VETERAN Brisbane Lions champion Jonathan Brown has announced his immediate retirement.

Brown, 32, said his decision was based on strong medical advice following his third heavy head knock in 12 months in the Lions' 45-point loss to Greater Western Sydney on June 14.

"It's a very difficult time, but at the same time I'm very happy on reflection," 32-year-old full forward Brown told reporters at the Gabba on Monday.

"Unfortunately though, the last week or so it's become evident after my concussion last week that I don't respond or bounce back like I used to from those hits.

"I had pretty strong medical advice this week that it was in my best interest to stop.

"It's been a hard pill to swallow, even though deep down inside I knew that was the right answer."

Brown, a three-time premiership winner over 256 games, said his 15th season in the AFL was likely to have been his last anyway.

"It wasn't worth the risk of going out there and copping another head knock and jeopardising my future with my wife and kids," he added.

"I've got to keep pretty sharp for the young fella, to chase him around."

The two-time All-Australian said he would stay involved with the club off the field for the remainder of the season.

"I'm not going to dramatise it - I'm OK, I'm going to recover. I'm sure my symptoms will clear up soon," Brown said.

He thanked coach and former teammate Justin Leppitsch for his support, insisting he hadn't pressured him into retiring.

"I'm looking forward to the future, whatever that may be."

The club legend said he believed the 17th-placed Lions were heading in the right direction, despite Saturday's 83-point mauling by Fremantle.