I must have missed that one. Haven't been seeing much of House since American Idiot took its place on Tuesdays.
I don't remember which episode it was - I googled it and, on the show, the prescription was for IBS. House prescribed 1 cigarette 2 times per day, which, supposedly, in real life, does help IBD.
I've been hearing recently of research involving the medicinal use of nicotine, and don't doubt that that it could be beneficial in some cases. Many extremely harmful substances can be beneficial in small doses.
Really, the tobacco wasn't the point, I just don't understand why they'd want to present pot in such a threatening way while pointing out the potential benefits of tobacco...