LSD, SAY is a four letter acronym for the DRUG Lysergic acid diethylamide, commonly known as LSD. It is a powerful hallucinogenic DRUG that was first synthesized in 1938 by Swiss chemist Albert Hofmann. LSD is known for its ability to produce profound changes in perception, mood, and thought. It has been used recreationally, in psychotherapy, and in religious contexts. The effects of LSD can last up to 12 hours and can include visual and auditory hallucinations, altered sense of time, and feelings of euphoria.