The 25-year-old pop superstar is very open about having abused drugs while trying to find herself as a struggling musician playing in New York clubs.
'I just was partying and being very self-indulgent and trying to find myself,' she told fashion icon Jean Paul Gaultier in a TV interview.
'And in hindsight it's so dangerous - I really don't encourage anyone to follow that path,' she said.
But it was the embarrassment of her family finding out in a very dramatic way that made her quit drugs on the spot.
'I actually was doing drugs in my parents' house one day and they didn't know I was in the bathroom,' she recalled.
'And I came out and my father could tell. And I just remember feeling so embarrassed and I quit instantly.
'I care so much what my father thinks. I'm very old-fashioned Italian in that way. It was pretty instant.'
She insists she does not miss her drug years.
'Over the years I've realised that the joy and euphoria I experience in the relationship with my fans is so much greater than any drug could be,' she insisted.