Sir Elton John's growing status as a down-to-earth counsellor to celebrities was reinforced this weekend when the veteran singer and songwriter spoke for the first time about the help he is giving the American hip-hop star Eminem.

Talking to Danny Baker on his Radio 5 Live show yesterday, John said it is only possible to counsel addicted friends when they are ready. "I've been helping Eminem in the last 18 months and he is doing brilliantly," he said, going on to refer to his own successful struggle with addiction. "When you give it up, you tend to think everybody else has given it up, but of course it is just as prevalent as it ever was. And nowadays pills, such as downers, are even more damaging."

Eminem has an acknowledged problem with prescription drugs and was treated for a near-fatal methadone overdose. The artist became friends with John after a rocky start. When they met at the Grammy Awards in 2001 John, who has had a civil partnership with David Furnish since 2005, was critical of Eminem's comments about homosexuality. But the friendship became important to Eminem in the run-up to the release of last year's album Relapse.

"[Elton] had a substance-abuse problem in the past. So when I first wanted to get sober, I called him, because he's somebody in the business who can relate to the lifestyle and how hectic things can be," Eminem told a Detroit newspaper last year. "He understands, like, the pressure and any other reasons that you wanna come up with for doing drugs."

Baker asked the musical knight, now 62, if he ever felt like shaking other friends who were unable to kick their drug and alcohol habits. "I'm there if people want my help," he said. "If people ask for help you can tell them where they should go, but there is no point advising someone if they don't want to do it."

The singer discussed his offers of help to the troubled performer George Michael, who is reported to have dismissed his approaches.

"People used to tell me to clean my act up and I didn't want to know," he said. "And I know that George has been very vocal in the papers saying that Elton should shut his mouth and how he is sure I would love him to come and bang on my door and ask for help."

John said that Michael was right to suggest it was "none of my business", but drew a comparison with his own behaviour before he recovered from 16 years of addictive behaviour: "I didn't want anybody's help. I used to get very annoyed. In fact, I didn't speak to some close friends for a year because they dared to tell me I was being an idiot."

Lyricist Bernie Taupin, John's songwriting partner, wrote Someone Saved My Life Tonight after he prevented his friend from committing suicide. Those "lost years", the star told Baker, are still the subject of great regret. "Initially, it was fun, but I am not a man who can just do one of anything. I have got that kind of nature," he said. "So I could not do one gram of coke, I had to do six grams and then I would want more. It ended up being incredibly depressing."

The singer's reputation as a confidant is founded on the help he offered actor Robert Downey Jr and his failed attempts to intervene in the life of the former Libertines front man Pete Doherty. He also offered Victoria and David Beckham the use of his villa and yacht when their marriage was in difficulty.