Highly potent hallucinogenic drug. An organic compound, LSD can be derived from the alkaloids ergotamine and ergonovine, found in the ergot fungus, but most LSD is produced synthetically. It can block the action of the neurotransmitter serotonin and produces marked deviations from normal perceptions and behaviour lasting 8–10 hours or longer. Mood shifts, time and space distortions, and impulsive behaviour may progress to paranoia and aggression. Flashbacks to LSD-induced hallucinations can occur years later. LSD is not an approved drug, and no clinically valuable uses have been found for it.

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