The thing about chemicals is.... ok, just my personal experience and 2 cents worth... The follow up to my story is this... there were a lot of positive takeaways... I have no fear of this thing called "death". A moment no more or no less. That is all. Many other positive realizations I may write about in the future.
Negative impact - When you have been to "Heaven/Nirvana etc." how do you come back to earth? I suffered deep depression. I could no longer relate to other people. Life became largely meaningless. The pursuit of wealth? Money? The "American Dream"? ... Trivial pursuits. Imagine being the only person to ever see a Sunrise? Or more accurately, the only person you personally know of that has ever seen a Sunrise? How do you describe that to other people? How can they relate to you?
So, yeah, I tried to find my way back to "the Garden" in due course and later years via experiments with drugs. There were other experiences, none recaptured the one in hospital. I tried to find my way back via other methods also... Past Life Regressions, Hypnosis, seeking out spiritual masters and Gurus. ... it goes on...
Here's the thing. I realised I was becoming a "Peak Experience Junkie". I was looking more "Hits".
But an experience is only fleeting. It's not the real deal. The carpenter said something like: Happy are those who have not seen, yet believe I go with that. I would say to others, be careful what you wish for. I hope this makes sense. Peace :)