I play in diaglo's OD&D game, and he already spoke to that.
In the 3.5 game I co-DM, a marijuana like drug is not uncommon. Also, I played a desert-dwelling dwarf who was addicted to a drug called guia that was used be desert guides. It gave a large bonus to Intuit Direction (3.0), making them more in touch with their intuition but also making it difficult to concentrate or think logically. So there was a bonus to all Wisdom skills and a minus to Intelligence skills. He became addicted in game, and had heard that withdrawal was painful and often deadly, so he continued to use the drug. In fact, when he moved to another city he had to help establish the guia trade so he would have a supply. He died still addicted, so I never found out the consequences of withdrawal.