Is this bottle still safe?
Four questions, one answer. The limits below come from CDC, FDA, WHO and AAP guidance, and where they differ this uses the more conservative figure.
Discard it. The limit is 2 hours.
At room temperature, reconstituted formula is an ideal growth medium: bacterial doubling time is roughly 30 to 45 minutes. Two hours is the window before counts reach clinically relevant levels.
Nothing is sent anywhere; this runs in your browser. When guidance differs between the CDC, FDA, WHO and AAP, this tool uses the more conservative figure. It never rounds towards “probably fine”.
This site provides research and comparisons, not medical advice. Consult your pediatrician before changing your baby's formula.
Every limit on one screen
The whole table, for when you would rather read it than answer questions.
| What it is | Room temperature | Refrigerated |
|---|---|---|
| Formula made from powder, not yet fed | 2 hours | 24 hours |
| Any bottle the baby has drunk from | 1 hour, then discard | Do not refrigerate it |
| Ready-to-feed, poured into a bottle | 2 hours | 24 hours |
| Ready-to-feed, opened container | Refrigerate it | 48 hours |
| Liquid concentrate, opened container | Refrigerate it | 48 hours |
| Freshly expressed breast milk | 4 hours | 4 days |
| Breast milk left after a feed | 2 hours | Keep for the next feed |
| Breast milk mixed with formula | 2 hours | 24 hours |
| Opened tin of powder | 4 weeks | Do not refrigerate powder |
The one rule people get wrong
A bottle the baby has drunk from does not go in the fridge. It is the most tempting shortcut on this page and the one with the most documented consequences. Saliva introduces bacteria; cold slows them rather than killing them, and the bottle restarts from a higher count when it rewarms for the next feed. One hour, finished or not, and then the sink.
This is also the most wasteful rule in infant feeding, which is why the practical answer is to pour smaller bottles and top up rather than making one large one and hoping.
Breast milk is not on the same clock
Worth knowing if you feed both. The AAP gives freshly expressed milk 4 hours at room temperature and 4 days refrigerated, against formula’s 2 hours and 24. Milk left after a feed is the one case where breast milk is the more permissive of the two: 2 hours, or refrigerated for the next feed, where a formula bottle would be discarded.
Mix the two in one bottle and the formula clock governs, because you cannot give the more generous limit to a liquid that now contains the stricter one. See can you mix breast milk and formula.
If it has already been fed
Most cases of a baby drinking formula past its window resolve without intervention. What to watch for, and when a call is warranted, is in what happens if my baby drinks old formula. If your baby has symptoms, contact your pediatrician rather than this page.
Related
- Storing baby formula — the reasoning behind every number above
- Preparing baby formula safely — the 70°C water rule and why it exists
- Feeding chart — how much to pour in the first place, which is how you stop wasting it
- Powder shelf life — what actually happens inside an opened tin