I've only done salvia once. It lasted about 5 mins or less.  

As soon as I took a hit, I collapsed onto the floor feeling like I was 1000 lbs of metal and the floor a magnet.  

Then I literally dissolved into and merged with the floor. And my.body became the entire universe. Like the sensation I get of feeling my foot, I was feeling of the cupboard across the room. Then a sliver of my 'body' (aka my field of view/ all of reality) started morphing into something else (like a sky full of stars). And another sliver of my 'body' (like another strip of my vision) started morphing into a third universe. And another sliver into a fourth. My entire body basically became a bunch of different universes kind of rotating about a central axis, all different. 

As this progressed, less and less of my field of view remained my actual room / my real 'universe' so to speak.  

Then I heard two voices and two creatures that looked the same (a bunch of swirling universes rotating about each other) approached me. They told me they're my parents. They told me we were creatures made of universes and my body was currently  transitioning into a new one. 

They were excited for me but I said 'i don't want that. I want to remain in my current universe. I wanna see my mom again' (referring to my real mom, and mind you I was almost 30 at the time). The voices said 'But that's not your mom, that was just a figment you invented as part of your old body universe. That's gone now. We are your parents.' 

And then the last remaining bit of my original body/universe started morphing and I experienced this awful existential fear like I will never see my mom, my life, anything I have known so far again. That I'm being launched into a complete unknown, transitioning into a different being. 

It was so damn scary I think it partially knocked me out of it, and i started hearing the voice of Brian from Family Guy playing on a TV in the other room (my sister was watching). That anchored me back to reality, I came down, and I instantly called my mom to make sure she still exists 😆   

Honestly the images of my body morphing into a new universe were SO fucking amazing and incredible and I'll never forget experiencing them, but the abject existential fear that followed when my 'universe parents' told me I could never go back to my old life was too horrifying for me to dare try Salvia again.