Today in History—April 19: The Very First Acid Trip in History

On this day in 1943, Swiss research chemist Albert Hofmann conducted an outlandish experiment—on himself. He dosed himself with 0.25 milligrams of lysergic acid diethylamide, and then he…went for a bike ride.

Hofmann’s work focused on isolating pharmacological compounds from medicinal plants. In 1938, while searching for circulatory and respiratory stimulants in ergot—the rye fungus later (and often poorly) linked to theories about the mass hysteria behind the Salem witch trials—he synthesized a new compound: lysergic acid diethylamide.

He named it LSD-25, because it was the 25th variation he’d tested. It did not seem especially promising at the time.

Discover the fascinating events that shaped the world, straight from our editors.

SIGN UP

By clicking “Sign Up”, you consent to the Britannica Privacy Policy and Terms of Use.

But it nagged at him, so, more than five years later, he returned to the compound and resynthesized it. During the process he touched his face and accidentally absorbed a small amount of the chemical through his skin. Soon after he reported feeling strange and restless and then seeing a “kaleidoscope” of colors. The sensations lasted about two hours.

We know that compound today as LSD.

Three days later, on April 19, Hofmann did what any good scientist would do: He set out to recreate the experiment with controlled variables. He ingested 0.25 milligrams of lysergic acid diluted in water, at 4:20 pm.

By 5 pm the effects had begun. His notes from that afternoon provide the first documented acid trip in history: He vacillated between feeling like he was floating and feeling deeply anxious and fearful.

He ended the experiment abruptly, with the following note: “Home by bicycle.” (He was smart enough to conduct this experiment with his assistant, so he had an escort—but it still must have been one wild ride.)

And now April 19 is observed as Bicycle Day—mostly by LSD enthusiasts, not cyclists.

Hofmann reported no ill effects and believed that—in small, controlled doses—LSD might hold value in psychiatry and neurology, a stance he maintained for the rest of his life. He continued to use LSD himself until about the time he turned 100, praising it as a meditation aid.

In 1968 Switzerland became the first country to partially ban the recreational use of LSD. The bike ride, though, proved harder to regulate.

Famous Birthdays

1832: Lucretia Garfield—American first lady

1903: Eliot Ness—American lawman who opposed Al Capone’s crime network

1968: Mswati III—King of Eswatini since 1986

1986: Candace Parker—American WNBA star