D-lysergic acid diethylamide (LSD) is a hallucinogenic drug taken orally. It comes in many formes, but most commonly in "blotters," pieces of paper soaked in an LSD solution and then dried. It is also taken in pill form, gelatin sheets, liquid, and a powder. LSD is taken in doses of 50-150 micrograms, but it is almost impossible to determine the true dosage except by word of mouth.

LSD has been illegal in the United States since 1967. It was first made into a drug in 1943, and became popular in '60's.

LSD is not physically addictive, but if the user experiences good effects it can be mentally addictive.