The Harry Brown actor said he was never a fan of drugs, and the only time he ever smoked cannabis it had a devastating effect on him.
He said: Marijuana seemed like the most innocent of drugs, but I read it affects your memory.
I thought, I can't do it because I'll forget my lines. Then one day I did smoke a marijuana cigarette and I started to laugh and I laughed for five hours.
I nearly got a hernia, so I thought, s*d that and never got started on drugs.
The veteran actor, 76, said he was much happier drinking beer.
He added: I drank a lot of alcohol - that was my drug. I was never an alcoholic, but I could get drunk every now and again. You can get bombed on English beer very easily.
Michael also defended the actions of peers in the 60s when his hometown of London was awash with casual sex and drugs - saying it was natural to a generation growing up in the wake of World War II.
He added: It was amazing. It was a time when the British working class said, We're going to enjoy ourselves. You have to remember, we'd just had a war.
Harry Brown is released in UK cinemas on November 11.
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