A combination of antidepressants and painkillers is being blamed for Ian Thorpe's latest problems after the five-time Olympic gold medallist was admitted to a rehabilitation clinic to receive treatment for depression.

Thorpe's manager James Erskine told the ABC the swimmer was found disoriented early Monday morning in the Sydney street where his parents live.

Mr Erskine said Thorpe had taken painkillers for a shoulder operation he had last week and also had antidepressants in his system.

"He'd been taking prescribed drugs, painkillers for his shoulder and he's also on prescription drugs for anti-depression... but it's obviously a mixture of it and that mixture made him disorientated because he was wandering around at 3 o'clock in the morning," he said.

Mr Erskine says residents rang police after Thorpe tried to get into a car that he thought belonged to a friend.

Sorry, this video has expired 'Athlete identity': How hard is it to let go of sporting glory?

"He became disorientated and he tried to get into what he thought was a friend's car, but it wasn't his friend's car at all," Mr Erskine said.

"It looked the same and I think it was the same make, same colour, and obviously somebody saw it or the owner of the car saw it [and] called the police.

"The police came; they were fantastic, they realised it was Ian Thorpe and they called an ambulance."

Mr Erskine says Thorpe was taken to Bankstown Hospital.

"There was no alcohol involved, he hadn't been drinking or anything like that," Mr Erskine said.

"The hospital then suggested - or more than suggested, I think - that he should go into rehab for depression and that's what's happened."

The champion swimmer released an autobiography last year in which he said he had struggled with alcohol abuse and depression.

Manager rubbishes reports Thorpe was in rehab for alcohol abuse

Sorry, this video has expired This is Thorpe's first rehab admission: Manager

Mr Erskine rubbished reports that Thorpe was in rehab for alcohol abuse last week.

"The reports are completely wrong," he said.

"The News Limited journalist who did that made it up.

"This is the first time he's been to rehab, so at the end of the day it was just bollocks.

"He fell and suffered a shoulder injury, went to hospital, had an operation, came back to his parents' house and was recuperating.

"That's what's happened.

"He has at times in the past had too much to drink. Most of us have I suppose, but on this occasion and on this incident, there was no alcohol involved."

Thorpe had been living in Switzerland for 18 months but returned to Sydney to spend the Christmas period with his family at his parents' Panania home.

Mr Erskine said he had spoken with the Olympian's mother, "who's obviously, like any mum would be, with big concerns".

"I don't know enough about depression to know, but he's been in my office after Christmas; he was fine," Mr Erskine said.

"I think these sort of... depression hits you and Jeff Kennett's talked about it a lot and suddenly you get it and you get into a state and that's it.

"But, no, judging from what everyone said today and all the sort of well-wishing, I mean, I don't think there'd be a person in Australia who witnessed Ian's successes in the pool that doesn't wish him the best of luck."