Saints' McCartin still out with head knock

St Kilda say there's no time-frame for the return of Paddy McCartin, who is still experiencing concussion symptoms three weeks after his most recent head knock.

Paddy McCartin's AFL career with St Kilda has been curtailed by a number of head knocks. (AAP)

St Kilda's Paddy McCartin is still suffering concussion symptoms three weeks after a head knock, leaving the forward sidelined indefinitely.

The former No.1 draftee suffered his eighth concussion since 2014 in St Kilda's pre-season game earlier this month.

The 22-year-old is unable to train, although he is a regular visitor at the AFL club to meet with medical staff and his teammates.

"It's been three weeks now since the incident and Paddy still has some symptoms and that's going to take a while," coach Alan Richardson said on Friday.

"We can't really put a time frame on when it is that he'll be back training flat-out or even playing."

Richardson said the current recovery period was tracking similarly to his most previous concussion.

The coach said McCartin and the club hadn't discussed his playing future or the possibility of retirement.

"We're not in that space of having conversations long term, it's about 'let's just get him right' and then deal with those issues down the track," Richardson said.