Ian Thorpe's father says the Olympic legend is having a tough time battling depression, but he hopes his treatment will soon see him right.
The five-time Olympic gold medallist is in rehab after being found disoriented near his parents' Sydney home in the early hours of Monday, having taken a combination of antidepressants and medication for a shoulder injury.
Thorpe was sent for medical assessment to Bankstown Hospital, which wouldn't release him unless he agreed to enter a rehabilitation program.
"He is battling with his health issues at the moment and he is having a tough time," Ken Thorpe told News Corp on Tuesday.
"But hopefully in six months' time he will be out the other side."
America's Cup winning skipper John Bertrand has sympathised with Thorpe, saying he too battled depression after retiring.
"He is going through a very, very tough time," the told reporters in Melbourne.
"He has a very serious illness and we will endeavour to give all the support we can, through his friends, through his peers."
Mr Bertrand said retired athletes often faced difficulty finding a new challenge.
"It is one of those things. When I retired, I went through something similar after winning the America's Cup, nothing as extreme as what we are seeing with Ian," he said.
"That is the big challenge for any person coming from the highest of the high: to find a new area of endeavour within their life where they can become passionately involved and loving what they are doing.
"Ian is endeavouring to find that."
Mr Bertrand said while Thorpe's depression battle was a private matter, he would appreciate the support of his many fans.
Thorpe's manager James Erskine told AAP the swimmer's rehab is for depression.
Police were called to a house in Panania in Sydney's south on Monday after a resident reportedly spotted a man trying to break into a van.
But Mr Erskine said the 31-year-old had thought he was sitting in his friend's car.
He said Thorpe had been taking antidepressants and medication for his shoulder.
"He hadn't had a drink. He had zero alcohol in him," Mr Erskine said.
- Readers seeking support and information about depression can contact Lifeline on 13 11 14 or beyondblue on 1300 22 46 36.