Alicia Silverstone Fans Concerned After She Munches On Poisonous Berry

3:20 PM PT -- Alicia Silverstone confirmed she's still with us Tuesday afternoon, posting on Instagram, "Alive and well! Don’t worry… I didn’t swallow 😉😛"

Alicia Silverstone had fans freaking out over her health ... with some even asking if she was still alive ... after she munched on what they identified as a poisonous berry.

The actress was clearly, ahem, "Clueless" about her snack choice ... revealing in a TikTok clip Monday she had no idea what the orange berry was that she picked from a random bush in someone's yard during her latest UK adventure.

Alicia admitted she'd already taken a bite to figure out it wasn't a cherry tomato ... but gave it another chomp on camera, saying it kinda tasted like a pepper.

Realizing it probably should not be consumed by a human, Alicia gave fans a close-up of the berry ... which they quickly identified in her comments as a Jerusalem Cherry ... warning her it was so poisonous it could be deadly.

If you don't take their word for it, the Northern New England Poison Center says eating a Jerusalem Cherry -- AKA Solanum pseudocapsicum -- can lead to symptoms like vomiting, diarrhea, drowsiness, hallucinations and heart issues.

No official word yet on how Alicia’s doing, but she posted a few IGs after the video, so it seems she's survived. Still, a major life lesson ... don’t munch on random fruit from other people’s bushes if you can’t ID them!

We covered it all on the latest episode of "The TMZ Podcast," available on all podcast platforms.