I don't know about n,n-DMT (which is a potent hallucinogen and for what simply DMT is a conventional shorthand for) but for 5-MeO-DMT (which is a distinct subst

I don't know about n,n-DMT (which is a potent hallucinogen and for what simply DMT is a conventional shorthand for) but for 5-MeO-DMT (which is a distinct substance, very weak hallucinogen yet tremendously strong psychedelic) - it's not unlikely to die if you overdose. Doses above 25mg are dangerous, 100mg is probably an almost guaranteed physical death. You just experience being so free from the concepts of material (and mental) reality, one with G-d, Universe and everything, that you can (and will, if the dose is enough) forget about your physical body and it stops breathing. Curiously enough this substance seems being safe and even very beneficial as long as the doses are reasonable and this attracts scientific attention. I.e. I've read the following paper recently: A single inhalation of vapor from dried toad secretion containing 5-methoxy-N,N-dimethyltryptamine (5-MeO-DMT) in a naturalistic setting is related to sustained enhancement of satisfaction with life, mindfulness-related capacities, and a decrement of psychopathological symptoms (DOI: 10.1007/s00213-019-05236-w).