Irish actor Colin Farrell was terrified the first time he made love completely sober, because he was so used to having seedy sex in an alcohol and drug-induced haze.

The Phone Booth star, 37, overcame his addiction issues after a stint in rehab in 2005, and he admits it took him a while to fully adjust to a clean-living lifestyle.

He tells Elle magazine, "I made love to a woman about two-and-a-half years after I got clean, and it was one of the most terrifying moments of my life.

"It was in the afternoon. The windows and the curtains were open. It was lovely, and to be crass, it wasn't f**king. She was very gentle. But it was terrifying. Because I was just used to drunkenness and dark rooms and clubs and toilets and wherever."

But Farrell claims his performance in the bedroom wasn't his only worry: "I worried I wouldn't be able to talk, full stop (period). I hadn't uttered a word sober in about 15 years."