Short answer: keep raw kombucha in the fridge. Unopened, it’s at its best until the date on the bottle – for one US maker, 6 months for cans and 8 months for glass bottles (brand claim). Once opened, recap bottles tightly and put them straight back in the fridge; it’s best finished within about a week, while it’s still fizzy. Homemade kombucha keeps for weeks in the fridge but slowly turns more sour and vinegary. Throw it out if you see fuzzy mold or it smells rotten rather than tart.
Kombucha Shelf Life at a Glance
| Kombucha | Guidance |
|---|---|
| Store-bought, unopened, refrigerated | Best until the printed date. Brew Dr. dates cans 6 months and glass bottles 8 months (Brew Dr.). |
| Store-bought, opened | Recap and refrigerate; finish cans once opened. Best within about a week, while still fizzy. |
| Homemade, bottled | Refrigerate as soon as it’s as fizzy and sour as you like; it keeps getting more sour. |
| At room temperature | Keeps fermenting: more sour, more pressure, more alcohol. Refrigerate raw kombucha. |
The date on the bottle is a quality date for the unopened product: the maker guarantees flavor, fizz and cultures until then, but can’t once it’s opened (Brew Dr.).
Why Kombucha Must Stay Cold
Raw kombucha is still alive: yeasts keep turning sugar into alcohol and carbon dioxide, and bacteria keep turning some of that into acids. Cold slows this almost to a stop. Warmth restarts it, which means:
- More sour and vinegary flavor.
- More pressure in a sealed bottle – it may gush when opened.
- More alcohol. US rules treat kombucha as an alcoholic beverage if it reaches 0.5% alcohol at any point, including after bottling through continued fermentation (TTB). When New Zealand researchers tested nine commercial kombuchas, two (22%) exceeded that country’s 1.15% limit (Nordstrom et al., 2026).
Kombucha left in a hot car also suffers: heat damages the live cultures and the flavor (Brew Dr.).
Homemade Kombucha
- Bottled kombucha: refrigerate as soon as it’s as fizzy and sour as you like. It’s best within a few weeks, after which it gets flatter and more vinegary.
- Second-fermentation bottles left warm can build dangerous pressure. Chill them before opening, point them away from people and open slowly over the sink – see our second fermentation guide.
- Too sour to drink? Over-fermented kombucha is essentially kombucha vinegar: use it in dressings, or as starter for your next batch – see our kombucha brewing guide.
Signs Kombucha Has Gone Bad
- Mold: dry, fuzzy spots (blue, green, black or raised white) on the surface or on a baby SCOBY in the bottle. Discard.
- A rotten, putrid or cheesy smell, rather than tart and vinegary.
- A store-bought bottle that has been left warm for a long time and is bulging or gushing – it has kept fermenting.
Normal, not spoiled: a jelly-like blob or thin film floating in the bottle (a new SCOBY forming), brown stringy yeast strands, sediment at the bottom, and a more sour taste over time. Strain them out if you prefer.
Unopened Kombucha Left Out
Most raw kombucha is labeled “keep refrigerated”. A bottle that has been out for a short time isn’t necessarily spoiled, but it will have kept fermenting – more sour, more fizzy and possibly more alcoholic. Chill it well and open it carefully. If it has been warm for days, or it smells or looks wrong, throw it away.
More: fermented drinks like kombucha and how to store fermented foods.
