In the world of celebrity rehab, Philip Seymour Hoffman's self-imposed stay at a detox center this month falls into the hard-core category: He tells TMZ he had been snorting heroin. The Oscar winner says he had kicked a substance abuse problem for more than two decades but lapsed about a year ago with prescription drugs. That gradually escalated to heroin, which he says he'd been using for about a week when friends and family got him to seek help. He's out after a 10-day stay. Hoffman will be in the new Hunger Games movie out later this year, notes Celebuzz.