Rapper Eminem is celebrating 12 years of sobriety with a promise to grow stronger in his fight against addiction, and says he is not afraid about the road ahead.

The rapper took to social media on Monday to show off a chip he received after staying sober for 12 years after past battles with addiction. He posted a shot of a black coin with the inscription, "One day at a time ... Unity Service Recovery".

"Clean dozen, in the books! I'm not afraid," the 47-year-old star wrote as a caption.

The Grammy-winning rapper's real name is Marshall Mathers. He has used his work to express his relationship with various drugs. He stopped consuming narcotics including Vicodin, Ambien and Valium in 2008, a year after he had a methadone overdose.

In a past interview with Vibe, Eminem opened up about how bad things were due to his addiction. He estimated that he consumed "anywhere between 10 to 20" Vicodin daily in addition to massive doses of Valium, Ambien and other substances.

"The numbers got so high. I don't even know what I was taking," he said.

Talking about overdose, he said that an "acquaintance" gave him medication he later learned was methadone, "which is used to wean heroin addicts off dope".

The "Without me" artist admitted that his "doctor told (him that) the amount of methadone (he'd) taken was equivalent to shooting up four bags of heroin".

"Had I known it was methadone, I probably wouldn't have taken it," he told the magazine.

In 2010, he released the album "Recovery", which won the Grammy for Best Rap Album the following year. He has been very productive in recent years, with 2017's "Revival", 2018's "Kamikaze" and his most recent work "Music to Be Murdered By".