"I've been helping Eminem over the last 18 months and he's doing brilliantly," John says, reports the British Press Association.
Speaking to BBC Radio 5 in the U.K. on Saturday, Sir Elton, 62, who has freely spoken about his own past issues with substance abuse, said: "I'm there if people want my help. If people ask for help you tell them where to go but there's no point advising people if they don't want to do it."
In May, Eminem admitted he'd suffered from a devastating drug addiction that led to him downing as many as 20 Vicodin, Ambien and Valium in a day.
"The numbers got so high," he told Vibe magazine, "I don't even know what I was taking.
Following his first stint in rehab in 2005, the rapper, 37, said he nearly overdosed after an acquaintance gave him unidentified blue pills, which a doctor later told him were actually methadone.