How long does breastmilk last at room temperature

How long does breastmilk last at room temperature

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As a lactation consultant working with women at the very early stages of breastfeeding, I always mentioned that the baby doesn’t always need to get the milk direct from the breast every time. Expressing milk into bottles for later can ease the reliance on the mother to feed but ensure they are still getting the best nutrition – breast milk.

What I do mention, however, is how milk needs the direct interaction from time to time to change with the baby. What this means is that baby literally tells the mum what milk they need at that moment in time – it may not be to the minute but some examples are – day and night milk, milk for when their poorly, milk for when they’re hungry and milk for when they are in a growth spurt.

I’ve started with this introduction to ensure readers that expressing full time will keep the milk exactly the same. Babies need different milk as they grow older and your body will work with them to do that.

Anyway, now that’s out the way – how long can you keep your milk fresh if it’s out in the open and not in the fridge or freezer.

Expressing breastmilk and storing it is one of the best ways to continue breastfeeding on the go. It’s ideal for mums who want to get back to work but don’t want to stop feeding their child, for example. Or, if they decided they want to feed them but don’t want to have as much of the physical side of it. Alternatively, expressing also means a partner can help with the feeds.

However, just like cow’s milk; breastmilk can go off once it’s left the breast as it can be invaded by bacteria which can make your baby sick.

How long it takes to spoil isn’t an exact science but the CDC have guidelines here and there is a general rule of thumb and plenty of ways to help you store the milk to extend its life.

For that it’s worth, I don’t generally recommend leaving milk out at room temperature at any time – it is so easy to put it in the fridge or the freezer that the risks far outweigh the benefits.

What is room temperature?


Room temperature is what feels comfortable to the person. However, IUPAC says it’s 25 degrees, US EPA is 20-25 degrees whereas normal people like you and I would say it’s 20-22 degrees.

Room temperature is basically what your house is most of the time. Check your thermostat whenever you think “this feels right” and that will be that.

How long can I keep expressed breastmilk at room temperature?

Generally, breastmilk will last 4 hours at room temperature before it spoils and shouldn’t be fed to children, confirms Lucy Upton (the children’s dietician). But, this really does depend on how the expressed milk has been stored and where it has been stored and whether or not it is freshly expressed breast milk or milk was has been thawed.

This means, however, that the best type of expressed milk to take on a trip out locally is freshly expressed as it gives you a 4-hour window.

Below, we will break down some different scenarios

How long can refrigerated breast milk be left out at room temperature?

Milk which has been taken out of the fridge should be consumed within 2 hours. This sounds counterproductive considering fresh breast milk can last 4 hours at room temperature. Putting breast milk in the fridge can keep it going for up to 5 days but it reduces its viability once out of the fridge and at room temperature.

If you plan on going out of the house for longer than 4 hours then it’s best to take freshly expressed milk with you rather than milk which has been stored and taken out of the fridge.

Do not put room temperature milk back in the fridge, if your baby doesn’t want it – keep it at room temperature for a little longer or dispose of it.

How long can frozen breast milk be left out at room temperature?

Frozen milk should never be left to thaw at room temperature or it will be spoil quickly. Instead, thaw the frozen expressed milk in a fridge and then it can be left at room temperature for no more than 2 hours, same as above. Freezing is a fantastic way to express and keep milk over a long period of time (as long as a year!) but care needs to be taken once it’s about to be used.

How long can half drank expressed milk be left out at room temperature?

Once the expressed milk has been opened and drank a little, finish off the rest or throw away within 2 hours regardless if it is freshly expressed and not refrigerated or frozen. This is because the milk now has some saliva and bacteria from the baby’s mouth and will spoil quickly.

Should I leave expressed breast milk at room temperature?

There is absolutely nothing wrong with leaving expressed milk at room temperature as long as it’s consumed relatively quickly and stored properly (more on that soon). However, one of the problems with leaving expressed milk out is that many may not remember how long it’s been there or whether it’s been drunk out of already and not all ‘room temperatures’ are the same.

But the question of should you leave breast milk out at room temperature is down to you. If you follow the above guidelines and store properly (more in a little) then you will have no issues with this, in fact safely leaving at room temperature can be very convenient at times.

What happens to breast milk if left out too long?

When breastmilk leaves the nipple the special ingredients can quickly breakdown and become less nutritious, when milk is refrigerated or frozen it will start to lose vitamin C. Your milk is also tailored to your baby so key antibodies can begin to degrade. Lastly, as with any foodstuff, bacteria can get inside the milk and grow which can in extreme cases make your baby sick.

How do I know if my milk has been left at room temperature for too long?

Some people cringe at the thought of tasting their own breastmilk or for someone to taste someone else’s breastmilk but we think it’s important that parents know what their milk is like when it’s fresh so they can taste or smell the difference if it isn’t. When milk has been left at room temperature for too long it gets a distinct sour smell and taste which is caused by the bacteria.

How to properly store breast milk at room temperature

To maximise the duration stored breast milk can last before spoiling really does depend on safe storage and a good location. Here are some quick-fire room temperature milk storage guidelines to help you out

Store in a sealed container

simple air tight container

If milk can be stored in a sealed airtight container it will limit the number of bacteria which can get to it. There are many you can get on the market with removable lids so when it’s ready to be consumed you can swap one lid for a lid with a teat or a sippy cup. Ensure that the container, whatever it is, is cleaned and sterilised before putting your expressed milk inside!

Be clean

Before expressing and then putting in a bottle, ensure you’ve washed your hands and that you’re using clean containers made of glass or BPA free plastic. Ensure anyone else who will be using the containers or the milk was their hands also.

Keep away from heat

Room temperature is a commonly used phrase for ‘feels fine’ but in reality, different parts of the room can be hotter and cooler. Keep your breast milk away from radiators, direct sunlight, kettles and ovens as this could be warmer than you think and it’s the warmth which can make the bacteria grow in the milk.

Maximise using the fridge and the freezer

Storing as much as you can in the freezer and fridge will mean there is an abundance available so you won’t feel the need to keep it out at room temperature so much. Invest in milk storage bags for the freezer, empty bottles for the fridge and so on.

Invest in a thermos for days out

Thermos Stainless King Food Flask

Storing expressed breast milk in a bottle and then putting it in a bag or pram to take out counts as ‘room temperature’. To combat this, consider investing in a baby thermos which keeps the milk warm or cold depending on the temperature it’s at when it goes in. This can prolong its viability once you’re out of the house when you don’t want to breastfeed and can’t express.

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