Scarlett Johansson sweats on the red carpet.

The 'Iron Man 2' actress admits nerves often get the better of her, no matter how much she is looking forward to making an appearance at a formal event.

She said: "I like the getting ready part. I like the hair and the make-up and the pretty dress. It's just getting on the red carpet I just instantly flop sweat.

"It's a weird chemical reaction I have somehow to the red carpet. I don't know what it is. Maybe it's just the carpet itself."

The 25-year-old star - who is married to actor Ryan Reynolds - admits she suffers a similar reaction when singing live and is even considering taking drastic action to curb her excessive perspiration.

She added to US TV talk show host Ellen DeGeneres: "I flop sweat then too. I probably need a shot to stop that."

Flop sweat is nervous perspiration caused by a fear of failure before an audience.

Scarlett is not the only star to confess to a problem with sweating.

Meryl Streep recently admitted she hates spending time in the kitchen because it makes her "sweaty and snappy".

She said: "I am a terrible cook. I can cook, but I fear that, as with video gaming or hardcore rap, I have no natural affinity.

"May I add that I am at perhaps my least glamorous when I am cooking, especially for other people? I am usually in a flop sweat, snapping at anyone in my line of sight."