LSD — or, as the Second Doctor called it, lysergic acid diethylamide — was an hallucinogenic drug central to the American counterculture movement of the late 1960s.
A toxic strain of LSD, Blue Moonbeams, emerged in San Francisco during the so-called Summer of Love in 1967. It killed many of the city's young people. The Doctor synthesised what he felt was a less dangerous version of LSD and injected Jessica Willamy with it to help solve the mystery of the Colour-Beasts. (PROSE: Wonderland)
In 1968 the Seventh Doctor consumed three lumps of LSD-spiked sugar lumps in order to achieve an altered state of consciousness to achieve an altered state. (PROSE: The Left-Handed Hummingbird)
LSD was one of the drugs sold by Baz Bailey at Coal Hill School in the 1990s. (PROSE: The Eight Doctors)
While in San Francisco in 2002 Sam Jones suggested taking 'Berkeley’s most famous product' – LSD, to which Eighth Doctor recounted last dropping acid in 1968. (PROSE: Unnatural History)
Jason Kane did acid. (PROSE: Eternity Weeps)