Storing Breast Milk

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Collecting breast milk is a way of giving your baby breast milk in a bottle. If you collect milk, you can store it so you don't have to use it right away.

Why store breast milk?

Storing breast milk lets you feed your baby later or allows someone else to do it. This is useful if you're going back to work or will be gone at feeding time. It's also a way to give your baby breast milk if he or she can't breastfeed.

How long can you store breast milk?

Breast milk can be stored in the following ways:

  • Kept at room temperature [60 °F (16 °C) to 85 °F (29 °C)] for 3 to 4 hours. If the milk was collected under clean conditions, such as by using properly washed hands and properly cleaned pump parts and containers, milk may be kept at room temperature for 6 to 8 hours.
  • Kept fresh in a cooler with an ice pack [59 °F (15 °C)] for 24 hours.
  • Stored fresh in the refrigerator [39 °F (4 °C)] for up to 4 days. If the milk was collected under clean conditions, it may be stored for 5 to 8 days.
  • Kept in a freezer [0 °F (-18 °C)] for up to 6 months.

How can you store breast milk safely?

Here are tips for storing breast milk safely.

  • Wash your hands before pumping or handling milk that will be stored.
  • Use plastic bottle liners, small freezer bags, or glass bottles for storage.
  • Wash storage containers in hot, soapy water or in the dishwasher.
  • Write the date that the milk was pumped on the outside of the bag or bottle.
  • Thaw frozen breast milk carefully.
    • Run warm water over the storage container until the milk becomes slushy.
    • You can also thaw breast milk overnight in the refrigerator. Then warm the breast milk by setting it in lukewarm water for 20 minutes.
  • Don't refreeze thawed milk.
  • Don't use thawed (and then refrigerated) breast milk after 24 hours.
  • Don't use a microwave for warming milk. Microwaves create hot spots in the milk that can burn your baby's mouth and throat.
  • Experts say it's best to throw away any breast milk left in the bottle after a feeding.


Current as of: November 9, 2022

Author: Healthwise Staff
Medical Review:
Sarah Marshall MD - Family Medicine
Kathleen Romito MD - Family Medicine
Adam Husney MD - Family Medicine
Kirtly Jones MD - Obstetrics and Gynecology

The Health Encyclopedia contains general health information. Not all treatments or services described are covered benefits for Kaiser Permanente members or offered as services by Kaiser Permanente. For a list of covered benefits, please refer to your Evidence of Coverage or Summary Plan Description. For recommended treatments, please consult with your health care provider.