LSD--Lysergic acid diethylamide, commonly called LSD, acid, or LSD-25, is a semisynthetic psychedelic drug. The short form LSD comes from the German "Lysergsäure-diethylamid". A typical single dose of LSD is between 100 and 500 micrograms, an amount roughly equal to one-tenth the mass of a grain of sand. Threshold effects can be felt with as little as 20 micrograms[1] but most users may prefer to take larger doses.[2]

The effects of LSD can vary greatly depending on factors such as previous experiences, state of mind and environment, as well as dose strength. Generally, LSD causes expansion and altered experience of senses, emotions, memories, time, and awareness for 8 to 14 hours. In addition, LSD may produce visual effects such as moving geometric patterns, "trails" behind moving objects, and brilliant colors. LSD does not produce hallucinations in the strict sense but instead illusions and vivid daydream-like fantasies, in which ordinary objects and experiences can take on entirely different appearances or meanings. At higher doses it can cause synesthesia. Some users cite the LSD experience as causing long-term or permanent changes in their personality and life perspective.

LSD is synthesized from lysergic acid derived from ergot, a grain fungus that typically grows on rye. LSD is sensitive to oxygen, ultraviolet light, and chlorine, especially in solution (though its potency may last years if the substance is stored away from light and moisture at low temperature). In pure form it is colorless, odorless, and mildly bitter. LSD is typically delivered orally, usually on a substrate such as absorbent blotter paper, a sugar cube, or gelatin. In its liquid form, it can be administered by intramuscular or intravenous injection, or even in the form of eye-drops.

Introduced by Sandoz Laboratories as a drug with various psychiatric uses, LSD quickly became a therapeutic agent that appeared to show great promise. However, the extra-medical use of the drug in Western society in the middle years of the twentieth century led to a political firestorm that resulted in the banning of the substance for medical as well as recreational and spiritual uses. Despite this, it is still considered a promising drug in some intellectual circles, and organizations such as MAPS, Heffter Research Institute and the Albert Hofmann Foundation exist to fund, encourage and coordinate research into its medical uses.