How to Warm Breast Milk the Safe Way – Tips and Techniques


Some call it “liquid gold.” Some call it “white blood.” Whatever you call it, you know just how important your breast milk is to your baby’s health. Loaded with everything your baby needs to build a healthy immune system, breast milk needs to be treated properly to ensure its nutrients are preserved.

If you’re pumping, you need to know how to store and reheat your milk safely.

Can You Reheat Breast Milk?

Reheat breast milk by warm water in the glass cup.

Yes, you can. But you need to do it properly to ensure that you don’t spoil the milk or destroy its nutrients and antibodies.

First, make sure that you store any unused milk in the refrigerator within 30 minutes after your baby is done feeding. If you let the milk sit at room temperature for too long, bacteria may start forming.

Don’t worry, you’ll know if your breast milk has gone bad. Just like with cow’s milk, breast milk will have a foul smell if it’s spoiled.

The goal is to reheat breast milk to the same temperature it is when it’s pumped directly from the breast.

While you can reheat breast milk, medical experts say it’s only safe to reheat once before tossing out the remainder. As previously mentioned, you’ll know when the milk has gone bad. It will have a strong, sour smell.

What Temperature Is Breast Milk?

When pumped, breast milk is about the same tempreature as your body temperature (around 98.6F). Your goal should be to warm the milk to this temperature or just below it. We’ll discuss appropriate temperatures and storage suggestions a little later on.

Is it Really Safe to Store Breast Milk?

Most medical professionals will tell you that you should throw out any unused breast milk, but it’s hard to throw out liquid gold isn’t it?

One study found that there is no significant difference between unused and partially consumed milk. The milk was stored at between 39.2F and 42.8F for 12-36 hours, reheated to 98.6F, fed partially to the baby and then stored again in the refrigerator for another 48 hours. Clean – not sterile – techniques were followed in the initial storing and feeding.

What’s the Best Way to Warm Breast Milk?

A prohibition for a bottle of breastmilk in the microwave.

There’s a right way and a wrong way to reheat breast milk. And if you don’t do things the right way, your baby may not get the nutrients she needs to build a healthy immune system.

Let’s talk about the things you shouldn’t do before we talk about the things you should do.

What Not to Do When Heating Breast Milk

Breast milk, just like cow’s or goat’s milk, is sensitive to heat, but human breast milk is a little more sensitive than normal.

When reheating your breast milk, please do not do the following:

  • Boil: Boiling breast milk can cause it to spoil and will destroy all of its nutrients.
  • Microwave: Microwaving breast milk is also a big “no no,” as it will only destroy all of the beneficial properties of the milk. Microwaving can also cause hot spots, which can be dangerous for your baby.

How to Heat Breast Milk Properly

There are a few ways to safely heat breast milk, depending on how the milk was stored.

Warming Breast Milk From the Fridge

Bottles of breast milk in fridge.

Breast milk should be stored in the refrigerator at below 39 degrees and for a maximum of 8 days (72 hours is ideal). Keep the milk in the back of the refrigerator for best results.

To reheat, warm the refrigerated milk under warm running water for several minutes, or until the milk reaches body temperature.

You also have the option of gently warming by immersing the milk in a pan of heated water. Make sure the water isn’t boiling. The water should be warm – not hot.

You may also heat expressed milk in the same way.

Never heat milk directly on the stove.

Some babies are also okay with drinking the milk right out of the refrigerator, which makes things a little easier for mom.

When milk is stored in the fridge, the fat usually separates from the liquid. Don’t worry, this is completely normal and the milk is still safe to drink (provided you haven’t exceeded the recommended storage time). Shaking the breast milk will incorporate the fat, so make sure you do this  before you reheat and feed.

Warming Frozen Milk

Several bags of frozen breast milk on white table.

Breast milk can also be stored in the freezer and will stay fresh for longer. When stored at 0F, the milk will stay fresh for three to six months. And if you store it in a deep freezer, it will stay good for six to twelve months at –4F.

Frozen milk should be thawed in the refrigerator overnight. If you don’t have time for a good thawing, you may run cool or lukewarm water over the milk to thaw it out a little quicker.

Increase the temperature of the water gradually to bring the thawed milk to the appropriate feeding temperature.

Again, do not use the microwave to reheat the milk – not even the defrost setting. Your breast milk needs to be reheated gently even if it’s frozen.

Thawed milk can be stored in the fridge for up to 24 hours if it was defrosted in the refrigerator. If you defrost at room temperature, it should only be stored for four hours in the fridge.

Thawed milk sometimes has a rancid or sour smell, that’s due to the high lipase activity that occurs when the milk is frozen or chilled.

If your baby has a hard time drinking the milk because of the smell, you can try scalding (not boiling) the expressed milk and then quickly cooling it before freezing it. This technique, which is considered completely safe, will deactivate the lipase enzyme and prevent the smell.

Can You Refreeze Breast Milk?

There is limited evidence that breast milk can be refrozen. Even if you put it back in the freezer within just a few hours, you’re further degrading the nutrients and the antimicrobial properties of the milk.

What About Warming Breast Milk on the Go?

Travel bottle warmer equipment on white background.

You’re a busy mom. Unfortunately, you can’t spend every waking hour at home, and why would you want to? You have errands to run and other things to do.

How can you reheat breast milk while you’re out and about? Use a bottle warmer for breast milk.

There are travel bottle warmers that will intelligently reheat your milk to just the right temperature, so you can safely feed your baby. There are also home versions of these warmers, so you don’t have to worry about whether the water in your pot or from the tap is too hot. The warmer will heat the milk to just the right temperature every time.

While you can reheat milk on the go, it’s still important to use common sense. Keep the milk cool when traveling to prevent bacteria, and make sure that you heat to just the right temperature. If the milk smells bad, it probably is bad and it’s best not to risk your baby’s health – just toss it.

Many moms swear by travel bottle warmers, and it gives them the freedom to go about their daily activities without having to worry about how they’ll feed their baby.


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