Safe Storage Times For Breast And Formula Milk

Understanding the rules around breast and formula milk storage and shelf life can be confusing. In this post we simplify it and provide a clear guide. Whether you are making up formula or expressing breast milk, general hygiene practices are important to ensure safe storage.

• Always wash your hands before expressing milk or making up formula.
• Ensure the tools and storage equipment have been cleaned and sterilised.
• Have labels to hand or create a system to note the date and time so that storage times can be calculated.
• Make sure containers used for storage are well sealed.

Safe storage times for breast and formula milk

Breast Milk
Can be safely kept at room temperature for 4–6 hours. If in doubt or for babies in NICU or experiencing ill health, stick to 4 hours.

Can be safely kept refrigerated (at 4°C or less) for 5–7 days. If unsure of your fridge temperature, store for 3 days max. Always store in the coolest part of the fridge (close to the back), avoiding the door.

Can be safely frozen for up to 6 months.

When thawing frozen breast milk, you can thaw under warm water or slowly in the fridge. Once thawed, use within 2 hours if kept at room temperature or within 24 hours in the fridge. Don’t refreeze thawed breast milk.

Formula Milk
The safest way to prepare formula feeds is to make them up fresh when needed. Follow the instructions on the formula pack, using the appropriate amount of boiling water and allowing for cooling time.

Although not recommended, formula milk can be kept at room temperature for a maximum of 1–2 hours.

If needed, prepared formula bottles can be stored in the fridge (at 4°C or less) for up to 24 hours.

It is not recommended to freeze formula feeds.

Once baby has consumed some of a bottle (either breast or formula), it is safe at room temperature for 1 hour. After this, discard any remaining milk.

Is it safe to combine breast and formula milk in one bottle?

Yes, if done safely.

If you want to top up a bottle of expressed breast milk, you can add pre-made formula or make up a smaller amount of formula as normal and add it to the breast milk. Try to ensure both are a similar temperature — bring formula to room temperature before mixing with freshly expressed milk to protect the live components. If refrigerating before feeding, do not add warm milk to cold milk, as this raises the temperature and affects safe storage times.

When making powdered formula to mix with breast milk, always follow the pack instructions and use the appropriate amount of water. Breast milk cannot replace water in formula preparation.

Combined bottles can be stored at room temperature for 1–2 hours (1 hour if baby has already drunk from the bottle) and in the fridge for up to 24 hours.