Feeding

How long does made-up formula last, and can I reheat it?

Q: How long does made-up formula last, and can I reheat it?

Made-up formula is safest used straight away. If you need to store it, the NHS advises using within 2 hours if left at room temperature, or up to 24 hours if refrigerated immediately after making (and not previously warmed). Once your baby has started drinking from a bottle, use it within 1 hour or discard — bacteria from their mouth multiplies fast. Never reheat formula in a microwave; it heats unevenly and can scald.

The NHS storage rules, in full

Room temperature: use within 2 hours of making up, or discard.
Fridge (0–4°C), made fresh: can be stored up to 24 hours if refrigerated immediately after cooling — but freshly made for each feed is the recommended approach, and pre-made batches are really a backup for genuinely difficult moments (like overnight feeds), not the routine.
Once baby has fed from it: use within 1 hour, then discard the rest. Saliva introduces bacteria that multiply quickly at milk temperature.
Never refreeze or reuse formula that's been warmed once.

Why microwaves are a hard no

Microwaves heat unevenly, creating "hot spots" that can scald your baby's mouth even when the bottle feels fine to the touch when shaken. Warm bottles by standing them in a jug of warm water or using a bottle warmer instead, and always test a few drops on your wrist before feeding.

The travel-friendly approach

Many parents use pre-measured formula dispensers with cooled boiled water carried separately, making up a fresh bottle only when needed — this sidesteps the storage-time question entirely for feeds away from home.

Health answers describe NHS guidance and are not medical advice — for anything urgent, call 111 (or 999 in an emergency). Spotted something out of date? Email editors@clevermum.co.uk.