John Altman took heroin "by accident".
The 'EastEnders' actor has opened up about his experiences of taking drugs, admitting he's tried everything from marijuana to LSD, but insists he only ever took the Class A drug because he mistook it for cocaine.
He shared: "I met people while travelling who were buying heroin and fixing up. But I've always hated needles, which probably did me a favour because I always avoided heroin.
"The only time I took it was at a party by accident, because I thought it was cocaine. I saw a white line on the table, I snorted it and then it made me sick."
Despite confessing he's sunk as low as his character, Nasty Nick Cotton, at times he claims they were some of his most enjoyable years.
He continued: "That was during my mad punk years, when we'd be up all night on the best cocaine in the world.
"There were a lot of walks home at dawn the next day. But for me they were great times."
The 62-year-old actor is now calling for drugs to be legalised, as he believes alcohol is more dangerous than any of the drugs he's taken.
He told The Sun newspaper: "My attitude to drugs now is most should be legalised. In the 21st century you should be able to buy recreational drugs from a Government-controlled vending machine.
"You wouldn't have so many people dying after using bad drugs.
"I have taken most drugs. But the worst one - the one that nearly destroyed me - was alcohol."
John - whose ex-wife Bridget Pouhan and daughter Rosanna left him at the height of his alcoholism - admits he drew on his experiences of taking illicit substances when playing Nick.
He explained: "Once you sober up, you see what alcohol can do to people. I spoke to an alcoholic once who had been in prison because he killed someone in a blackout, and he didn't even remember what happened.
"If I had carried on drinking, that could have been me. I could have been in prison, or dead.
"So I used that, and my experiences with drugs, as research when Nick was addicted to heroin. The memories came flooding back."
John is now preparing to say goodbye to his most memorable role as Nick is set to be killed off next week in the run up to EastEnders' 30th anniversary later this month.
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