"Harry Potter" main cast Daniel Radcliffe shared that he often "blacked out" due to his alcohol problem.

In August 2010, news about Radcliffe's drinking problem surfaced. The 19-year-old actor then admitted that he often drinks until he can no longer remember anything. He said that he became very concerned of his public behavior when he was drunk and he became a recluse when he turned 20.

Looking back, Radcliffe's drinking problem started after he turned 18 and was allowed to drink. He said that he often drinks at his apartment alone. "I was living in constant fear of who I'd meet, what I might have said to them, what I might have done with them, so I'd stay in my apartment for days and drink alone," the young actor said.

His friends and co-workers started to notice his drinking problem. Daniel decided to talk with Gary Oldman who played the role of his godfather Sirius Black in the Harry Potter films. Gary Oldman battled his own alcoholism in the 1990s and Daniel thought that he could give him useful advice.

"You can't keep doing this. You've got too much to lose". And that really went in. But not even he could have stopped me alone - I had to stop myself. And stopping has shown me a world of happiness that I didn't think was possible," Oldman said to Radcliffe.

Daniel said that he stopped drinking last year after he became so reliant on alcohol to enjoy stuff. There were reports that Daniel was alcohol dependent when he was finishing the "Harry Potter" films.

Daniel Radcliffe is currently one of the most successful actors under 25 years old along with his "Harry Potter" co-stars.