How long can a milk bottle sit out

We've all been guilty of leaving milk out of the fridge at some point in our lives. Maybe you accidentally left milk out for an afternoon after pouring a bowl of cereal, or, after grocery shopping, you ran another errand with a gallon of milk in the decidedly unrefrigerated trunk of your car. And we all know it's a bad idea to leave milk unrefrigerated for an extended period of time because it might spoil—but how long is too long? How long can milk be out of the fridge and still be safe to drink?

The answer is slightly different depending on where you live. Most of the milk consumed in France, Belgium, and Spain, for example, is UHT, or ultra-high temperature milk. This means it doesn't need to be refrigerated. But in the United States, pasteurized milk must be refrigerated, according to the US Food and Drug Administration. "By law, Grade A milk must be maintained at a temperature of 45°F or below," say food-safety specialists at Clemson University. Ideally, milk should be stored on your fridge's bottom shelf at a temperature between 38 and 40°F. That's because the bottom shelf, according to the Dairy Council of California, is the coldest part of your fridge, so it's the best spot for readily perishable items like milk.

Why do you need to be careful about the way you store milk? If milk is left out of the fridge for an extended period of time it can become a food-safety issue. Bacteria start to grow and replicate when the temperature of your milk reaches 40°F, and those bacteria are how you end up with a gallon of nasty, rotten milk or, at worst, contract an illness.

According to the US Food and Drug Administration, refrigerated foods, including milk, should never be out of the fridge at room temperature for longer than two hours. That window closes quickly if the ambient temperature rises. "If the temperature is above 90°F, food should not be left out more than 1 hour," the US Food and Drug Administration says. That's part of the reason the Dairy Council of California recommends going straight home after grocery shopping and immediately putting your milk in the fridge.

If you do accidentally leave milk out on the counter for a couple of hours, you won't necessarily get sick from drinking it—but you're not helping your chances. So refrigerate your milk as soon as you get home, and leave it in the coldest part of the fridge when you're not using it. If nothing else, you'll limit your chances of smelling rotten milk, which, in my opinion, is a win in and of itself.

By Maxine Builder and Maxine Builder

Following recommended storage and preparation techniques can maintain the safety and quality of expressed breast milk for the baby’s health.

These are general guidelines for storing human milk at different temperatures. Various factors affect how long human milk can be stored safely. Such factors include milk volume, room temperature when milk is expressed, temperature fluctuations in the refrigerator and freezer, and cleanliness of the environment.

Human Milk Storage Guidelines

Download this PDF which can be printed on magnets through a printing service.

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Safe Storage of Expressed Breast Milk

Before expressing or handling breast milk:

• Wash your hands well with soap and water. If soap and water are not available, use an alcohol-based hand sanitizer that contains at least 60% alcohol.
• Mothers can express breast milk by hand or with a manual or electric pump.
• If using a pump, inspect the pump kit and tubing to make sure it is clean. Discard and replace moldy tubing immediately.
• If using a shared pump, clean pump dials, power switch, and countertop with a disinfectant wipe.

Storing breast milk after expressing:

Do you have other questions, such as where to store breast milk at work, and what to do when the power goes out?
Visit Frequently Asked Questions.

• Use breast milk storage bags or clean, food-grade containers to store expressed breast milk. Make sure the containers are made of glass or plastic and have tight fitting lids.
  • Avoid bottles with the recycle symbol number 7, which indicates that the container may be made of a BPA-containing plastic.
• Never store breast milk in disposable bottle liners or plastic bags that are not intended for storing breast milk.
• Freshly expressed or pumped milk can be stored:
  • At room temperature (77°F or colder) for up to 4 hours.
  • In the refrigerator for up to 4 days.
  • In the freezer for about 6 months is best; up to 12 months is acceptable. Although freezing keeps food safe almost indefinitely, recommended storage times are important to follow for best quality.

Storage tips:

• 

  Clearly label the breast milk with the date it was expressed.

• Do not store breast milk in the door of the refrigerator or freezer. This will help protect the breast milk from temperature changes from the door opening and closing.
• If you don’t think you will use freshly expressed breast milk within 4 days, freeze it right away. This will help to protect the quality of the breast milk.
• When freezing breast milk:
  • Store small amounts to avoid wasting milk that might not be finished. Store in 2 to 4 ounces or the amount offered at one feeding.
  • Leave about one inch of space at the top of the container because breast milk expands as it freezes.
• If you deliver breast milk to a child care provider, clearly label the container with the child’s name. Talk to your child care provider about any other requirements for labeling and storing breast milk.
• Breast milk can be stored in an insulated cooler with frozen ice packs for up to 24 hours when you are traveling. At your destination, use the milk right away, store it in the refrigerator, or freeze it.

Safe Thawing of Breast Milk

• 

  Always thaw the oldest breast milk first. Remember first in, first out. Over time, the quality of breast milk can decrease.

• There are several ways to thaw your breast milk:
  • In the refrigerator overnight.
  • Set in a container of warm or lukewarm water.
  • Under lukewarm running water.
• Never thaw or heat breast milk in a microwave. Microwaving can destroy nutrients in breast milk and create hot spots, which can burn a baby’s mouth.
• If you thaw breast milk in the refrigerator, use it within 24 hours. Start counting the 24 hours when the breast milk is completely thawed, not from the time when you took it out of the freezer.
• Once breast milk is brought to room temperature or warmed, use it within 2 hours.
• Never refreeze breast milk after it has thawed.

Feeding Expressed Breast Milk

• Breast milk does not need to be warmed. It can be served room temperature or cold.
• If you decide to warm the breast milk, here are some tips:
  • Keep the container sealed.
  • Place the sealed container into a bowl of warm water or hold it under warm, but not hot, running water for a few minutes.
  • Test the milk’s temperature before feeding it to your baby by putting a few drops on your wrist.
  • Do not heat breast milk directly on the stove or in the microwave.
• Swirl the breast milk to mix the fat, which may have separated.

• If your baby did not finish the bottle, use the leftover milk within 2 hours after the baby is finished feeding. After 2 hours, leftover breast milk should be discarded.

Safe Cleaning of Infant Feeding Items and Pumping Equipment:

Carefully clean, sanitize, and store pump equipment, baby bottles, and other feeding items to protect your breast milk from contamination. See CDC guidance on how to safely clean and store pump equipment and infant feeding items.

• How to Clean, Sanitize, and Store Infant Feeding Items.
• How to Keep Your Breast Pump Kit Clean: The Essentials.

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Page last reviewed: January 24, 2022

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