How To Tell If Breast Milk Is Bad? Don’t Throw It Out Just Yet!

Regardless of the method you choose to feed your baby, each comes with its own challenges and concerns. If you’re nursing, the last thing you want is your pumped milk to go to waste.

Most moms agree: there’s nothing worse than throwing away that precious liquid gold.

After hours of relentless pumping and feeding, each drop of mom’s milk becomes an extension of yourself. A stash of great milk is also most convenient for a solo run to the store without a feeding timer ticking away.

In this article we’ll go over the method for storing your milk to ensure utmost longevity, hygiene, and safety, the tell-tale signs that a bottle of breast milk has gone bad, as well as what happens when a baby consumes bad breast milk.

Is My Pumped Breast Milk Still Good?

The appearance, taste, and smell of breast milk are not the same as normal dairy milk.

Because of this, determining whether your pumped milk is still good by “inspecting” the same way you would do with normal dairy milk will not give you an accurate answer.

Following safety guidelines with regards to pumping and storage is imperative in ensuring your breast milk is still at its nutritional and safety peak when fed to your baby.

How To Store And Prepare Breast Milk

The Centers for Disease Control and Prevention provide guidelines for the storage of breast milk.

However, factors such as milk volume, the temperature when milk is expressed, changes in refrigerator and freezer temperature, as well as the cleanliness of the environment affect the milk’s quality when stored.

How To Safely Pump Breast Milk For Storage And Consumption

Before expressing or handling already expressed breast milk, wash your hands thoroughly with soap and water, or an alcohol-based sanitizer if the former are unavailable.

Before starting, inspect the pump to ensure cleanliness. If the tubing looks moldy, replace it immediately.

As the CDC emphasizes, clean pumping equipment, bottles, and other feeding items help protect breast milk from contamination.

How To Store Breast Milk Once Expressed

Invest in breast milk collection bags, clean glass or plastic food-grade containers with tight-fitting lids.

As the CDC warns, bottles marked with recycle symbol number 7 should be avoided as this can mean that the plastic may contain BPA.

Disposable bottle liners or plastic bags should not be used for storing breast milk.

How Long Can I Store Breast Milk For Before It Goes Bad?

At room temperature (77°F or colder) Up to 4 hours
In the refrigerator Up to 4 days
In the freezer 6 months is best, up to 12 months is acceptable

Adapted from CDC Guidelines

The MayoClinic reminds parents and carers that breast milk starts to lose Vitamin C the longer it’s stored.

In addition, milk expressed when the baby is still a newborn might not sufficiently meet her needs once she’s a few months older.

Tips For Storing Breast Milk To Ensure It Doesn’t Go Bad

As MayoClinic recommends, use waterproof labels and ink to clearly label each container with the date the breast milk was expressed. This way you’ll know if the milk has been stored for far too long. Add baby’s name if milk will be used at childcare.

Breast milk should be placed at the back of the refrigerator or freezer where the temperature is coolest. Avoid the door of the refrigerator or freezer as there will be too many temperature fluctuations every time the appliance is opened.

Each container should hold enough for one feeding. Store some portions with only 1 or 2 ounces for instances where smaller amounts are needed.

Once frozen, breast milk expands, so don’t overfill containers! Leave an empty inch to allow for expansion.

Freeze milk right after expressing if you don’t think you’ll be using it in the coming 4 days.

Think you might be having a trip coming soon? As the CDC notes, breast milk can be stored in an insulated cooler bag with frozen ice packs for up to 24 hours. But, once you’re at your destination, use the milk immediately or store in the refrigerator or freezer if still frozen.

Experts suggest that you only store breast milk for two weeks if your freezer is a compartment within your refrigerator.

Using Frozen Breast Milk

When it comes to making use of your milk stash, always thaw the oldest first as the longer the milk’s stored, the lower the quality is. The CDC offers these options for thawing breast milk:

  • Overnight, in the refrigerator
  • In a container of warm or lukewarm water
  • Under lukewarm running water

And here’s what you should NOT do when thawing breast milk:

  • Never use the microwave to thaw or heat breast milk. Breast milk nutrients and microwaving aren’t the best of friends; plus, the microwave can create hot spots in the milk which can scald the baby.
  • Never refreeze breast milk once thawed.

Breast milk has to be used within 24 hours of it being thawed in the fridge. Once you warm it up for use, it should be consumed within 2 hours.

What Does Good Breast Milk Look Like?

The answer to this question is not so straightforward – as the smell, taste, and appearance of breast milk changes from woman to woman as well as from time to time for the same mom.

As the MayoClinic notes, there are differences in the odor and consistency of fresh breast milk and thawed milk. This does not mean that the thawed breast milk has necessarily gone bad, though.

Nonetheless, if your baby refuses to drink the thawed milk, shorten its storage time.

The smell of breast milk is easily affected by the food you’re consuming, any medication you might have been taking when the milk was expressed, the freezing process, as well as the storage method used.

The color of good breast milk can range from yellow to off-white, to blue-tinged and slightly orange. The color can also change within the same pumping session due to the increase in fat content the longer the pumping session.

At times, breast milk can also taste or smell soapy. The fat in the milk can break down during storage, causing this smell. Nonetheless, the milk is still safe.

There is no one norm when it comes to breast milk: a difference in color, taste, or smell does not necessarily mean that it has gone bad.

So how can we know when breast milk does indeed turn bad and is no longer safe for baby to consume? Here are some signs to look out for:

Signs That Stored Breast Milk Has Gone Bad

Stored Too Long

If the breast milk has been stored for longer than the guidelines recommend (see above), then it should be thrown out.

Inappropriate Storage

Really, we could easily cry at the thought of improperly stored liquid gold. There’s nothing worse than taking out a bag of breast milk and realizing it wasn’t sealed properly.

Sorry, but inappropriately stored milk has to be binned – it must be done despite the heartache.

Temperature Fluctuations

Earlier on, we wrote about the importance of storing breast milk in a place in the refrigerator or freezer which does not experience too many temperature fluctuations.

If your breast milk has been stored on freezer door shelving, then its lifespan is much shorter.

A dedicated milk bin might come in handy – that way you’re not frantically looking for space to store your newest stash with the fridge or freezer wide open.

Unclean Pumping Gear

Bacteria can live in your pump’s tubing and parts. When this ends up in the milk, it can lead to nasty side effects on your little one.

Throw away milk expressed via a dirty pump.

Note from Michelle Roth, BA, LCCE, IBCLC: “Check your pump parts often and get rid of any that show signs of not coming fully clean after washing.

Follow your pump manufacturers cleaning instructions closely to keep your individual pump from contamination.”


Spoiled milk smells sour and should not be consumed.

Diverse Consistencies

When swirled, thawed milk should go back to one homogeneous consistency. If the milk remains separated, with fat solids floating on top, it should be discarded.


Breast milk color varies but there are some red flags with some hues – it’s straight to the bin if there’s black or dark green mold.

A rosy tinge may mean blood in the breast milk. Read more about blood in breast milk below. This milk is still safe for your baby to consume.

Curdled Milk

Whilst the thickness of breast milk can change when expressed, chunks in the milk are a bad sign.

Milk curdles when the pH levels drop. This allows fat proteins to attach to each other, as happens when the milk is heated.

If the milk’s looking chunky, it’s time to throw it away.

Off Taste

You might not be too fond of tasting your own milk, but doing so is best when you’re not sure about its scent.

Breastmilk typically tastes rather sweet. If the milk tastes sour, it’s best not to give it to your little one. If it’s not good enough for you, then it surely is not good for the baby.


If your baby is refusing the milk or spitting it out, it’s probably turned bad. Try it out yourself before chucking it out if your baby is simply hesitating.

Milk can change its taste when stored and still be good. If the baby is all out refusing the milk, it’s best to throw away.

Drink – Pause – Drink

If your baby is playing up with her bottle, and you’re tempted to heat and re-heat, think twice.

Breast milk should only be warmed up once. Heating milk after it’s been cooled provides the perfect environment for bacterial growth.

Oops! Forgot The Milk

Life with a baby is hectic so you’re 100% forgiven for forgetting that bottle of milk on the kitchen counter.

Unfortunately, though, milk left out for more than 6 hours should be ditched (3 hours on hot days!).

This is the same for milk left in the refrigerator for too long. CDC guidelines indicate that refrigerated breast milk should be consumed within 4 days.

Medicine And Alcohol

Some medication is not safe for breastfeeding mothers, as it could affect the baby through breastmilk. If you could not do without, it’s best that milk expressed when on medication is thrown away.

Note from Michelle Roth, BA, LCCE, IBCLC: “While a single drink should not cause any interruption in breastfeeding, this may not necessarily be true with pumped milk.

According to the CDC, pumping milk within two hours of drinking may mean that the milk should be discarded.”

Sorry, the fun ends with the realization that the milk has to be thrown away!

Blood In Breast Milk

There can be a number of reasons why your expressed breast milk is tinged with blood.

Breastfeeding Support outlines the following factors: rusty pipe syndrome, damaged or cracked nipple, damaged breast capillaries, intraductal papilloma, and fibrocystic changes.

According to the La Leche League, breast milk tinged with blood is usually still safe for baby. Nonetheless, if it has a significant amount of blood, the baby might reject the milk as it may have a metallic taste due to the excess iron.

This taste will get stronger if the milk is refrigerated or stored. As noted by Livestrong, it might be best to offer it to your little one immediately as it is expressed to avoid throwing the milk out.

Why You Should Never Give Spoiled Breast Milk To Your Baby

In her input for Romper, Lactation Consultant Danielle Spradlin states that babies will very likely throw up spoiled breast milk.

Generally, babies who get sick from pumped breast milk do so because of cross-contamination. This emphasizes the importance of proper expressing and storage hygiene practices.

Cross-contamination occurs when foods with a contaminant like salmonella or E. coli are handled at the same time as breast milk.

Some signs that the milk you’re feeding your baby is spoiled will come from the baby herself. If she’s squirming or rejecting the milk, it’s best to stop trying to give it to her.

It should not be overly worrisome if your baby vomits after consuming spoiled milk, but if the vomiting continues, call your pediatrician.

The National Institutes of Health lists the following symptoms to look out for if baby had spoiled milk:

  • High fever
  • Blood in stools
  • Diarrhea
  • Prolonged vomiting
  • Dehydration
  • Signs of shock such as a weak or rapid pulse or shallow breathing

Seek immediate help if your little one is showing any of these symptoms.

Wrapping It Up

Nothing comes quite close to the pride of seeing a whole freezer stashed with liquid gold.

Expressing is hard work, and for many, considerably time-consuming.

With the pumping and storing tips above, you can ensure that your treasure trove remains safe for consumption.

Nonetheless, some things are out of our control, and with parenthood does come a good dose of baby brain with a great dose of busyness. There are instances where you will end up questioning, ‘Is this milk still good?’

As we have seen, identifying breast milk that has gone bad is not always so straightforward. The bottom line is, trust your gut instinct, and do not be overly hesitant about throwing away bottles you’re unsure about.

With feeding, baby’s safety always comes first!

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Medically Reviewed By: Michelle Roth, BA, LCCE, IBCLC

Medically Reviewed By: Michelle Roth, BA, LCCE, IBCLC

Michelle Roth, BA, LCCE, IBCLC is a board-certified lactation consultant for two busy pediatric practices. She is a former La Leche League Leader, Lamaze Certified Childbirth Educator, and Certified Infant Massage Instructor. She has taught classes ranging from healthy pregnancy, to childbirth preparation, to parenting, and more.

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