From a 1997 interview:
D&C: I wanted to ask you about drugs: It's not something that I've read you talk about.
Bono: Just say Noel. [laughing]
D&C: If you want the good gear just say Noel. [laughter] Did you ever go through a period
Bono: It's not my thing. I'm not really into it, but I feel for people who are. I tried to bring up the debate and talk about the facts and it got distorted on me and I was tabloided into 'I think drugs are great' and I don't, actually. I think drugs are lazy, but I don't knock that. Drink is lazy, cigarettes are lazy. That's the thing. The thing about drugs and me is that, as a person, the sort of drugs I need are probably the sort of drugs to turn me down, not up
I'm thinking he brought up the general topic at some point and then, like he said, it turned into a 'Bono admits to loving drugs!' headline. What his original comments were I'm not sure.