NSW Origin mentor Ricky Stuart became the first high-profile rugby league coach to condemn the use of caffeine, saying it didn't provide a "good look" for youngsters.

Stuart became the latest leading sporting identity to weigh into the issue after AFL and rugby players - including Wallabies skipper George Gregan - admitted using caffeine as a pre-game performance enhancer.

Gregan said many Wallabies took caffeine tablets such as No Doz before games with the blessing of sports physiologists from the AIS because they could improve performance by up to seven per cent.

But Stuart - who is preparing NSW for next Wednesday's Origin series opener against Queensland at Brisbane - dismissed the idea.

Stuart said he hadn't even discussed the concept at his NRL club, the Sydney Roosters.

"It hasn't been discussed. I haven't seen it at the Roosters," he said.

"I wouldn't encourage it. I don't think it is a good look for our younger generation coming through and wanting to play our game.

"Having our club doctor here (in the NSW Origin team) I know we don't use No Doz at the Roosters and it won't be something that I will be promoting here."

Caffeine was taken off the sporting banned list 18 months ago but the World Anti-Doping Agency has announced it will consider reinstating it.

Meanwhile, Friday night's NRL opponents - Parramatta and Manly - announced major re-signings.

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