A common question I get is whether or not a ferment is safe to consume. I’ve received this question so many times that I feel it’s time to make a post about it. One of the most commonly asked questions is if fermented juice is safe to drink. Here are my thoughts.

No, fermented juice is NOT safe to drink.
My response assumes you are asking because your juice spontaneously fermented. As in, you did not set out to make a fermented drink.
Instead, you bought some grape juice or pineapple juice, and it stayed in the fridge too long and now it’s bubbly and fizzy. Or maybe it’s the orange juice you’ve been drinking for the past week. You forgot to put it back in the fridge for several hours, and suddenly it’s got some bubbles and a tang.
You know that people purposefully ferment drinks to make natural, probiotic sodas, so you’re wondering if this is the same general idea.
The answer is no, it couldn’t be farther from the same thing. Your spontaneously fermented apple juice is not the same as cider, and is not safe to drink.
What happens when juice ferments spontaneously?
When juice ferments spontaneously, often it is due to contamination with bad bacteria. This is particularly the case if it is a pasteurized beverage, because all the good bacteria has already been killed.
But even a raw juice that spontaneously ferments isn’t necessarily safe to drink. It could be tainted with harmful bacteria such as E. coli or salmonella and make you very sick.
Bacteria and yeasts gobble up the sugars in the drink and release gases and ethanol. It results in a drink that is bubbly with a low alcohol content. This drink should be regarded as spoiled.
I’d avoid whether the juice was pasteurized or raw.
And when anyone asks me if “randomly” fermented drinks are safe, I will always say NO. Of course some will choose to drink them and things may turn out OK. But I would never advise it.
Drinking spontaneously fermented beverages can make you sick.
What’s the difference between a spontaneously fermented drink and a lacto-fermented drink?
Spontaneously fermented drinks are not created under any kind of controls. It is generally due to products being kept at too warm of a temperature, or not being used within the designated period of time. Generally juices recommend keeping them under refrigeration, and discarding within 7-10 days of opening.
Intentional fermentation is the complete opposite. When you intend to ferment, you put the juice in the right environment to ensure a safe end product.
Lacto-fermented drinks almost always contain a starter. If they do not, such as beet kvass, they are still fermented under controlled environments, generally with salt added to help stunt growth among harmful bacteria and allow lactic acid bacteria to flourish.
I personally also ferment beet kvass and similar ferments under anaerobic conditions, which also greatly decreases the odds of promoting the growth of bad bacteria and yeasts.
When fermenting fruit juices, I generally use a starter such as ginger bug or water kefir. These starters quickly drop the pH of the juice and crowd out any bad bacteria that may be in it. The starters help good bacteria flourish in the fermented juice, and have a preserving effect.
Even when home brewers are fermenting wine/alcohol, they will generally add something to kill the natural cultures before adding their own yeast.
What shoud you do if you accidentally drank fermented juice?
If you accidentally drank some juice that was sitting too long, then you need to somewhat play it by ear.
Rest assured that you don’t need to jump to the conclusion that you’re going to die.
Chances are that the worst that will happen is you’ll have some digestive distress, like a stomachache or diarrhea. Here are some tips for dealing with belly pain.
In some cases, you may have more serious digestive issues such as vomiting. If you have a little nausea or vomit once or twice and then feel better, then it’s safe to assume that your body did a good job of clearing the irritant.
However, if you have persistent diarrhea or vomiting and don’t seem to be getting better, you may want to consult your doctor.
Aly
Tuesday 12th of August 2025
Hi!! I can upon this because I was noticing - I would make my midday smoothie (I double it up in the same jar for a 12pm and 3pm meal) and by the time I’d get to my 3pm - I was a bit more sour and definitely would fizz on opening!
I thought th is was so bizarre! Everything was fresh when I made it!
Turns out my carrot juice - thought still good in its separate container was fermenting - so over those 3 hours of sitting in my jar and a bit of heat .. it would ferment!
I drank it the few times it’s been happening haha but probably won’t anymore as I noticed today when I opened my carrot juice it fizzed a bit!
Confederate patriot
Thursday 31st of July 2025
I create fermented juice and wine all the time the old fashioned way. Just get it warm and then open the bottle and leave it outside for a few hours or I just take the top off after I am outside for a bit and take a few drinks over a little while. Your lips will pick up yeast outside and start the ferment. Or I use some bread or wine yeast to start the ferment.
After any of these I also let them go all the way to wine sometimes and then sometimes all the way to vinegar.
I just always make sure to leave the cap just resting on top to CO2 can get out and air(o2) can get in so that I don't risk dying of botulism. So always make sure that you do NOT seal the container. Just use a rubber band w a paper towel.
Why Is My Orange Juice Fizzy? Safety & Causes Explained
Saturday 10th of May 2025
[…] to food safety experts, even small amounts of contaminated juice can cause digestive distress. The risks outweigh any […]
Wiratech
Friday 2nd of May 2025
Your post is worthy of everyone's attention. I'm excited to learn more and more. Thanks for sharing! Mesin Es Batu
Ron T
Wednesday 16th of April 2025
I can confirm that drinking spontaneously fermented cherry juice can make you sick. I’m sitting on the toilet right now, having diarrhea because I drank cherry juice that was fermented. I usually mix my cherry juice with water so I didn’t notice that it was bubbly. I decided to have some without water and I noticed it was bubbly and an hour later I’m sitting here on the toilet.