In 1796, Coleridge wrote his poem "Kubla Khan" — along with the "Ancient Mariner", it is his best-known work. At about the same time, in the later 1790s, Coleridge became addicted to opium. At that time the drug was legal, and was widely used as a painkiller. Coleridge's addiction to opium marked the rest of his life. His health suffered, and he had trouble supporting his wife and children. He also had a hard time finishing the writing projects he started.