LSD was developed in 1938 by Arthur Stoll and Albert Hofmann, Swiss chemists hoping to create a headache cure. In 1943 Hofmann accidentally ingested some of the drug and discovered its hallucinogenic effect. In the 1960s and 70s it was used by millions of young people in America; its popularity waned as its reputation for bad trips and resulting accidents and suicides became known. In 1967, the federal government classified it as a Schedule I drug, i.e., having a high abuse potential and no accepted medical use, along with heroin and marijuana. In the early 1990s it again became popular, presumably because of its low cost. It is produced in clandestine laboratories.