How long can a prepared bottle be kept?

Updated 3 months ago

Why timing matters

Once formula powder is mixed with water, bacteria can begin to multiply — even if the bottle is sealed. The warmer the environment, the faster bacteria grow. Following the correct time guidelines is one of the most important safety steps in formula feeding.

At room temperature

A prepared bottle kept at room temperature should be used within 2 hours of preparation. After this point, discard any remaining formula — even if the bottle appears full or the formula looks and smells fine.

If a feed has been started but not finished, discard the remainder within 1 hour — bacteria from your baby’s mouth can transfer into the bottle and multiply quickly.

In the fridge

A prepared bottle can be stored in the fridge at below 5°C (41°F) for up to 24 hours. Place it at the back of the fridge — not in the door — where the temperature is most consistent.

To reheat refrigerated formula, place the sealed bottle in a bowl of warm water for a few minutes. Never use a microwave, as it heats unevenly and can create hot spots that may burn your baby’s mouth. Test the temperature on the inside of your wrist before feeding.

When travelling or on the go

When you are away from home, the safest option is to prepare formula fresh just before each feed using pre-measured powder and water that has been boiled and cooled. Alternatively:

• Carry pre-measured powder in a clean, dry formula dispenser and boiled water in a thermos — mix just before the feed
• Carry a prepared bottle in a cool bag with an ice pack — use within 4 hours if kept cold, or 2 hours once removed from the cold bag
• Use ready-to-feed formula for convenience when travelling — no mixing required and it can be served at room temperature

Quick reference

• Room temperature — use within 2 hours of preparation
• Started bottle — discard within 1 hour
• Fridge (below 5°C) — use within 24 hours
• Cool bag with ice pack — use within 4 hours, or 2 hours once removed
• Never freeze prepared formula
• Never reheat in a microwave
• Never save a partially used bottle for the next feed