Can You Rewarm Breast Milk? Is That Safe?

How Many Times can you rewarm breast milk

Key Points

  • This article answer your question – how many times can you rewarm breast milk and also discusses the guidelines for rewarming breast milk, emphasizing safety precautions and best practices.
  • It covers topics such as proper storage, rewarming methods, temperature checking, and discarding leftover milk to maintain freshness and prevent bacterial growth.
  • Refrigeration of rewarmed milk is not recommended, as its quality may be compromised and the risk of bacterial growth increased.
  • Frozen milk should be thawed in the fridge or under cold water, with its temperature checked before feeding.
  • Rewarmed milk should be used within 1 hour and any leftovers discarded thereafter.

Every mom who breastfeeds wants to make sure her baby gets the best milk. Breast milk is like magic for newborns because it’s full of stuff they need to grow strong and healthy. But sometimes, you end up with extra milk or your baby doesn’t finish what’s in the bottle. So what happens when you have leftover expressed milk, or your baby doesn’t finish their bottle? Can you rewarm breast milk to avoid waste, and if so, how many times is it safe? This guide will tell you everything you need to know so you can take care of your baby the best way possible.

How Many Times Can You Rewarm Breast Milk?

When it comes to warming up breast milk, it’s usually a good idea to only do it once. You see, every time you heat it up, some of the good stuff in the milk, like the important nutrients and antibodies, can start to break down. Plus, when you warm it up again, it can make it easier for bacteria to grow, which could make your little one sick.

But sometimes, you might need to heat it up twice. If that happens, try to use the milk within an hour after rewarming it again. That way, you can lower the chances of anything bad happening.

How Many Times Can You Rewarm Unused Breast Milk?

Like I just mentioned in the previous section, when you warm up breast milk for your baby, it’s best to do it just one time. And if your little one doesn’t finish the bottle, it’s important to throw away any milk that’s left after two hours. This helps make sure that the milk doesn’t get any germs from your baby’s mouth, which could make them sick. So, warm it up only once, and if there’s any left after two hours, it’s time to toss it out!

Type of Breast MilkCharacteristicsRecommendation
Unused Breast Milk (freshly expressed or thawed)Not exposed to baby’s salivaCan be rewarmed twice if stored correctly (refrigerated or frozen). Priority should be given to freshly warmed milk for optimal benefits.
Leftover Breast Milk (partially consumed)Exposed to baby’s saliva during feedingRewarming multiple times significantly increases risk of bacterial growth. Discard any leftover breast milk after one feeding to avoid potential illness in your baby.

Can You Rewarm Breast Milk in the Microwave?

No way! Using the microwave to warm up breast milk isn’t a good idea. Microwaves don’t heat things evenly, so some parts might get too hot and ruin the important stuff in the milk. Plus, they can mess up the good things like antibodies and enzymes that help keep babies healthy.

For more detail, please read: Why Can’t You Microwave Breast Milk? – Why It’s NOT Safe

If you need to warm up breast milk fast, stick to safer ways like putting the bottle in warm water or using a special bottle warmer made for this job. It’s better to be safe than sorry when it comes to feeding our little ones!

Can you rewarm breast milk in the Microwave

Can You Rewarm Breast Milk Twice?

When you’re thinking about rewarming breast milk again and again to save it or to avoid waste, it might seem to be tempting. But it’s actually not a good practice at all. Every time you warm it up, there’s a chance that bacteria could grow in it, and it might lose some of its nutrients. It’s better to think ahead and only thaw or warm up as much milk as your baby will need for one meal. That way, you can avoid any problems and make sure your baby gets the best milk possible.

Can You Rewarm Breast Milk Multiple Times?

I have already talked about this before. Well here is again, no problem. When you warm up breast milk over and over again, it can make it easier for bacteria to grow in it and for the good stuff in the milk to break down. Every time you warm it up, it gets to a temperature that helps bacteria grow. So, if your baby drinks milk that’s been rewarmed a bunch of times, they might get sick from the bacteria. It’s better to just warm up what your baby needs for each feeding instead of rewarming the same milk multiple times.

Why Can’t You Rewarm Breast Milk Multiple Times?

The rewarming the breast milk for multiple times is not a good idea for two big reasons.

First off, each time you rewarm it, some of the good stuff in the milk—like important vitamins, minerals, antibodies, and enzymes—can start to disappear. These things are super important for helping your baby’s immune system grow strong and keeping them healthy.

Secondly, breast milk can naturally have some good bacteria in it, which is great for your baby. But if it’s not handled carefully, bad bacteria can also get in there. Rewarming the milk creates a warm environment that bad bacteria really like, and they can grow fast, which might make your baby sick.

Can You Rewarm Refrigerated Breast Milk?

Absolutely, you can warm up breast milk that’s been chilling in the fridge. You know, the milk you’ve just pumped can hang out in the fridge for about 4 days. When it’s time to warm it up, just remember to be as careful as you would be with frozen milk. I am going to explain those below.

Best Ways to Rewarm Breast Milk

To warm up breast milk safely, you can try two methods:

The first one is a warm water bath. You just need to put the breast milk container in a bowl of warm water. Make sure the water isn’t too hot. Every now and then, swirl the container in the water to heat it evenly. Before feeding, test the temperature on your wrist to make sure it’s not too hot.

Another option is to use a bottle warmer. These are made specifically for warming up bottles easily. Just follow the instructions that come with the warmer to make sure you’re doing it right and not overheating the milk.

Remember, never heat breast milk directly on the stove or in boiling water. It can make some parts of the milk too hot and ruin it.

Health and Safety Considerations

Precautions When Rewarming Breast Milk

First things first, if you’ve got frozen breast milk, make sure to thaw it out before using it. You can do this by popping it in the fridge overnight or running it under cold water. Don’t try to thaw it out at room temperature or in hot water, okay?

Now, when you warm up the milk, be careful not to make it too hot. You want it to be just right, like your own body temperature. A good way to check is by putting a drop on your wrist before giving it to baby.

Once you’ve warmed up the milk, try to use it within 1 hour. And if there’s any left after that, it’s best to toss it out. Better safe than sorry!

How Long Can You Keep Rewarmed Breast Milk?

Rewarm any leftover breast milk and use it within an hour. If there’s any milk left after you’ve rewarmed it, make sure to throw it away within 1-2 hours after it’s gotten back to room temperature. This way, we can be sure it hasn’t stayed in the danger zone (between 40°F and 140°F) for too long, which helps stop bacteria from growing too much. Remember, if there’s any milk left after an hour, it’s best to get rid of it.

How Many Times can you rewarm breast milk

Can You Refrigerate Rewarmed Breast Milk?

Nope, you shouldn’t put back rewarmed breast milk in the fridge because it messes with its quality and can make bacteria grow faster. Stick to the “one-hour rule” instead. Here’s why:

  1. When you heat up milk and then cool it again, it goes through a bunch of temperature changes. That’s not good for it because it’s best to keep breast milk at a steady temperature.
  2. Plus, each time the temperature changes, it gives bacteria a chance to grow, especially if the milk didn’t cool down fast enough before you put it in the fridge.
  3. Also, all these temperature changes can make some of the good things in breast milk start to disappear, and that’s not what you want.

When Shouldn’t I Rewarm Breast Milk?

There are a few situations where it’s best to avoid rewarming breast milk:

  • Milk Has Been at Room Temperature for More Than 4 Hours: Freshly expressed breast milk can be stored at room temperature for up to 4 hours. If the milk has been at room temperature for longer, discard it and offer fresh or refrigerated milk.
  • If the milk has been thawed and not used within 24 hours: Thawed breast milk can be stored in the refrigerator for up to 24 hours. However, if it hasn’t been used within that timeframe, it’s best to discard it and offer fresh or frozen milk.
  • If the storage container shows signs of leakage or damage: Leaky containers can allow bacteria to contaminate the milk. Discard any milk stored in a compromised container.
  • If you’re unsure about the storage time: When in doubt, throw it out! It’s always better to err on the side of caution and provide your baby with fresh or safely stored milk.
  • Previously Frozen and Thawed Twice: Breast milk can be thawed in the refrigerator or under cold running water. However, refreezing thawed milk is not recommended due to potential nutrient loss and bacterial growth. If milk has been thawed twice, it’s best to discard it.
  • Signs of Spoilage: Spoiled breast milk may have a sour smell or appear curdled. Discard any milk that shows signs of spoilage.

Also, if your baby doesn’t finish the breast milk within one to two hours after feeding, it’s best to throw away the leftovers to stop bacteria from growing and making it unsafe.

Expert Advice on Breast Milk Rewarming

The American Academy of Pediatrics (AAP) says it’s best to only heat up breast milk once and use it within 2 hours. They also suggest not using microwaves to warm it up.

American Academy of Pediatrics (AAP)

On the other hand, La Leche League International (LLLI) highlights how important it is to store and handle breast milk properly so you don’t have to rewarm it as much. They suggest using a cool-mist humidifier near your baby if they don’t like room temperature milk.

La Leche League International (LLLI)

Final Words

Breast milk is super important for your baby’s health. When you need to warm it up, it’s usually safe to do so. But, it’s really important to store and handle it right to keep all the good stuff in there. You should know how often to rewarm it and follow the best ways to do it. That way, every time your baby eats, they get all the good nutrients. Just trust your gut as a mom, and don’t hesitate to ask for help from pros along the way with breastfeeding.


Can you reuse breast milk if baby doesn’t finish bottle?

If your baby doesn’t finish the bottle, you can still use the leftover breast milk within 2 hours after feeding. After 2 hours, you should throw away any remaining milk. To avoid wasting milk, try storing, thawing, and warming it in smaller amounts.

Can I put breast milk back in the fridge after warming it up?

Healthcare professionals, like lactation consultants and pediatricians, usually advise not to put warmed breast milk back in the fridge. Once breast milk is warmed to feeding temperature, bacteria can start growing faster.

How long can breast milk sit out after rewarmed?

Once you’ve warmed breast milk, you should use it within two hours. It’s important to find a good storage bottle that’s free of plastic. This keeps your breast milk safe. To thaw frozen breast milk, you can put it in the fridge, hold it under running water, or place it in warm or hot water.

Can you store bottles with nipples attached?

When putting away baby bottles, make sure to take off the nipples first. Keeping the nipples on the bottles when you store them is not a good idea. It can cause germs to build up, which is not safe for your baby.

Can you shake breast milk?

Before you check the temperature of the breast milk, gently swirl the bottle. This helps to mix the milk evenly and distribute the heat throughout. Be careful not to shake the bottle hard. Shaking too much can harm some of the important nutrients and live cells in the milk. These nutrients and cells are very good for your baby, so it’s best to treat the milk gently.

Can I pump into the same bottle all day?

Experts say it’s usually safe to mix breast milk from different pumping sessions. Just make sure the milk is pumped on the same day and kept at the same temperature. You can then store it all together in one container.


  1. Thawed breast milk: Do not reheat again and again –
  2. Heating Human Milk in the Microwave:
  3. Nutrient composition of Human milk (per 100g):
  4. Is It Safe to Reuse Breast Milk? –
  5. Can Warmed Breast Milk be Refrigerated Again? –
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