First, we should be clear that overripe doesn't always equate to rotten, even in the case of the fickle pineapple. That said, pineapple food poisoning is certainly possible, though rare. ... So no, rotten pineapple is not technically "poisonous," though it can certainly make you sick due to a number of factors.

Will fermented pineapple juice make you sick?

No, fermented juice is NOT safe to drink.

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.

Can you get sick from eating fermented fruit?

While most fermented foods are safe, it's still possible for them to get contaminated with bacteria that can cause illness.