Interestingly there was posted an article (
https://www.wired.com/2017/01/ever-really-long-acid-trip-now-science-knows/ ) about it taking a longer time for LSD to leave the claustrum (a particular part of the brain), but that certainly doesn't mean it stays in your body forever - the half life is still like that ^ otherwise LSD would not be found excreted in the body and the half life would be insanely long or infinite. So still very much a myth.
It's also interesting you recommend that we check the research on it, although to be fair myths like that are copied all across the internet by people alarmed rather than diligent, no offense tho.
@marko: The data for deaths etc seems really limited though, articles linked to earlier for example take just one recorded casualty for mushrooms to make calculations which hardly qualifies as calculations. That it's so difficult to find reliable fatality cases, especially ones without extenuating circumstances, and enough of them to clearly link involvement of mushrooms and LSD attests to their relative safety and focusing on the people that have indeed died seems like a witch hunt and missing the overall point.
On-topic though: I thought LSD was thought to be a little less safe for things like mental instability or HPPD compared to mushrooms, which would not be consistent with your theory. Unfortunately I do not know if those are only inferences based on LSD 'not being natural like mushrooms' even though it is only semi-synthetic so nearly natural, or just having a longer duration. Also @ mental instability, a big study found links between psychedelics and mental illness to be very poor which brings into question the validity of comparing safety and mental instability to begin with.
As for HPPD, that one might be true as things like efficacy / affinity / potency which are often linked seem to make a difference for HPPD. NBOMe's are also considered relative HPPD hazards for example.
Instant trips may refer to flashbacks or psychosis which are also long stories that are not quite so simple. Flashbacks can be positive or neutral for example (the only one I ever had was not bad at all), just associated with ultra intense and emotionally imprinted memories. Also if you learn more about PTSD which flashbacks may be associated with (the nasty kinds though), again that is about the extreme and traumatizing nature of an experience and there is no drug necessarily required for that, war is another typical cause. So it's not that LSD does this, just that it can produce trips intense and fucked enough to be traumatizing. Nobody ever said LSD is not powerful.
