Philip Seymour Hoffman Checked Into Detox For Narcotic Abuse

Philip Seymour Hoffman just got out of detox for a drug problem that was spinning out of control ... a problem he desperately wanted to nip in the bud ... and he's already back doing a movie.

Hoffman -- who struggled with substance abuse in the past but kicked the habit for 23 years -- fell off the wagon more than a year ago. He tells TMZ it started slowly with prescription pills, and recently escalated to snorting heroin.

Hoffman -- who won a Best Actor Oscar in 2006 for "Capote" -- tells us the heroin use only lasted a week or so and he quickly realized he needed help, so he checked himself into a detox facility on the East Coast.

He says he was at the facility for 10 days and checked out last Friday. Hoffman credits what he calls "a great group of friends and family" for helping him seek the treatment he needed to get better.

And at least for now, it seems it worked, because Hoffman is clean and back on a movie set in Europe.