Opium

Opium was an extract from opium poppies. Its was also known as papaver somniferum, which translated to "pipe of poppy".

Opium was commonly smoked as a drug. Li H'sen Chang smoked opium to dull the pain of his injuries. Leela believed it to smell like decaying fruit. (DW: The Talons of Weng-Chiang)

Thomas De Quincey recorded the effect of the drug, notably hallucinations, in his book Confessions of an English Opium-Eater. (EDA: The Banquo Legacy)