LSD (lysergic acid diethylamide), also commonly known as acid, is a psychedelic drug that gained popularity in the 1960s as part of the counterculture revolution. Originally created in 1938 by Albert Hofmann from lysergic acid, which is found in the ergot fungus, LSD was researched as a potential psychotherapeutic medication in the 1950s and 1960s until it was classified as a controlled substance in the 1970s and all research was discontinued. There has been renewed interest in the use of the drug as part of treatment for depression, anxiety, and addiction, and much research is currently being devoted to documenting its clinical effects. The effects of a good LSD “trip” commonly include feelings of euphoria, visual or auditory hallucinations, and a sense of connectedness to the universe; a bad trip can include feelings of anxiety, paranoia, irrational fears, and other distressing emotional states. It is currently illegal to possess or ingest LSD for recreational purposes.