Megadeth bassist David Ellefson last week recalled the moment he hit rock-bottom as a heroin addict.
David Ellefson in drug warning
Bassist recalls hitting rock bottom on heroin in just-say-no speech
And he warned that addiction in any form takes away the best of an individual.
Speaking to students at an Arizona high school, Ellefson said: "I was 15 when I started drinking. I started smoking pot when I was 16 and just followed that with cocaine and heroin.
"Heroin is an insidious and sneaky drug, and I was completely strung out on it."
The thrash icon finally reached the pits of despair during his third visit to rehab. He said: "When I finally hit that bottom, I said, 'Lord, please help me.' I woke up the next day and I didn't do drugs and I didn't drink. I didn't on day two, or day three.
"Now I'm 24 years sober – but it's one day at a time."
Ellefson described addiction as a lie, saying: "It like to get you alone, because when you're along it will talk to you and try to take you back to it.
"While it can make you feel unique, addiction takes away our uniqueness. We're like any other junkie – the best part of us goes away."
And he warned: "I have a lot of friends in the business who are just like I am. You don't know if you're going to take a drink, then get in the car to drive home and kill somebody, or kill yourself, but it happens.
"You don't know if smoking pot one time isn't going to lead to more. But I can tell you this: the best way to be absolutely sure is to just not start. Just don't start."
Megadeth are gearing up to appear on Motorhead's Motorboat cruising festival.