Usually people say it was lead poisoning or alcohol poisoning. They think alcohol poisoning because there was an up coming election, and they think a politician kept giving him beers to vote for him, until he dropped dead in the street on the way to the polls. Hil - freaking - arious!
Poe was a great writer.
I've read a ton of his stuff including the Telltale Heart, the Raven, Ligia, City By the Sea (or wtv it was called), and some of his short stories like Fall of the House of Usher.
Yeah, he drank a lot, and he was depressed, especially after his wife died, but he had a really shitty childhood, if you ever read his history.
His parents died or something like that and his adoptive father was really Bipolar.
Edgar moved around a lot and other stuff.
However, if you hear that E.A.Poe was a drug addict, you can rest easy in the knowledge that he was not.
After Poe died, his publisher started that rumor to stop people from buing his books due to a personal vendetta. (or something like that)