Will milk go bad if left out overnight?

In this article, we will answer the question “Will milk go bad if left out overnight?”, what happens if you drank milk that was left out overnight, how to store milk to prevent spoilage, how long does the milk last, and how to tell if the milk has gone bad.

Will milk go bad if left out overnight?

It depends on the room temperature. Discard the milk if it has been sitting out at 90F for more than an hour. If the temperature is lower than 90F, the milk may last 2 hours or just a bit longer. This only applies to opened and pasteurized milk.

If we are talking about unopened UHT milk that is left out overnight at room temperature, it won’t go bad. But it is better to err on the side of caution and inspect the milk for spoilage before using it.

What happens if you drank milk that was left out overnight? 

Pasteurized milk is not invincible. It goes bad when let out overnight. Drinking spoiled milk has the same repercussions as eating any spoiled food. That is, you will get food poisoning. 

Common symptoms include nausea, diarrhea, vomiting, and stomach pain. Symptoms should not persist for more than 3 days. If they do, seek medical help. 

How to store milk to prevent spoilage?

Make sure the milk stays at refrigeration temperature or lower at all times. Tick off the milk at the end of your grocery shopping. So that you can minimize the time that milk spends outside of refrigeration. Put it back in the fridge as soon as you get home.

However tempting it may be to put your milk cartons or bottles in the fridge door, do not do it, not unless you want to reduce the shelf-life of the milk by half. 

The fridge door is where most of the temperature fluctuations happen. Frequent exposure to temperature fluctuations expedites the spoilage of milk.

Ideally, you should keep your milk container in the coldest spot inside the fridge which lies where the ice tray is located, usually at the bottom or at the back of the fridge.

It is important that the milk container, original or not, has a sound seal. A tight seal keeps the air, bacteria, unwanted odors, and other contaminants at bay. If the seal of the original milk container is broken, transfer the milk to an air-tight container.

UHT and canned milk can sit out as long as they are opened. Even then you should make sure that the outside temperature does not go abnormally high. Once opened, they belong in the fridge.

If you are a parent and want to pack milk in lunch for your kid. Do it by sandwiching the milk bottle in ice packs. Better yet, pack them a shelf-safe or UHT milk bottle. Instruct them to finish the bottle after opening it. Once the UHT milk is opened, it is treated like any other type of milk.

What is the shelf-life of milk?

If the package is solid and the seal is intact, you can expect your milk to last 7 days past the printed date. Once opened, no type of milk should be kept for more than a week. Opened milk is best consumed within 5 days.

If you want your milk to last longer, say for up to 4 weeks, reposition it from the fridge to the freezer. This does not mean you will wait till the last supposed day of the shelf-life of refrigerated milk and suddenly decides to freeze it to ‘save it’.

There is no saving the milk that has reached the limit of its shelf-life under refrigeration. So, you should plan ahead of time. If you do not intend to use the milk within the next 5 days, or at least not use all of it, freeze it.

How to tell if the milk has gone bad?

Smell: Spoiled milk smells sour due to the lactic acid produced by the spoilage bacteria.

Appearance: If you suspect the milk is spoiled, you are looking for a ropy or lumpy texture and a yellow color. 

Mold: Mold grows on milk in the form of white or green patches or spots. Get rid of moldy milk if you spot it.


In this article, we answered the question “Will milk go bad if left out overnight?”, what happens if you drank milk that was left out overnight, how to store milk to prevent spoilage, how long does the milk last, and how to tell if the milk has gone bad.




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