How to Know If Frozen Breast Milk Has Gone Bad

Freezing breast milk is necessary for some mothers, and others do it by choice to have a built-up supply of milk for their babies. It’s important to freeze expressed breast milk properly – using a storage bag or container, placing it in the back of the freezer and labeling the containers with the date – but even diligent mothers may question whether their frozen breast milk has gone bad. Some easy solutions to help you determine whether the frozen breast milk is still good, but if you’re ever in doubt, throw it out rather than taking the chance of feeding your baby spoiled breast milk.

Check the date on the container. Breast milk will stay fresh in a deep freezer for up to six months, a regular freezer for three to four months and a freezer compartment inside the refrigerator for up to two weeks. If the frozen breast milk is outside of these ranges, it may be spoiled.

Thaw the breast milk completely. Place frozen breast milk in the freezer overnight to thaw or hold the container or bag under warm running water to thaw the milk. Don’t place frozen breast milk in the microwave or in boiling water to thaw.

Swirl around the bag or container gently to mix up the breast milk. This will blend the liquid and separated fat in the milk and will give you an accurate smell and taste.

Smell the breast milk. Spoiled breast milk will have a rancid, sour smell 1.

Taste the breast milk if you’re still unsure whether or not it’s spoiled. Fresh breast milk will have a sweet taste. Spoiled breast milk will taste sour and you will be able to tell that it’s bad.


Always use the oldest breast milk in the freezer first. Label containers or storage bags with the date the milk was placed in the freezer to help you determine the freshness of the milk.

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