29-year-old Monteith who plays Finn, a naïve high school football star in "Glee", told Parade magazine that he was nothing like his own screen character when he was 13 years old.
The actor revealed that he skipped school to get drunk, smoke pot and had attended over 12 different schools.
"I burned a lot of bridges. I was out of control, I had a serious problem (with drugs)," Monteith was quoted as saying.
Afraid that he could die, his mother and a group of friends staged an intervention.
"That's when I first went to rehab. I did the stint but then went back to doing exactly what I left off doing."
Monteith said he felt lucky to be alive after his troubled youth, and it was only later during his teen years that he felt it was time to get clean.
Since starring in "Glee", Monteith has starred in "Monte Carlo" with Selena Gomez and Leighton Meester.
Monteith will next appear in "Glee The 3D Concert Movie" a concert film based on the series' cast concert tour, which is expected to hit Malaysian cinemas on 18 August 2011 and in Singapore on 1 September 2011.