Embattled Olympian Grant Hackett has been admitted to hospital with a severe mouth infection only days after groping a male passenger on a flight from Adelaide to Melbourne.

Hackett admitted himself to Pindara Private Hospital on the Gold Coast yesterday afternoon with uvulitis, a severe swelling of the uvula tissue that hangs from the back of the throat.

Swimming Australia head coach Jacco Verhaeren yesterday said he was shocked to hear of Hackett's illness but said it gave context to allegations the swimmer had lost his temper on a flight en route to the Gold Coast on the weekend.

"I don't know if the two things are related but he hasn't had a great week so far, so I really hope that he gets well," he said.


"He was, of course, disappointed not to make the Rio team but I thought he managed ... that very well with being a great commentator afterwards on TV.

"We were surprised and shocked about what happened ... and this on top of it again."

The 35-year-old athlete has suffered from the condition since before the Rio Olympic trials in Adelaide last week when he narrowly missed securing a position on the 4x200m freestyle relay squad.

It is believed the illness has gradually become worse, leading the swimming legend to admit himself to Pindara yesterday afternoon.

Hackett grabbed the nipple of Sydney real estate agent Martin Slobodnik on the plane flight from Adelaide to Melbourne on Sunday, with claims the athlete was heavily intoxicated.

Robina general practitioner Roger Halliwell said uvulitis could be a very painful condition and that if Hackett had been admitted to hospital, it was likely he had not performed his best during the Rio trials.

"What you end up with is like a cherry-red looking, angry, swollen uvula hanging down the back of the throat.

"I've seen people with that over the years and they're absolutely miserable.

"If he's been admitted to hospital with it and assuming that it's a true medical admission ... he's probably going to end up on ... antibiotics and reasonably solid pain killers and plenty of fluids.

"You would expect it to get better but that would be a very unpleasant condition to have.

"If he was coming down with this last week which is likely, his performance would have been off but he would have felt terrible."

Mr Verhaeren said Swimming Australia had offered Hackett support since the incident that led him to be questioned by the Australian Federal Police on Sunday.

"We're definitely going to give him any support he needs," he said.

"We had a bit of contact via text messages.

"Obviously finding out first if he was OK, if he was well and just reaching out to give him support if required."