Hilary Swank needed stitches after filming 'P.S. I Love You'.

The Oscar-winning actress admits it is ironic how she had a lot of physical challenges when she played a female boxer in 'Million Dollar Baby' and walked away unscathed, but had to shut down production on the romantic comedy for a week after co-star Gerard Butler accidentally flung a pair of braces at her forehead.

She explained: "There was a perfect brace mark in my forehead. I was laughing but crying at the same time. Everyone was standing around the bed and I went to touch my head and my make-up artist went, 'No, no, no, don't touch it!'. So I knew it was bad.

"I had to have stitches and we shut down production for a week. It's crazy to think I did a whole boxing movie and my face went virtually unscathed and then I do a romantic comedy and I get stitches in my head!"

The 36-year-old star revealed her part in 'P.S. I Love You' came about after screenwriter and director Richard LaGravenese wanted to show her "funny side" after first casting the actress in 2007's 'Freedom Writers'.

Hilary added to Total Film magazine. : "While we were doing 'Freedom Writers', Richard LaGravenese said, 'God, you're so girlie, you're funny, I want to show this side of you'. I loved working with him on 'Freedom Writers' so it was great to work with him back-to-back on 'P.S. I Love You'."