Can You Reheat Breast Milk?

Yes, you can reheat breast milk. However, there are storage, thawing, and even reheating guidelines you have to follow. Arranging breast milk ahead of feeding time can be tricky but if you can be meticulous about it, go ahead and warm that milk!

So, it’s time to go back to work or to stop breastfeeding your little one, and you’ve turned to breast pumps. Yet, a lot of doubts hover around your mind. “Is this healthy for my baby?” “Can you reheat breast milk?” and even more.

If you’re a nursing mum, then you are at the right place. Sit tight as I proffer guidelines that will get you confidently preserving breast milk!

Can You Reheat Breast Milk?

As mentioned previously, there’s no harm in reheating breast milk for your little one.

As mothers, we all worry about the things we give to our babies. We don’t want to opt for formulas because we believe our breast milk provides the best nutrition for our babies. So, we freeze them for use at a later date.

Then, what happens when you thaw your expressed milk? Should you feed it to your baby like that? Well, you could, it’s not harmful in any way. The only thing is your baby may reject it because a lot of babies prefer their milk warm (not sure why!)

That is where reheating comes in. If carried out properly, it’s a comfortable option to feed your child.

Can You Reheat Breast Milk More Than Once?

Now you know that you can reheat breast milk. You’re tempted to reheat some a couple of times especially if your baby has milk left over from feeding time.

I just want you to know that you should not reheat expressed milk more than once! Don’t do it and for a good reason too.

  • According to the Academy of Breastfeeding Medicine, once your baby begins drinking expressed milk, saliva from their mouth will cause bacterial contamination to occur in the milk over time.
  • This bacteria can be harmful to your baby’s health, so, you should discard any leftover milk after 1 – 2 hours.(1)
  • Every time you reheat your expressed milk it may lose antibacterial qualities and valuable nutrients.

Is It Safe To Reheat Breast Milk?

If you are going to reheat your expressed milk once, it should be safe. This is so because it depends on your level of hygiene and how well you follow the guidelines on warming breast milk.

I didn’t always know these guidelines and I’m guilty of breaking them a couple of times. You, on the other hand, don’t have to do that. Just carefully follow the instructions I’ll cover later in this article.

When Is It Safe To Reheat Breast Milk?

  • The best time to heat breast milk is after it has thawed in the refrigerator.
  • Reheat expressed milk within three days after it’s kept in the fridge.
  • Warm breast milk before it hits six months in the freezer.
  • It’s sate to reheat expressed milk off the stove top most times. Breast milk does not do well in boiling water.

The above are examples of times when reheating breast milk is safe for your baby and you in extension.

When Shouldn’t I Reheat Breast Milk?

Apart from leftover bottles, there are a few other situations where it is considered unsafe to reheat breast milk; even when you’re doing it once!

Here are some of these instances where you should try to steer clear of reheating breast milk:

  • When freshly expressed milk has sat at room temperature for more than four hours.
  • Don’t reheat it if you suspect it is spoilt. Observe whether it curdles in chunks, then swirl. If it does not come together, off to the garbage can!
  • If your baby is sick or was born prematurely you shouldn’t reheat expressed milk for them. Nutrients in the milk die as it goes through the storage and heating processes. Your baby needs these nutrients! So, freshly expressed milk is the go-to option here.
  • You shouldn’t reheat previously frozen breast milk.

How To Store Breast Milk

I recently searched for YouTube videos on proper breast milk storage and I’m in awe of what I dug out.

The video will explain everything about storing breast milk to you. Still, I’m going to give you a few steps that I follow. They’re quite simple to understand:

  • Sterilize every piece of equipment you use to pump your breast milk.
  • Remember to wash your hands before you handle any breastfeeding equipment.
  • Pour the milk into glass, or plastic that is free from Bisphenol A. A simple way to determine this is to check for the number 7 on your plastic container.
  • Preferably, store them in bags made specifically for this purpose. My favorite storage bags to use are from medela.
  • Place the breast milk at the back of the freezer and not the door. Label it with the date you pumped it out. This allows you to use the older breast milk first.
  • You can add freshly expressed milk to already frozen breast milk. Only do this if the time difference between their pumping is within 24 hours.
  • Do not pour warm milk into frozen milk, it can cause the frozen milk to start thawing.
  • Freeze breast milk for up to 12 months. Though it’s best to use it before it gets to 6 months in the freezer.

How Long Can Breast Milk Stay Out?

The amount of time that breast milk can stay out of the fridge depends on its freshness.

  • Freshly expressed breast milk can stay on the counter for up to 4 hours. This range is for a room temperature of about 77°F or 25°C. If your room is a bit warmer then your breast milk will last for a shorter time.
  • Just as I earlier stated, breast milk that has been reheated will last for only 2 hours.

As soon as the time limit is passed, you should discard the breast milk. It’s not worth your baby’s health, is it?

How To Reheat Breast Milk

There are three simple methods to effectively warm breast milk. However, you have to thaw it properly.

You should not thaw breast milk at room temperature (25°C). Rather, leave it in the fridge for up to 12 hours. A good time of the day to do this will be during the night.

Thawed milk can remain in the fridge for up to 24 hours; counting from when the milk has thawed and not when you place it in the fridge.

As soon as you have done that, you have these reheating options.

  1. Reheat Breast Milk In A Bowl Of Warm Water
  • Pour warm water into a bowl and place the bottle or bag of breast milk into it. Make sure that the water is not hot and certainly not boiling.
  • As the water cools down, change it so that the bottle continues to heat up.
  • The bottle should be ready in about 5 minutes.

This is an easy process that you can carry out with the things you already have at home.

2.Reheat Breast Milk Under Running Water

Some articles I read recommended holding the bag of breast milk under running hot water and using your hands to gently break up the frozen part. I wouldn’t do this because I risk my hands getting burnt, it is hot water after all.

Instead, you should:

  • Hold the bag of expressed milk under running water. This time, start with cold. Slowly turn the heat up so that the water feels warm on your hands.
  • Gently apply pressure to the bag to speed up the thawing process.

Typically, this method takes more time than the first one. I don’t usually use this option because my little one shakes the house with her thunderous cries – okay, maybe I exaggerated a little. But it’s true, you don’t want to listen to your baby’s cries for that long, trust me.

3. Use A Bottle of Warmer

These are very effective when it comes to reheating expressed milk.

Most mothers fear that the breast milk might get overheated. This can burn your baby’s mouth. To avoid it, keep an eye on the warmer – mummy duties! – or leave it out to cool for a few minutes.

You don’t always have to go through that stress. The point of bottle warmers is to make things easier. A few high-quality bottle warmers stop raising the temperature to 98.6°F which is the average body temperature. A good example is this 5-in-1 bottle warmer from HeyValue.

Can I Use A Microwave To Reheat Breast Milk?

Don’t worry, I’ve been tempted to use microwaves so many times, you’re not alone on this one.

Microwaves are a quick way to reheat your expressed milk. But is it safe? The answer is no.

Microwaves tend to heat things unevenly. These hot spots can scald your baby. Not to mention that the bottle itself will heat up in the microwave so when your baby puts their mouth on it, they are bound to get burned.


In the end, it boils down to how well you pay attention to detail. If you’re patient enough then you can store, and safely reheat breast milk. Also, remember that these storage bags and bottle warmers are just what’s needed on your journey.

I’ll be happy to hear how your breast milk reheating quest goes. Also, let me know if you have any questions below in the comment section.


  1. Centers for Disease Control and Prevention, CDC, human milk storage guidelines; leftover from a feeding (baby did not finish the bottle).
  2. ABM Clinical Protocol #8: Human Milk Storage Information for Home Use for Full-Term Infants, Revised 2017

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