Adelaide utility Scott Stevens has quit the AFL not knowing when he will recover from puzzling concussion symptoms.

The 29-year-old endured constant headaches, nausea and vomiting since being concussed in April in what he termed "fairly minor incidents" at training.

Stevens has not played since round three and spent much of the time since unable to read or watch television, let alone exercise.

The 144-gamer said he is not willing to risk his future health by returning to the AFL.

"Concussion is a brain injury and it's pretty serious and it effects my whole quality of life and has ramifications away from football," Stevens said on Tuesday.

"I'm not prepared to go through this again. It has a big impact on your whole life."

Scans and tests failed to diagnose the core of the utility's problems.

Stevens, a member of Adelaide's leadership group since 2009, had been assured by medicos he would fully recover - but he does not know when.

"I have been getting better slowly and I will continue to get better but when that is, I'm not sure," he said.

"I haven't lost any brain function or anything like that and I will fully recover.

"The symptoms include headaches, nausea, vomiting. I have had a lot of vision problems.

"They haven't gone away - it's not like I get them when I'm just at the club or exercising, they're 24/7."

Stevens said he had been concussed several times during a career which began in 2002 with the Sydney Swans.

"Every concussion is different. How one player reacts to it is different to how other players react to it," he said.

"I think all doctors in the AFL care for their players, and coaches do as well. Sometimes, players are right to go back on or play the next week. Unfortunately for me, I wasn't."

Stevens made a last ditch effort to return to training a couple of weeks ago.

"I just went backwards for a couple of days, the symptoms came back and probably increased," he said.

The setback confirmed the end of a playing career which included twice winning Adelaide's best team man award.

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