Joyce 'walking ad' for wearing a hat

Acting Prime Minister Barnaby Joyce, sporting large red marks around his right eye and on his forehead, describes himself as a "walking advertisement for why you should wear a hat".

Mr Joyce took to social media after speaking to reporters in Brisbane on Monday to explain how he's paying the price of previous years being under the sun without the broad-rimmed hat he regularly wears these days.

"Cancers on my face are being burned off with a cream so I'm going to look like this for a few weeks," he wrote on Instagram.

"It doesn't add to my complexion, but some say it doesn't take away from it either.

"So if you're in the sun, cover up, or you'll be looking the same in a few years' time - and you just don't know what you'll have to front up to."