Leo Varadkar has said he believes all politicians should be entitled to a "private life and a private past".
The Taoiseach appeared on the Hard Shoulder this evening to face questions from Ivan Yates, as part of a series of leaders' interviews ahead of next month's general election.
Mr. Varadkar was questioned by Ivan on his past drug use.
The Fine Gael leader claimed he's not the only Taoiseach to have ever taken drugs in the past, but said he didn't want to get into the details of his own past use because of the position of influence he holds.
He suggested a question about past drug use 'caught him off guard' during a Virgin Media TV debate yesterday.
However, Mr. Varadkar reiterated that he had only used cannabis in the past.
He said, "Obviously it was all when I was a student and in college.
"I don't want to send out the message to young people who are under pressure to experiment with drugs or try drugs that it's kinda OK... or that it's in any way cool, because it's not."
Mr Varadkar insisted he believes he's been "fully frank" with his answers, and that since being elected to public office in 2004 he has never used any illegal drugs.
During a radio interview, Mr. Varadkar suggested: "I'm a great believer that politicians should be able to have a private life and should be able to have a private past as well."
When questioned whether he's afraid any claims about private drug use could come to light, he responded: "I've spent the last three years with two gardaí with me at all times - so I think that probably answers that question."
He also observed: "I don't condone in any way young people or anybody experiment because of the potential health consequences of that.
"We've seen a number of very serious crimes in the last couple of weeks, and the truth is that is fuelled by people consuming illegal drugs."
Elsewhere, the Taoiseach said his party does not support the decriminalisation of drug use - citing Oireachtas research that has been done on the subject.
He explained: "What that group came up was the view that our legal system and the way it works is very different to the Portuguese system of codified law, where they have misdemeanours and so on.
"[The Oireachtas group] recommended that we shouldn't decriminalise it, but we should change the approach - which is to a health-led approach.
"That's actually government policy - it's not news. It was actually announced a month ago that we would move towards a health-led approach."