Hanson was hospitalised overnight after she collapsed on Sunday and lingering problems arising from the incident have thrown her Beijing Olympic preparations into disarray.

Hanson's father Ian, who is also the media director for the Australian swim team, said his daughter was still too exhausted to resume training.

"I think it's going to take some time," he told reporters on Wednesday.

"If she's in the pool by next Monday that would be a bonus, but I don't think we're going to see her in the pool anytime soon."

Hanson won a silver medal in the 100 breaststroke at the 2004 Athens Olympics and was also awarded a gold for swimming a heat for the Australian team that won the 4x100 medley relay.

Later that year, Hanson was named as the outstanding female swimmer at the short-course world championships in Indianapolis after winning a record six titles.

The 29-year-old failed to make the Australian team for this year's world championships in Melbourne but is hoping to be back for next year's Olympics.