Former full-forward Warwick Capper briefly experimented with illegal drugs during his AFL career, his newly-released autobiography reveals.

Capper said he twice took tablets containing speed, including before Sydney's 1986 qualifying final against Carlton.

He would be sanctioned under the AFL's current anti-doping policy if he tested positive for speed.

Capper said he and an unnamed Swans team-mate tried the tablets, which the full-forward heard about while working at a transport company.

"We used to get these tablets ... speed tablets - a friend, who also played for the Swans, and I thought we'd try them before two games, including the 1986 qualifying final against Carlton at the MCG," Capper said in his book "Fool Forward".

Speaking on Thursday night on The Footy Show, Capper added: "It's actually no more than a ginseng tablet, I didn't know what it was at the time.

"It had a touch of speed, (which) I found out two days later, I actually only took two tablets....they were on `script (prescription) only, one of my friends just gave me a couple.

"It lasted about three hours, I felt a bit tired for a couple of days and that was about it.

"I don't recommend it, I was a bit silly doing it, I regret it now - it was one of those things."

He would not reveal the identity of the other Swans player.

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