Eminem thinks his Obsessive Compulsive Disorder (OCD) is getting worse.

The 41-year-old rapper, who was addicted to prescription pills, said he only realised his compulsive habits were a problem after he quit drugs in 2008.

He told Rolling Stone magazine: ''I think my OCD is getting worse. It's self-diagnosed. Once I got sober I started noticing s**t about myself.

''Like running on the treadmill. If I had it in my mind that I needed to burn 500 calories, I hit that exact number.

''And with my music, I can tweak it forever to get it right, making changes no one else would even notice.

''But I don't know if it was always there and it was just repressed with drugs.''

The 'Berzerk' rapper previously admitted to obsessing when in the studio which is said to have delayed the release of previous albums.

Eminem has opened up about his addiction to drugs, admitting the pills he once popped almost killed him but the experience inspired his albums 'Relapse' and 'Recovery'.

The star also struggled with performing sober following his stint in rehab and said: ''I relapsed on drugs. It was a little creepy. I certainly had some dark times with that s**t, mostly due to taking a lot of pills and f****ing drooling on myself. It was a s***** time.

''I know I probably shaved a few years off my life.''