LSD-25 was the twenty-fifth compound developed during Albert Hofmann's study of amides of Lysergic acid, hence the name. LSD is considered a semi-synthetic chemical, the natural component of LSD-25 is lysergic acid, a type of ergot alkaloid that is naturally made by the ergot fungus, a synthesizing process is necessary to create the drug.
LSD was being developed by Sandoz Laboratories as a possible circulatory and respiratory stimulant. Other ergot alkaloids had been studied for medicinal purposes, for example, one ergot was used to induce childbirth.