Tylenol was introduced in 1955 by McNeil Laboratories as a brand name for a non-prescription analgesic and antipyretic medication containing acetaminophen, which is the active ingredient. The substance acetaminophen itself was first synthesized back in 1878, but Tylenol as a branded product was launched in the spring of 1955, initially marketed as "Children's Tylenol Elixir" as a prescription medication before becoming widely available over the counter.