A molecule born from ergot
In popular discourse, LSD is often wrapped in its countercultural aura: the Summer of Love, psychedelic posters, and police raids. It is worth remembering that, before all of that, it was a laboratory compound coldly cataloged, and its own inventor described it in the dry language of pharmacology. That perspective—Hofmann the chemist rather than the prophet—is what we recover here from his technical papers, where he left details that his autobiography, LSD: My Problem Child, barely touches upon.
The origin lies in ergot, the fungus Claviceps purpurea that infects rye and darkens its grains. This parasite—feared for centuries due to the mass poisonings it caused—also contains alkaloids of enormous therapeutic value. At the Sandoz laboratories in Basel, Hofmann succeeded in synthesizing one of them, ergometrine, the oxytocic principle of ergot. All these alkaloids share the same skeleton: lysergic acid. Numerous derivatives were prepared from it, among them diethylamide, dubbed LSD-25, initially conceived as a possible respiratory stimulant (analeptic) due to its structural similarity to nikethamide.
The accident that revealed its potency
The compound had gone almost unnoticed until, while handling it again years later, Hofmann felt a strange, though not entirely unpleasant, state of intoxication. Suspecting the molecule, he decided to test it deliberately. The amount he chose as a trial dose—which he judged to be prudently small—turned out to be five to ten times higher than what would later be recognized as an active dose. The result was an experience so intense that his own account already described the fundamental effects of the substance. Shortly thereafter, psychiatrist W. A. Stoll, at the University Psychiatric Clinic in Zurich, conducted the first systematic study of its effects on healthy volunteers and patients.
Potency is the most striking data point. LSD is, by far, the most active classic psychedelic known: on the order of two hundred times more so than cocaine or amphetamine, and about ten thousand times more than mescaline. For Hofmann, this was not an anecdotal curiosity but a first-rate pharmacological clue: the fact that a handful of micrograms is enough to transform consciousness suggests that the molecule does not act diffusely, but rather on very deep and central structures of the nervous system, at some regulatory point that we still do not fully understand today.
Potency is not the same as danger… or safety
A nuance is necessary here that Hofmann’s own era could not formulate with the caution we demand today. The fact that a substance has low acute toxicity does not make it harmless. In animal experiments, the median lethal dose (the LD50, the dose that kills half the animals in a group) varied enormously by species: on the order of tens of milligrams per kilogram in mice and rats, but a much smaller fraction in rabbits, where death occurred via respiratory paralysis. Compared to the human active dose—in the range of micrograms per kilogram—these figures suggest a seemingly wide margin.
However, that margin describes only acute physiological toxicity in laboratory animals. It says nothing about the real risks of human consumption: acute psychological crises, the reactivation of latent psychiatric conditions, accidents resulting from altered perception, interactions with other substances, or the fact—not minor in the current market—that what is sold as LSD may not be LSD at all. Reading “low toxicity” as “safe” is precisely the kind of leap that a critical reading must avoid.
Distribution that defies intuition
If a molecule transforms the mind, one would expect to find it concentrated in the brain. Studies with radioactively labeled LSD in mice showed just the opposite. After administration, the compound disappears quickly from the blood and is distributed throughout various organs, reaching its peak at ten to fifteen minutes before falling rapidly. Paradoxically, the lowest concentration of all was found in the brain. The small intestine was the exception, with levels that continued to rise for a couple of hours; elimination occurred primarily through the liver, bile, and intestinal tract.
Even more striking: two hours later, barely a tiny fraction of the compound remained as intact LSD; the rest were already water-soluble metabolites. Since the psychic effect reaches its peak when most of the substance has already left the tissues, Hofmann deduced something that remains dizzying: infinitesimal doses are enough to trigger a cascade of reactions whose effects persist long after the physical presence of the molecule. LSD seems less like a substance that acts by its mass and more like a trigger that sets a process in motion.
Three planes of pharmacological action
Under the direction of Professor Rothlin and, subsequently, Dr. Cerletti, the Sandoz laboratories described the effects of LSD on three planes. In the peripheral plane, its action on smooth muscle stands out, particularly the oxytocic effect so characteristic of ergot alkaloids. In the neurohumoral plane, its ability to antagonize serotonin (5-hydroxytryptamine) is notable: at very low concentrations, it blocks the peripheral effects of this neurotransmitter, an observation that would eventually open an entire line of research into the role of serotonin in the mind.
On the central plane, LSD configures what Hofmann summarized as an ergotropic stimulation syndrome: visible activation on the electroencephalogram, increased sensitivity to sensory stimuli, signs of sympathetic activation (dilated pupils, increased temperature, piloerection), and heightened reflexes. Not everything, however, is stimulation: in certain tests, the substance showed depressant effects, for example, potentiating barbiturate anesthesia in rodents. In general, the doses required for these effects in animals far exceeded those that alter the human mind.
And that is, at heart, Hofmann’s most honest recognition: what is truly specific about LSD are not those measurable physiological effects, which are secondary in humans, but its extraordinary psychic effects. Such a molecule, he said, offered an unprecedented tool for experimentally studying the relationship between body and psyche: modifying the chemical structure, comparing the effects, and reading into those correlations something about the old enigma of how the material translates into experience.
Critical reading
Hofmann’s text is a document of its time, and it should be read as such. Terms like “psychotomimetic” or “hallucinogen,” which he uses naturally, reflect the psychiatric framework of the 1950s—the idea that these substances mimicked psychosis—which is widely debated today. The figures for potency, toxicity, and distribution he cites come from Sandoz research and must be understood in their experimental context, not as a guide for use.
None of the above is an invitation to consume or a practical guide. Legitimate fascination with the history of psychedelic chemistry coexists with a simple fact: the current market is opaque, the composition of what circulates rarely matches its label, and psychological risks are not reflected in any LD50. The best harm reduction remains honest information and skepticism toward readings that confuse potency with danger, or the absence of acute toxicity with safety. The original references Hofmann cited (the works of Stoll, Rothlin, Cerletti, and collaborators published in journals such as Experientia or Helvetica Chimica Acta between 1943 and 1956) are mentioned for their historical value, without links, for those who wish to track them down in specialized sources.
