The AFL could take action on its "storm in a coffee cup", with the league prepared to ban caffeine if players are abusing the substance.

The World Anti-Doping Agency, the international peak body that combats drugs in sport, took caffeine off its banned list last year.

But AFL chief executive Andrew Demetriou told radio station 3AW that the league would consider action.

"If it becomes so extreme that either we as the governing body would intervene, or we would rely on the medicos to tell us to intervene," Demetriou said.

Collingwood coach Mick Malthouse weighed into the fortnight-long debate over the use of caffeine tablets among AFL players, saying he wanted the practice banned.

He also wondered aloud that a couple of players had allegedly said they had taken caffeine supplements for several years, even though it was only just declared a legal substance.

"I've got to ask this question, how long has it been banned for? or how long has it been back in vogue for?," he said.

"I think you should check back through your records - I'm pretty sure I've heard two players saying `look, I've been using it for four years'.

"Well, if it came off last year, let's give a bit of leeway and say it's been off for two years and let's give another bit of leeway and say the players have been taking it for three years.

"Well that, to me, is a banned substance that's taken - as I say, I may have misread it, I may have misheard it."

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