Given that she's naked for a large chunk of her raunchy new film, Love and Other Drugs, it may come as a surprise that Anne Hathaway wasn't completely relaxed when it came to disrobing for her role as Maggie - an emotionally unavailable Parkinson's sufferer.

"I can tell you the most scariest part about doing nudity is two things," the 28-year-old told media while in Sydney today for the film's Australian premiere. "One is having to watch it with an audience, because it becomes a little surreal, and I must say not the most comfortable thing in the world. The second part about doing nudity is talking about it — that’s a little scary, and all the attention it gets."

Anne wore a Christopher Kane dress to the press conference.

However, she candidly admitted that it's far easier to shoot a sex scene with someone attractive, "to work with things that are naturally occurring." When that someone just happens to be her perfectly-chiselled co-star Jake Gyllenhaal, it's not hard to see why - and what might be occurring.

For Gyllenhaal, who plays a "gross, charismatic and wonderful" serial womaniser-turned-Viagra-rep who falls for Maggie, the role required "sacrifices". "My character in this movie has a lot of sex, so I had to practice a lot. You really have to devote yourself to a role," he quipped. And the difference between working with Hathaway on this Edward Zwick film and Brokeback Mountain, where he played her gay husband? "This time I got to be into her."

The pair will grace the red carpet tonight for the Sydney premiere; Love and Other Drugs will be in cinemas December 16.