The 30 year-old admitted himself into rehab voluntarily to deal with substance addiction. He has been known to have suffered from issues relating to addiction in the past.
"He graciously asks for your respect and privacy as he takes the necessary steps towards recovery," contactmusic.com quoted a source as saying. Back in 2011, Monteith spoke about past issues that he had had with substance abuse and revealed that he had been in rehab before, when was just 19.
In an interview in 2011, the 30-year-old explained that he hoped that being public and honest about his rehab would help other people going through similar struggles.
"I don't want kids to think it's okay to drop out of school and get high, and they'll be famous actors, too," he said. "But for those people who might give up. Get real about what you want and go after it," he added. The show's producers are fine with his decision.
"Monteith is a beloved member of the 'Glee' family and we fully support his decision to seek treatment. Everyone at the show wishes him well and looks forward to his return," said the show's producers, 20th Century Fox.