While he never drank on set, he admitted his alcohol consumption left him "dead behind the eyes".
Radcliffe has acknowledged that he was so desperate to avoid becoming an alcoholic that he now refrains from touching any alcohol.
In his latest interview, Radcliffe admitted being drunk while on the Harry Potter film sets although he does not disclose which ones.
It was a problem," Radcliffe told Heat magazine this week in an interview to promote his latest film.
I don't want to go into details, but I drank a lot and it was daily – I mean nightly.
He is currently promoting his current film, "The Woman in Black", a neo-Gothic horror movie, which opens this week, is his first post-Potter film.
The eight Potter films grossed more than $7.7bn (£4.87 billion) worldwide at the box office and made stars of Radcliffe, Emma Watson and Rupert Grint. »