If you are wondering whether you can reheat prepared formula, you are not alone. This is one of the most common bottle-feeding questions parents ask, especially when trying to avoid waste and make feeding routines easier. The short answer is that untouched prepared formula can be stored safely and warmed later, but a bottle your baby has already started drinking from should not be saved for another feeding.
Below is a simple guide to when reheating formula is okay, when it is not, and how to warm refrigerated formula more safely.
Can You Reheat Prepared Formula?
Yes, but only in certain situations. If you prepared a bottle and your baby has not started drinking from it, that bottle can be refrigerated and used later within the recommended safe storage window. If your baby has already fed from the bottle, the leftover formula should be thrown away rather than saved for another feeding.
That is because saliva mixed into the bottle can increase bacterial growth once the feeding has started.
How Long Can Prepared Formula Sit Out?
If prepared formula is left at room temperature, it should be used within 2 hours of preparation. Once your baby starts feeding, the bottle should be used within 1 hour. After that, any leftover formula should be discarded.
If you do not plan to use the prepared bottle soon, refrigerate it promptly and use it within 24 hours.
How to Reheat Refrigerated Formula
If a prepared bottle has been refrigerated and has not been used yet, you can warm it before feeding if you want to. A bottle warmer is one option, but warming is not strictly necessary. Many babies will take formula at room temperature or cool from the refrigerator.
If you prefer to warm it, place the bottle in warm water for a few minutes and then test a few drops on the inside of your wrist. It should feel lukewarm, not hot.
What You Should Not Do
- Do not save formula from a bottle your baby already drank from.
- Do not leave prepared formula sitting out too long.
- Do not microwave formula, because it can heat unevenly and create hot spots.
- Do not reheat the same bottle over and over again.
Helpful Formula Storage and Prep Resources
- Can You Refrigerate or Freeze Formula?
- How to Measure Baby Formula Without a Scoop
- Baby Formula Preparation Guides
- Holle Formula Preparation Guide
- HiPP Formula Preparation Guide
Frequently Asked Questions
Can you reheat baby formula?
You can warm refrigerated formula once before feeding, but formula does not need to be warmed. If your baby has already started drinking from the bottle, discard leftovers within 1 hour.
Can you reheat formula twice?
No. Reheating formula more than once is not recommended. Warm only what you plan to use and discard leftovers after feeding begins.
Can you microwave baby formula?
No. Do not microwave baby formula because it can create hot spots that may burn your baby's mouth.
How do you warm formula from the fridge?
Place the bottle in a container of warm water, then test a few drops on your wrist. The formula should feel warm, not hot.
How long can warmed formula sit out?
After warming refrigerated formula, feed it right away. Once feeding begins, use or discard the bottle within 1 hour. Do not save warmed leftovers for later.
For the safest results, always follow the preparation and storage instructions on your formula label. If your baby was premature, has a weakened immune system, or has special feeding needs, ask your pediatrician for personalized guidance.
Related Formula Collections
If you are comparing formula options, you can browse our European Organic Baby Formula collection and our Stage 1 Formula collection.