The 'Poker Face' singer began using illegal substances after she dropped out of a music course at New York University in 2005, and she insists getting high helped her creativity.
The 24-year-old pop star said: "[Using drugs] I really figured out the art I wanted to make and was inspired. Some people find inspiration in dark places. I guess I'm one of them.
"What always made me different is that if I was doing drugs I was also making music. I wasn't just doing drugs."
The eccentric singer - real name Stefani Germanotta - also revealed her mother Cynthia didn't understand why she felt she needed to take drugs and was confused by her early performances.
She told Q magazine: "At the beginning I was doing performance art in handmade leather and leopard bikinis talking about oral sex and Andy Warhol and heavy metal. My mom was like, 'You've lost your mind.' I was doing drugs, I was really out of control. But I never got so far into it that I overdosed or anything."
However, Gaga is adamant she doesn't need drugs anymore and has toned down her wild lifestyle.
She explained: "Once you open those doors they're open for ever. People who say they need [drugs] to be creative are full of s**t. I'm not some chick on the road getting high and f***ed up every night. I wake up, drink coffee and get on the phone to talk about the creative direction of the next video."
The singer caused a furore recently when she admitted in a magazine interview she occasionally took cocaine.
She said: "I won't lie; it's occasional. And when I say occasional, I mean maybe a couple of times a year."