Lysergide (LSD) is a semi-synthetic hallucinogen, and is one of the most potent drugs known. Recreational use became popular between the 1960s to 1980s, but is now less common. It is generally believed that most LSD is produced outside Europe, but secondary preparation of dosage units by dipping or spotting paper squares is more widespread. These dosage units usually bear coloured designs featuring cartoon characters, geometric and abstract motifs. LSD is related to other substituted tryptamines, and is under international control.