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Cory Monteith, who plays Finn Hudson on 'Glee,' started smoking pot and drinking alcohol as a teenager and entered rehab when he was 19, after using 'anything and everything' he could get his hands on, according to Parade magazine. He relapsed in 2013. On April 1 of that year, his rep confirmed to OTRC.com that he had entered a treatment facility to treat substance addiction, without elaborating.
(Pictured: Cory Monteith talks to OTRC.com about 'Glee's season 4 at VH1's Do Something! Awards on Aug, 19, 2012.)