How long does kefir last in the fridge?
Quick answer
- In the fridge
- Unopened: about 1 week · Opened: 1–2 days
- In the freezer
- Not recommended
Sources: USDA FoodKeeper · Last reviewed October 1, 2026
Kefir keeps about 1 week in the fridge below 4°C, and USDA's FoodKeeper advises finishing an opened bottle within 1–2 days. Its live cultures keep making it tarter and fizzier the longer it sits. Mild fizziness and tartness are normal (it's a fermented product); a harsh sour-rotten smell or fuzzy mold are not. Shake before pouring; natural separation is normal.
How to store kefir
Keep kefir on a middle or back shelf, never the door. Tightly sealed in the original container. Live cultures are sensitive to temperature swings. Shake or stir gently before each use to redistribute solids that settle to the bottom. Freezing kills most cultures and changes the texture; use frozen kefir only for smoothies. Open kefir for use, then return immediately — leaving it on the counter accelerates fermentation.
- Middle or back shelf, sealed
- Shake before pouring
- Return to fridge promptly after pouring
- Don't store in door — temperature swings
- Freeze only for smoothies
Signs it has gone bad
- Sharp rotten or putrid smell
- Fuzzy mold on surface
- Bitter or chemical taste
- Slimy or stringy texture
Frequently asked questions
How long does kefir last after opening?
USDA's FoodKeeper advises finishing opened kefir within 1–2 days; unopened, it keeps about a week in the fridge.
Is fizzy kefir bad?
Mild fizz is normal — kefir is fermented. Strong fizziness, harsh smell, or bitter taste mean it's past its prime.
Can you freeze kefir?
It isn't recommended — freezing kills most of the live cultures and changes the texture. Use frozen kefir only in smoothies.