Although there are no recorded human deaths directly attributed to LSD, we review some cases of truly reckless overdosing

‘Thus what we know for certain implies that these chemicals cannot be used without caution. But this applies equally to antibiotics, whiskey, household ammonia, the automobile, the kitchen knife, electricity, and matches.’

Alan Watts

Although it is widely acknowledged that there are no recorded human deaths directly attributed to LSD overdose, there is an apocryphal story in Peter Stafford’s brilliantly exhaustive summary of psychedelic facts and trivia, Psychedelic Encyclopedia, in which he refers to one fearless 1960s psychonaut who died after intravenously booting himself up with 320,000 micrograms – that’s over 1500 strong hits of acid, ‘mainlined’.

‘Abram Hoffer has estimated, on the basis of animal studies, that the half-lethal human dose – meaning half would die (a standard measure for drugs) – would be about 14,000 mcg. But one person who took 40mg (40,000 mcg) survived. In the only case of death reportedly caused by overdose (Journal of the Kentucky Medical Association 75:172-173), the quantity of LSD in the blood indicated that 320 mg (320,000mcg) had been injected intravenously.’

Stafford also refers to Coma, Hypertension, and Bleeding Associated with Massive LSD Overdose: A Report of Eight Cases by JC Klock, U Boerner and CE Becker in Clinical Toxicology Vol 8, No 2, 1975, in which leviathan quantities of pure LSD crystal were mistakenly snorted by eight people after a dinner party, under the assumption it was cocaine – about 40,000 mcg each, or 2,000 hits. Although they were all hospitalized and ‘required endotracheal intubation and assisted ventilation and three aspirated vomitus’, they were all ‘discharged or left the hospital within 48 hr of admission’ and ‘No residua were observed in a year of direct follow-up of five patients.’ One wonders what happened to the other three.

In his enlightening autobiographical book, LSD – My Problem Child – Reflections on Sacred Drugs, Mysticism and Science, Albert Hofmann himself presented the following conclusions about LSD, toxicity and LD50 levels:

‘The LD50 for the mouse amounts to 50-60 mg/kg IV (that is 50 to 60 thousandths of a gram of LSD per kilogram of animal weight upon injection of an LSD solution in the veins). In the rat the LD50 drops to 16.5 mg/kg, and in rabbits to 0.3 mg/kg. One elephant given 0.297 g of LSD died after a few minutes. The weight of this animal was determined to be 5,000 kg, which corresponds to a lethal dose of 0.06 mg/kg (0.06 thousandths of a gram per kilogram of bodyweight). Most animals die from a lethal dose of LSD by respiratory arrest. The minute doses that cause death in animal experiments may give the impression that LSD is a very toxic substance. However, if one compares the lethal dose in animals with the effective dose in human beings, which is 0.0003-0.001 mg/kg (0.0003 to 0.001 thousandths of a gram per kilogram of bodyweight), this shows an extraordinarily low toxicity for LSD. Only a 300- to 600-fold overdose of LSD, compared to the lethal dose in rabbits, or fully a 50,000- to 100,000-fold overdose, in comparison to the toxicity in the mouse, would have fatal results in human beings. These comparisons of relative toxicity are, to be sure, only understandable as estimates of orders of magnitude, for the determination of the therapeutic index (that is, the ratio between the effective and the lethal dose), is only meaningful within a given species. Such a procedure is not possible in this case because the lethal dose of LSD for humans is not known.’

As highlighted in following posts, such as LSD – A Curious Chemical and  Is LSD a Medicine?, there is much to suggest that not only is there no LD50 for LSD but there is little evidence for it being in any way toxic to the human body, an attribute which not only defies common sense but conventional wisdom about any synthesized, non-biological substance.

To find out more about the therapeutic properties of LSD check out the definite documentary on #PsychedelicMedicines: Neurons to Nirvana



Rory Spowers (12 Posts)

Rory Spowers is a writer, researcher, campaigner and filmmaker, based in Ibiza, Spain. His books include the critically acclaimed Rising Tides which has been compared to Rachel Carson's Silent Spring and Naomi Klein's No Logo, as a 'wake-up call to action'.