Safely warming up baby formula and breastmilk

Follow these recommendations to ensure that a baby receives the best possible nourishment without compromising food safety.

Two baby bottles sitting on a counter.

Warming formula or breastmilk prior to feeding is not required, but may be desired. It is essential to correctly handle, store and warm the formula or breastmilk to prevent contamination and nutritional deterioration. Proper warming is also necessary to prevent burns when feeding babies. To be safe, follow these tips:


  • Warm water bath. A warm water bath is easy and convenient. Place the bottle in a bowl of warm water, or under warm running water, until milk reaches desired temperature. Take care not to leak water inside the bottle.
  • Bottle warmers. Manufacturers claim that bottle warmers heat more evenly and consistently. The disadvantage of a bottle warmer is the increased risk of overheating breastmilk and formula, which may destroy beneficial nutrients. If using a bottle warmer, use a food thermometer and test the temperature of the milk prior to serving to the baby. According to this study by Sharron Bransburg-Zabary, breastmilk should not be overheated to temperatures higher than 104 degrees Fahrenheit (40 degrees Celsius), otherwise it could compromise the nutrient quality. Always refer to the formula's manufacturer guidelines for specific warming instructions.
  • Check temperature prior to serving. No matter the method you choose for warming a bottle, before feeding, shake the bottle and test the temperature of the milk on your wrist or the back of your hand. The milk should be lukewarm, never hot, prior to serving to baby.

Additional Recommendations

  • Avoid microwaves, because they can result in uneven heating, potentially creating hot spots that might harm the baby. Furthermore, microwaving may cause nutrient loss in breastmilk.
  • Avoid reheating formula or breastmilk.
  • Use the first in, first out method for frozen breastmilk. When thawing frozen milk, do so in the refrigerator or under lukewarm, running water (ensuring the water does not leak into the container).
  • Use fresh portions only. Dispose of any remaining formula or breastmilk after feeding.
  • For freshly expressed breastmilk, you may refrigerate (40 degrees Fahrenheit or below) for up to four days and freeze (0 degrees Fahrenheit) for six months for best quality, but safe for up to 12 months. Prepared formula can be stored in the refrigerator for a maximum of 24 hours. Label the breastmilk with the date of expression before freezing.

Parents and caregivers can provide their little ones with the best possible start in life by following food safety best practices. For more information on food safety for babies, visit MSU Extension's Safe Food = Healthy Babies website for resources and articles.

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