Openly-gay actor Neil Patrick Harris is struggling to deal with his insecurities as he prepares to star as a transgender glam rock singer in Broadway musical Hedwig and the Angry Inch, because he has never been comfortable in drag.

The Smurfs star will be slipping into heels and covering his face with make-up for the cult show revival, but he admits his physical transformation into the title character hasn't been as easy as he first thought.

He tells Out magazine, "Hedwig is bringing up a lot of super insecure things within me. I have never thought drag was intoxicating, I've never had a fun drunken Halloween in drag, never been in heels, really.

"I've lived my whole life being attracted by masculinity - it's why I like guys. I'm not a super effete person, and I have to turn into that, and in doing so it brings up a lot of homophobic insecurities within myself."