LSD's effects were discovered by accident on April 16, 1943

Swiss chemist Albert Hofmann discovered the mind-altering effects of LSD by accident on April 16, 1943, when a trace of the compound he was working with at Sandoz Laboratories in Basel got into his system, probably after he touched his face. He had first made lysergic acid diethylamide in 1938 while screening derivatives of ergot, a fungus that grows on rye, and Sandoz had shelved it as a possible stimulant for breathing and circulation.

That afternoon he felt strange, went home, and with his eyes closed saw what he later described as “an uninterrupted stream of fantastic images”.

Was Bicycle Day the day LSD was discovered?

No. The famous date, April 19, marks a different event: Hofmann’s deliberate self-experiment three days later. He carefully measured out 0.25 milligrams (250 micrograms) and recorded the results in his journal, where the last words he managed were “desire to laugh”. The ride home, during which he could not tell he was moving, gave the day its name.

His measured dose was anything but cautious. A 2021 placebo-controlled study by researchers in Basel found LSD produces noticeable effects from just 25 micrograms, with positive effects levelling off at about 100 micrograms; above that, ego dissolution and anxiety climb. Hofmann swallowed ten times the smallest dose that produced clear effects in that study, and two and a half times the point where the good effects plateau. He later remembered the experience as terrifying.

Is LSD used in medicine?

It was tried, banned, and is being tried again. Hofmann believed LSD could serve psychiatry and neurology, and from the late 1950s researchers tested it against alcoholism and some mental disorders until it was made almost universally illegal in the mid-1960s. Hofmann, who titled his memoir LSD, My Problem Child, was dismayed by its recreational use. Today scientists are again testing it as a therapy.