Katy Perry has admitting to taking pills before going on stage to calm her nerves.

The singer is one of the world's most popular live performers, but it seems the US star still suffers from stage fright.

She told Cosmopolitan that the medication - coupled with the desire to ensure her fans aren't left short-changed - helps encourage her to hit the stage.

Perry said: "I have to take beta blockers, I get so nervous. I think I have to get through this; I can't let these people down, but mostly I can't let myself down. I've been given a great opportunity and there are 500 bitches behind me who will snatch my weave off my head if I don't kick-ball-change through this two-hour show."

The singer meanwhile revealed that she also has a glass of alcohol waiting for her backstage after her show.

She said: "I always have one [a drink] waiting for me when I get off stage - a glass of champagne."

Watch Katy Perry perform live below: