the temperature reaches 90 degrees Fahrenheit and higher, you shouldn’t leave the milk out for longer than one hour.

This is because bacteria thrives in heat, so the warmer it is, the less amount of time your milk should be left out. 

There is a “danger zone” in the world of food safety, which indicates a temperature zone where bacteria thrives. This danger zone sits between 40 and 140 degrees Fahrenheit.

This temperature zone provides bacteria with all the temperature they need to multiply and contaminate the food. 

It’s normal to consume small amounts of bad bacteria without becoming sick. As humans, our immune systems are used to bacteria, and continue to strengthen when we consume small, safe amounts.

This is why there is a two-hour rule to leave milk out of the refrigerator. 

Once the two hours are up, however, the milk should not be consumed. The longer the milk is left out of the refrigerator, the more bacteria will contaminate it.

If you consume the milk after it’s been left out for two hours, your chances of getting sick are much higher. 

What Happens When You Leave Milk Out?

If you leave your milk out of the refrigerator for less than two hours (or less than one hour on a warm day), odds are, nothing much is going to happen.

Humans can safely digest small amounts of bad bacteria without getting sick. 

However, if you leave milk out with the intention of consuming it, the odds of you getting sick are considerably higher.

The good bacteria that helps to aid digestion and build the immune system will be overcome with bad bacteria, which can cause foodborne illnesses. 

Dairy products are probably the worst food item to leave out of the refrigerator, because bad bacteria loves dairy.

Leaving milk out of the refrigerator can contaminate the milk with Salmonella, Listeria, E. coli, or Campylobacter – all of which will make humans sick. 

While some cases of food poisoning will disappear within 1–2 days, other cases can be more severe, and will sometimes lead to hospitalization. This is especially true for those with existing illnesses and a weakened immune system. 

Bad bacteria are even more likely to grow if you leave the milk out of the refrigerator when it has already been opened. The seal is there for a reason, because it stops bacteria lingering in the air from getting into the milk.

When the seal is broken, it’s easier for bad bacteria to contaminate the milk. 

How To Store Milk 

Undoubtedly the best way to store milk is in the refrigerator. Milk comes with a fairly short shelf life, but keeping it in the refrigerator will prevent any bad bacteria from forming.

It will also extend the overall shelf life and improve the flavor of the milk. 

If you have to leave your milk out of the refrigerator for some time (for example, if the refrigerator is full), there are some ways to protect it from going bad.

How Long Can Milk Sit Out? (1)

Firstly, make sure not to open the milk, as the protective seal will work as a barrier against bad bacteria. 

If possible, try to temporarily store the milk in a cool, dark place. You don’t want sun rays to hit the milk, as this will increase the temperature of the dairy and invite bad bacteria to grow.

Make sure not to keep it out of the refrigerator for longer than two hours, however. 

When you buy milk at the grocery store, always pick up the milk with the longest shelf life. These are usually located at the very back of the milk section.

The longer the shelf life, the lower the chance of food poisoning, and the longer you can use the milk without it going bad. 

Do You Need To Refrigerate Long Life Milk?

Long life milk is a type of milk that has been treated to help it last longer outside the refrigerator. This type of milk is usually stored in a dark, cool cupboard until it needs to be opened.

It is often called “UHT” milk, or “ultra heat treatment”, which refers to the treatment that extends its shelf life. 

Long life milk does not need to be refrigerated until it has been opened for use. Once the seal has broken, the long life milk needs to be treated like regular fresh milk.

It cannot stay outside the refrigerator for longer than two hours, and will need to be used until its shelf life has expired. 

Unopened long life milk can be kept outside the refrigerator for six months. 


So, there you have it! Milk cannot be left to sit out for longer than two hours. Otherwise, you run the risk of getting food poisoning. To be on the safe side, always keep your milk refrigerated. 

Mark Williams
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